Article

Starch gelatinization and its complexity for analysis

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The term “gelatinization” of starch generally describes an irreversible structural change observable on all product design scales ranging from micro to macro level. These structural transformations of starch during thermal impact and in following production steps are highly dependent on several different aspects, which are, however, not sufficiently specified. In order to achieve a better understanding of these heat-induced changes it is necessary to cluster the influencing aspects into the following two categories, raw material properties and process parameters. The development of physical analytical methods with their corresponding gelatinization aspects, in relation to their process parameters, is illustrated in this review. Based on the current knowledge it becomes apparent that no analytical system is present which would allow the investigation of starch gelatinization and the resulting structural changes on different length scales in food products. Therefore, the application of a specified non-invasive online analyzing system to follow the starch gelatinization within a complex food matrix is recommended.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Starch, a granular polysaccharide composed of monomers of α-d-glucose and obtained from plant sources such as corn and rice, contains two fractions: amylose (about 25%), an amorphous, linear polymer whose glucose units are connected by α(1→4) glycosidic bonds, and amylopectin (about 75%), a crystalline, branched polymer whose glucose units are connected by both α(1→4) and α(1→6) glycosidic bonds (Aliasson, 2004). The gelatinization of starch granules in water by heating, which allows them to absorb water and swell then eventually break their granular form, gives them a thickening and gelling ability widely used in fine-tuning the textures of food, but this process is irreversible (Goff & Guob, 2019;Schirmer et al., 2015;Thys et al., 2013). There is evidence to suggest that while gels made from amylose are firm and thermo-irreversible, amylopectin gels are soft and thermoreversible (Jeong et al., 2012;Sasaki & Yasui, 2000;Schirmer et al., 2015). ...
... The gelatinization of starch granules in water by heating, which allows them to absorb water and swell then eventually break their granular form, gives them a thickening and gelling ability widely used in fine-tuning the textures of food, but this process is irreversible (Goff & Guob, 2019;Schirmer et al., 2015;Thys et al., 2013). There is evidence to suggest that while gels made from amylose are firm and thermo-irreversible, amylopectin gels are soft and thermoreversible (Jeong et al., 2012;Sasaki & Yasui, 2000;Schirmer et al., 2015). It has been shown that amylopectin gels can be made slowly by storing a highly concentrated amylopectin solution (40% pyrolized waxy maize) at 4 • C for 21 days, and that this gel melts at about 45-60 • C (Durrani & Donald, 1995). ...
Article
While nature behaves like an irreversible network with respect to entropy and time, certain systems in nature exist that are, to some extent, reversible. The property of reversibility imparts unique benefits to systems that possess them, making them suitable for designing self‐healing, stimuli‐responsive, and smart materials that can be used in widely divergent fields. Reversible networks are currently being exploited for applications in tissue engineering, drug delivery, and soft robotics. They are also being utilized as low‐calorie fat mimetics with melt‐in‐your‐mouth textures, as well as being explored as potential scaffolds for three‐dimensional (3D) printable food, among other applications. This review aims to gather representative examples of heat‐ and shear‐reversible networks in the food science literature from the last 30 or so years, in other words, reversible food gels made either from linear biopolymers or from colloidal, particulate dispersions, including those that have been modified specifically to induce reversibility. An overview of the network mechanisms involved that impart reversibility, including a discussion of the strength and range of forces involved, will be highlighted. A model that explains why certain networks are thermoreversible while others are shear‐reversible, and why others are both, will also be proposed. A fundamental understanding of these mechanisms will prove invaluable when designing reversible networks in the future, making possible the precise control of their properties, thus fostering innovative applications within the food industry and beyond.
... Among all PPI pastes, PS showed higher viscosity than the three other pastes ( Figure 5). This indicates that starch increases the viscosity, which could be explained on the basis that cooked starch absorbs water and forms an intensive gel structure [48,49]. However, adding both starch and fat did not negatively influence the flow behaviour. ...
... forms an intensive gel structure [48,49]. However, adding both starch and fat did not negatively influence the flow behaviour. ...
Article
Full-text available
Meat analogue is a food product mainly made of plant proteins. It is considered to be a sustainable food and has gained a lot of interest in recent years. Hybrid meat is a next generation meat analogue prepared by the co-processing of both plant and animal protein ingredients at different ratios and is considered to be nutritionally superior to the currently available plant-only meat analogues. Three-dimensional (3D) printing technology is becoming increasingly popular in food processing. Three-dimensional food printing involves the modification of food structures, which leads to the creation of soft food. Currently, there is no available research on 3D printing of meat analogues. This study was carried out to create plant and animal protein-based formulations for 3D printing of hybrid meat analogues with soft textures. Pea protein isolate (PPI) and chicken mince were selected as the main plant protein and meat sources, respectively, for 3D printing tests. Then, rheology and forward extrusion tests were carried out on these selected samples to obtain a basic understanding of their potential printability. Afterwards, extrusion-based 3D printing was conducted to print a 3D chicken nugget shape. The addition of 20% chicken mince paste to PPI based paste achieved better printability and fibre structure.
... Starch's pasting behavior is a mixture of complex processes that occur after gelatinization, including starch granules transitioning from swelling to rupturing, amylose leaching and high-energy gel development [28,29]. Figure 3 presents the pasting properties of potato starch under different temperature regimes. ...
Article
Full-text available
Potato flour is an important raw material for potato staple food products; nevertheless, the quality and flavor vary significantly due to process changes. In this study, the physicochemical features of fresh and five different dehydration temperature potato samples, including the degree of starch gelatinization (DG), pasting, structure properties and volatile components, were compared to investigate the effect of hot air drying (HAD) on potato flour. The results showed that the degree of pasting, viscosity and volatile aroma components changed significantly with differences in drying temperature. With the increase in drying temperature, the gelatinization degree and peak viscosity of potato powder increased or decreased, the breakdown viscosity of HAD-50 was higher, the setback viscosity of HAD-90 was higher, while the crystallization zone of HAD-90 was destroyed due to the high temperature. The flavor components of potato flour are increased during processing due to lipid oxidation, Maillard reaction and thermal degradation. The level of aldehydes,3,5-Octadien-2-one and E,E)-3,5-Octadien-2-one gradually reduced as the processing temperature increased, while the content of furans grew and then decreased, nonanal and 2-Penty-l-Furan increased. Overall, lower HAD temperatures are beneficial for the quality and flavor of potato flour. The information presented here will be useful for the further development of potato flour products.
... Gomez and Aguilera (1984) also reported that the DG of extruded corn starch increased from 16% to 63% as the moisture content decreased from 32% to 14%. During the extrusion process, gelatinization accounts for the majority of the structural changes in starch granules with a specific starch-to-water ratio (Schirmer, Jekle, & Becker, 2015). In particular, higher temperature and lower moisture content has been shown to enhance the shearing force and induce the destruction of hydrogen bonds and crystal structures in the starch granules Sun et al., 2019). ...
Article
Tartary buckwheat is a promising pseudocereal with health benefits. However, native Tartary buckwheat flour (NTBF) cannot satisfy the specific physicochemical properties required for food processing due to its gluten-free character. This study investigated structural and physicochemical properties, the starch digestibility of Tartary buckwheat flour pregelatinized with traditional extrusion processing technology (TEPT), and improved extrusion processing technology (IEPT). TEPT had a higher destructive effect on the starch structure than IEPT. Amorphous flakes and incomplete starch granules were observed in pregelatinized Tartary buckwheat flour (PTBF). After extrusion, the relative crystallinity, endothermic enthalpy, the slowly digested starch (SDS) and resistant starch content decreased by 23.76–70.44%, 48.91–100.00%, 28.43–88.65% and 53.23–78.79%, respectively. However, the amylose molecular weight of branched starches, the degree of gelatinization (DG), the water absorption index (WAI), the starch digestibility, the rapidly digested starch content, and the glycemic index increased by 29.00–119.04%, 26.05–1279.88%, 4.2–188.70%, 9.2–19.96%, 113.04–236.25%, and 25.55–37.00%, respectively. For IEPT, crystallinity decreased with the increase in extrusion temperature and the decrease in feed moisture, whereas the DG and WAI showed a contrary trend. Compared to TEPT (5.05%), PTBF obtained with IEPT retained a higher SDS content (11.28–31.85%). Starch digestion of all samples possessed a combination of sequential and parallel digestion patterns. Correlation analysis suggested that an increase in the destructive effect on the starch structure from IEPT to TEPT was responsible for the changes in physicochemical properties and improvement of in vitro starch digestibility. This study provides a scientific basis for the quality improvement in Tartary buckwheat starchy foods following extrusion.
... Heating an aqueous starch suspension induces a number of structural changes in granules during gelatinization. Thermally induced structural changes depend on the amount of water in starch suspension [43][44][45]. Our investigation began by studying the simplest system, i.e., starch solution without any added hydrocolloids. Figure 1 shows thermograms of different starch weight fractions to water suspensions. ...
Article
Full-text available
Obtaining good-quality gluten-free products represents a technological challenge; thus, it is important to understand how and why the addition of hydrocolloids influences the properties of starch-based products. To obtain insight into the physicochemical changes imparted by hydrocolloids on gluten-free dough, we prepared several suspensions with different corn starch/potato starch/hydroxpropyl methyl cellulose/xanthan gum/water ratios. Properties of the prepared samples were determined by differential scanning calorimetry and rheometry. Samples with different corn/potato starch ratios exhibited different thermal properties. Xanthan gum and HPMC (hydroxypropyl methyl cellulose) exhibited a strong influence on the rheological properties of the mixtures since they increased the viscosity and elasticity. HPMC and xanthan gum increased the temperature of starch gelatinization, as well as they increased the viscoelasticity of the starch model system. Although the two hydrocolloids affected the properties of starch mixtures in the same direction, the magnitude of their effects was different. Our results indicate that water availability, which plays a crucial role in the starch gelatinization process, could be modified by adding hydrocolloids such as, hydroxypropyl methyl cellulose and xanthan gum. By adding comparatively small amounts of the studied hydrocolloids to starch, one can achieve similar thermo-mechanical effects by the addition of gluten. Understanding these effects of hydrocolloids could contribute to the development of better quality gluten-free bread with optimized ingredient content.
... Continuing heat transfer results in irreversible changes ascertained with starch granule gelatinization ( Alcázar-Alay & Meireles, 2015 ). This includes the melting of starch crystallites, starch solubilization, and leaching out of starched granules, which can be seen as the loss of birefringence and increase in suspension viscosity ( Schirmer et al., 2015 ). The HPF had significantly higher (p ≤ 0.05) T o and T p compared to HPS. ...
Article
Full-text available
The aim of this work was to characterize morphological, crystalline property, physicochemical, functional, thermal, pasting, rheological properties, and in vitro digestibility of starch and flour from Plectranthus rotundifolius (Hausa potato). Chemical composition analysis showed a significant difference (p ≤ 0.05) between the Hausa potato starch and flour, and the amylose content of starch (30.44 %) was substantially greater than that of flour (20.57 %). SEM study showed that Hausa potato starch granule size varies from 3.31 μm to 6.61 μm having a morphology of some truncated circular shapes on a smooth granule surface. Hausa potato starch and flour exhibited a similar FT-IR pattern and A-type crystallinity. Howbeit, the relative crystallinity (obtained from XRD) of starch was significantly higher (p ≤ 0.05) than flour. The functional properties, including water and oil absorption capacity and solubility of flour, were significantly higher (p ≤ 0.05) than starch. RVA analysis observed that Hausa potato starch had a higher value in pasting properties compared to its flour. Enthalpy of gelatinization calculated from DSC showed that Hausa potato starch was significantly higher (p ≤ 0.05) than the flour. Hausa potato flour has a significantly greater (p ≤ 0.05) slowly digestible starch and resistant starch value than its starch. The study showed that starch and flour of Hausa potato significantly differed from each other. Better physicochemical and structural properties of Hausa potato starch can be explored as a non-conventional source of starch for various applications, and flour can be used as a useful functional ingredient in the food industry.
... Typical pasting profile and schematic representation of starch behaviour under heating and cooling(Schirmer et al., 2015). ...
Article
Collagen film (casings) obtained from acid-swollen collagen fibres is widely used as an alternative to natural casings for sausage production. However, collagen casings possess weak properties such as low mechanical properties (tensile strength and stiffness) and thermal stability compared to natural casings. Therefore, there is a need industrially to improve these properties. The main purpose of this work was to study the effects of polysaccharides on the properties of acid-swollen collagen pastes and films as a function of collagen paste concentrations (2.5 %, 3.5 % and 4 %wt/wt). In this work, polysaccharides dispersions: cellulose fibres of different length and waxy (WS) and high amylose (HAS) maize starch granules and molecular solutions: Hydroxypropylmethylcellulose (HPMC), Methylcellulose (MC), high molecular weight (GH), low molecular weight guar gum (GM) and Carboxymethylcellulose (CMC) were blended with acid-swollen collagen paste to fabricate collagen films with improved properties such as mechanical properties (tensile strength, stiffness and flexibility) and thermal stability. The viscoelastic of the blend pastes and denaturation of collagen was studied by rheological and thermal techniques. The pure and composite films were studied by sorption, mechanical, spectroscopic, structural, and thermal techniques. The focus of the first part of this study is to investigate the effect of uncharged and negatively charged molecular solutions at comparable low-shear viscosity on the viscoelastic and thermal properties of acid-swollen collagen paste. Dynamic rheological data indicated that the addition of non-charged hydrocolloids: HPMC, MC, GH and GM increased the storage modulus (G’) and loss modulus (G’’) of the acid-swollen collagen paste. By contrast, negatively charged CMC decreased the G’ and G” of the collagen pastes. At the level of addition of non-charged solutions (HPMC, MC, GH and GM) considered in this study, the denaturation temperature of collagen as determined by DSC was not affected while negatively charged CMC increased the denaturation temperature. Composite films containing blends of collagen paste with the individual molecular solutions were formed. Films were characterised for their mechanical, thermal, sorption and structural properties. Collagen/CMC films were not tested due to the difficulty in analysing the films. The thickness of the films increased and was dependent on the collagen concentration as well as the hydrocolloid concentration in the film network. Mechanical data revealed that the addition of hydrocolloids increased the tensile strength (TS), stiffness (YM), and elongation at break (EAB) of the films. Derivatised cellulose showed higher enhancement than the guars. Consistent with the mechanical data, DSC revealed an increase in peak temperature and a decrease in enthalpy of the films with the addition of the polymers. An increase in TS, YM, and EAB and an increase in peak temperatures were dependent on the collagen concentration. XRD data of the composite film showed a reduction in the intensity of the crystalline peak of collagen. FTIR spectra of the films helped to understand the structural changes and the interaction between the collagen and hydrocolloids. The thermal degradation temperature of collagen was not affected, as evidenced by the TGA curves. Furthermore, the composite films showed lower moisture uptake than the pure collagen films. The next study focused on investigating the effect of polysaccharide dispersions, cellulose with different fibre length, waxy and high amylose maize starches at comparable dispersed phase volume on the rheological and thermal properties of acid-swollen collagen paste. The dynamic rheological measurement revealed the dominant elastic behaviour (G’ > G’’) of the blend and control pastes. Cellulose fibres, waxy and high amylose starch granules increased the storage and loss modulus, and values increased with increasing collagen content. The starches exhibited a higher value due to the high concentration used. According to the DSC data, the denaturation of collagen and enthalpy of melting was not affected by the addition of the dispersions. On the other hand, on reheating the blend pastes, the starches lowered the enthalpy of the denatured collagen. Films were made from the blend pastes and were characterised for their mechanical, thermal, sorption and structural properties. The surface of composite films appeared rough because of the protrusion of the cellulose fibres and starch granules. The thickness of the films increased with the addition of the cellulose fibres and starch granules. Values increased with increasing levels of collagen and dispersions concentration in the film-forming paste. Reinforcing collagen films with cellulose fibres increased the mechanical properties (TS, YM and EAB) of the films. The mechanical properties of collagen with starch granules films could not be tested due to the brittleness of the films. DSC data showed that cellulose fibres increased the peak temperature of the films. By contrast, starch granules decreased the peak temperature. The enthalpy of the films was significantly reduced with the addition of cellulose fibres and starch granules. Collagen with starch granules films had the lowest enthalpy values. XRD data showed a decrease in the intensity of the crystalline peak of collagen in the blend films. The thermal stability of collagen was reduced, as evidenced by the TGA data. Additionally, the water uptake of the films decreased with the addition of cellulose fibres and starch granules. For the final study, the effect of collagen pastes (2.5%, 3.5% and 4 % wt) on the pasting properties of waxy (WS), high amylose (HAS) and normal (NS) maize starches were studied using Rapid Viscous Analyser (RVA) at conventional (up to 95 °C) and high-temperature (up to 140 °C) heating modes. Results showed that collagen pastes modified the pasting properties of the starches. At conventional heating mode, high amylose did not show a noticeable pasting profile. The pasting temperature of waxy starch was unaffected by the addition of collagen paste. By contrast, the addition of collagen paste lowered the pasting temperature of normal starches. The viscosities (peak, setback, and breakdown) of NS and WS increased. The final viscosity of WS decreased while that of NS increased with the increase in collagen paste concentration. When the samples are heated to temperatures 140 °C higher, HAS showed a noticeable pasting profile. The pasting temperature of HAS decreased with increasing levels of collagen paste addition. Peak and breakdown viscosities of NS, WS, and HAS increased with increasing collagen paste levels. In contrast, setback and final viscosities reduced.
... For the wheat starch there appeared to be two peaks, a first smaller peak at 104 °C and a second more pronounced peak at 132 °C, with the first peak presumably reflecting amylopectin melting and the second peak reflecting melting of amylose lipid complexes [63,64]. Peak viscosity reflects the swelling intensity [65]. Breakdown viscosity occurs because of granule rupture, which induces loss of paste viscosity [66]. ...
Article
Full-text available
The structure and physicochemical properties of starch isolated from the cotyledon and hull of faba beans and from wheat (as reference) were examined using 16 different methods. The amylose content in faba bean cotyledon and hull starch was 32% and 36%, respectively, and that in wheat starch was 21%. The faba bean cotyledon and hull starch were structurally alike both displaying C-polymorphic pattern, a similar degree of branching and similar branch chain length distributions. Wheat starch had a significantly greater prevalence of short amylopectin chains (DP < 12) and a higher degree of branching. Granules in both faba bean starches exhibited surface cracks and were more homogenous in size than the smoother wheat starch granules. Gelatinisation temperature was higher for the faba bean starches, likely as an effect of high amylose content and longer starch chains delaying granular swelling. Cotyledon starch produced pastes with the highest viscosities in all rheological measurements, probably owing to larger granules. Higher prevalence of lipids and resistant starch reduced the viscosity values for hull starch. For all starches, viscosity increased at faster heating rates. During the rheological analyses, the samples were exposed to different instruments, heating rates and temperatures ranges, differing from standard rheological procedures, which could help predict how different processing techniques effect the final starch textures. Graphical abstract
... Owing to its high absorption water, the addition of wheat bran reduces the content of free water in the system. As a result, more energy is required to disrupt the crystal structure of starch, which eventually increases the PT of whole-wheat flour [34]. Meanwhile, the fact that there was less free water contributed to the lower viscosity [10]. ...
Article
Full-text available
The particle size of wheat bran plays an important role in the quality of reconstituted whole-wheat flour and its products. The effects of wheat bran particle size on the quality of reconstituted whole-wheat flour and its cooked noodles were analyzed; the mean particle size (D50) of wheat bran ranged from 26.05 to 46.08 μm. Results show that the decreases in D50 of wheat bran induced the changes in the quality of whole-wheat flour and its noodles. Specifically, the damaged starch content, water absorption, and the solvent retention capacity of sodium carbonate and sucrose of whole-wheat flour increased at various degrees, while pasting viscosity decreased, and the gluten index and SDS-sedimentation volume increased first and then decreased. The cooking yield, cooking loss, and break rate of fresh noodles decreased first and reached a trough at D50 of 26.05 μm, and then increased. The adhesiveness of cooked noodles increased, the score of smoothness, taste, appearance, and color increased to a stable value, but the hardness, springiness, cohesiveness, resilience, firmness score, and elasticity score increased first and then decreased. These turning points of changing trends of indexes mostly occurred when the D50 of wheat bran was 26.51 μm. In conclusion, whole-wheat noodles with wheat bran of D50 of 26.51 μm addition exhibit better cooking, textural, and sensory properties than those with smaller or larger wheat bran. Excessive crushing of wheat bran not only costs highly in terms of energy, but also has a negative impact on the quality of the noodles.
... The T o of the samplewith 50% moisture content (MC) is slightly higher than that of the sample with 33.3% MC, which may be due to pyrodextrinization of starch at a low moisture content (Wang & Copeland, 2013). This may also be due to the fact that at lower moisture content, there is less free water in the starch system and thus the amount of energy available to destroy the crystal structure of starch is increased, resulting in a higher starting temperature (Schirmer et al., 2015). Overall with increasing water content, T o and T p gradually increased, while T c changed little. ...
Article
Full-text available
Abstract Using Bainong 365 wheat starch as raw material, starch samples were preheated in a RVA to simulate DSC heating profiles. The thermodynamic properties, long-range orderliness, short-range orderliness, and structure of wheat starch were determined by DSC, XRD, FTIR, LF-NMR and SEM to explore the phase transformation mechanism of Bainong 365 wheat starch at different water contents. The results show that at different moisture contents, when the endothermic transition temperature of starch samples determined by DSC was reached or exceeded, the enthalpy of starch was 0, all free water was converted into uneasy flowing water and bound water, and the surface structure of starch was severely damaged. At this time, starch was completely gelatinized, but the short-range and long-range ordered structures of starch determined by FTIR and XRD still existed and gradually decreased with increasing temperature. Therefore, it was concluded that the temperature range of the starch endothermic transition does not represent the temperature range of complete gelation of starch, and the structure destroyed by complete gelation of starch may not be simple short-range and long-range ordered molecular structures.
... These results could be attributed to the leakage of water and solubilized amylose, or amylopectin molecules promoted by temperature changes (cycles from 4 • C to 40 • C), causing changes in the interactions occurring in the gel network and the adhesive forces. This is in agreement with the findings reported by Schirmer et al. [45]. The authors stated that viscosity changes can be detected in starch-water systems in the temperature range between 30 • C and 50 • C as a result of the solubilization (leaching) of macromolecules. ...
Article
Full-text available
Starch-based hydrogels are natural polymeric structures with high potential interest for food, cosmeceutical, and pharmaceutical applications. In this study, the physical stability of starch-based hydrogels produced via high-pressure processing (HPP) was evaluated using conventional and accelerated methods. For this purpose, conventional stability measurements, namely swelling power, water activity, texture, and organoleptic properties, as well as microbiological analysis of rice, corn, wheat, and tapioca starch hydrogels, were determined at different time intervals during storage at 20 °C. Additionally, to assess the stability of these structures, accelerated tests based on temperature sweep tests and oscillatory rheological measurements, as well as temperature cycling tests, were performed. The experimental results demonstrated that the physical stability of starch-based HPP hydrogels was interdependently affected by the microorganisms’ action and starch retrogradation, leading to both organoleptic and texture modifications with marked reductions in swelling stability and firmness. It was concluded that tapioca starch hydrogels showed the lowest stability upon storage due to higher incidence of microbial spoilage. Accelerated tests allowed the good stability of HPP hydrogels to be predicted, evidencing good network strength and the ability to withstand temperature changes. Modifications of the rheological properties of corn, rice, and wheat hydrogels were only observed above 39 °C and at stress values 3 to 10 times higher than those necessary to modify commercial hydrogels. Moreover, structural changes to hydrogels after cycling tests were similar to those observed after 90 days of conventional storage. Data obtained in this work can be utilized to design specific storage conditions and product improvements. Moreover, the accelerated methods used in this study provided useful information, allowing the physical stability of starch-based hydrogels to be predicted.
... Native starch granules are relatively insoluble and non-dispersible. When heated in water, they undergo an irreversible order-disorder transition, characterized by taking up water, swelling, unfolding double helices, altering crystalline regions, losing birefringence, increasing solubility and developing viscosity (Schirmer et al., 2015;Tako et al., 2014;Wang & Copeland, 2013). Pretreatment using liquid hot water had gained attention due to no chemical used, with no or minor erosion to the equipment, and short reaction time (Varongchayakul et al., 2021). ...
Conference Paper
Bioethanol production from non-crop-based lignocellulosic material is gaining popularity across the world. Lignocellulosic materials are the most abundant renewable organic resources on the planet (200 billion tons per year) and can be converted to ethanol. Aquatic weeds have a rapid rate of reproduction and are high in cellulose and hemicellulose with low lignin content, making them a promising next-generation biofuel crop. In this work, the use of the elephant ear plant as a source of lignocellulosic feedstock for bioethanol production was studied. The experimental part included a physicochemical pretreatment using ash as a source of CaO in three different ratios: [1:0], [1:5], and [1:10], followed by hydrothermal and steam explosion treatment for 15 min. All treatment samples were measured for total sugar and reducing sugar content. The results showed that the fermentable sugars content was different among treatments. Enzyme-treated elephant ear plants had higher total sugars (6.51 ±0.27 mg/mL) than untreated samples (1.60 ±0.02 mg/mL). Moreover, the enzyme-treated elephant ear plant had a higher reducing sugar content than the untreated (5.40 ±0.11 mg/mL and 1.37 ±0.06 mg/mL, respectively). The ethanol potential for the fermentable sugars in the hydrolysate mixture was theoretically estimated. The highest efficient ethanol potential obtained was 2.75 ±0.06 mg/mL after 15 min under thermochemical pretreatment, with an ash ratio of [5:1] and 1% of cellulose for the hydrolysis step. The elephant ear plant has the potential to be a value-laden plant in the production of bioethanol.
... Native starch granules are relatively insoluble and non-dispersible. When heated in water, they undergo an irreversible order-disorder transition, characterized by taking up water, swelling, unfolding double helices, altering crystalline regions, losing birefringence, increasing solubility and developing viscosity (Schirmer et al., 2015;Tako et al., 2014;Wang & Copeland, 2013). Pretreatment using liquid hot water had gained attention due to no chemical used, with no or minor erosion to the equipment, and short reaction time (Varongchayakul et al., 2021). ...
Conference Paper
Biofuels have been regaining popularity due to the increasing price of non-renewable fuels and the larger carbon dioxide emissions. Biofuels are manufactured from plant products and are mainly composed of lignocellulose and starch. If these materials have been converted into biofuel, will be more beneficial than the currently available fuels. The aim of this investigation is to produce a large number of fermentable sugars for enhanced bioethanol production from tubers procured from northern Thailand. Before being hydrolyzed with cellulase enzymes, the tubers were chopped into small pieces (1-2 cm), dried in a solar oven, and powdered. The fermentable sugar content of Amorphophallus spp. (suweg) tuber increased from 2.6 g/L to 19.01 g/L after enzymatic hydrolysis, according to the data. Furthermore, the total sugar was 33.22 g/L at the optimal condition enzymes are an excellent way to speed up the hydrolysis process, and besides, biological methods are less expensive and more environmentally friendly than chemical alternatives. The enhanced fermentable sugars may be utilized in near future for bioethanol production to overcome depleting fossil fuels.
... The protein from buckwheat flour contributes to the replacement of gluten, which also influences the dough's rheological behavior, similarly to protein from amaranth [49]. The interactions between the different types of starch and protein impact the rheological characteristics of the dough, also affecting the pasting properties of the starch [50]. The protein weakening due to heat (C1-2) increased with BF addition. ...
Article
Full-text available
Buckwheat flour fractions with different particle sizes (PS), comprising various concentrations of valuable nutritional components, represent an opportunity to enhance refined wheat bakery products. The aim of this research was to assess the potential of buckwheat flour (BF) fractions (large, L > 300 μm, medium, 180 μm < M < 300 μm and small, S < 180 μm) to substitute refined wheat flour at 0, 5, 10, 15, and 20% in wheat bread dough and to establish the optimal amount for each fraction. The results revealed significant changes during different bread-making stages and on the finished product. A decrease in falling number index, water absorption, starch gelatinization, elastic modulus, and bread hardness with increasing PS was observed. The increase of BF amount led to an increase in dough development time, speed of protein weakening, gel starch stability, alveograph ratio, rheofermentation properties, maximum creep-recovery compliance, and bread hardness. The optimal values for falling number, mixing–heating–cooling dough parameters, dough biaxial extension, rheofermentation, storage and loss moduli, creep-recovery compliance, loaf volume, and bread hardness were obtained depending on PS based on the generation of predictive models. It was established that the best formulations, with respect to dough rheology and bread characteristics, included BF at 9.13% for large, 10.57% for medium, and 10.25% for small PS.
... Compared with the control group, the pasting temperature of pastes containing bran were higher. This could be due to the bran absorbed free water, so more energy was needed to destroy the crystal structure of starch granules to make them swell, resulting in an increase in the pasting temperature value (29). As the grain size of the bran increased, the peak viscosity of the flour decreased. ...
Article
Full-text available
Bran is the main by-product of wheat milling and the part of the grain with the highest Zn content. We investigated the effects of the particle sizes (coarse, D50 = 375.4 ± 12.3 μm; medium, D50 = 122.3 ± 7.1 μm; and fine, D50 = 60.5 ± 4.2 μm) and addition level (5–20%) of Zn-biofortified bran on the quality of flour and Chinese steamed bread. It was studied to determine if the Zn content of steamed bread could be enhanced without deleterious effects on quality. Dough pasting properties, such as peak viscosity, trough viscosity, final viscosity, breakdown, and setback, decreased significantly as the bran addition level was increased from 5 to 20% but did not significantly differ as a result of different bran particle sizes. Bran incorporation significantly increased hardness, gumminess, chewiness, and adhesiveness, whereas the springiness, cohesiveness, and specific volume of steamed bread decreased with the increase in bran addition. The optimal sensory score of steamed bread samples in the control and Zn fertilizer groups were obtained under 5% bran addition resulting in comparable flavor, and texture relative to control. Meanwhile, the Zn content of the steamed bread in the Zn fertilizer group was 40.2 mg/kg, which was 55.8% higher than that in the control group. Results indicated that adding the appropriate particle size and amount of bran would be an effective and practical way to solve the problem of the insufficient Zn content of steamed bread.
... Processing that disrupts the integrity of starch granules may also influence starch digestibility, for example native starch with intact grains is extremely resistant to hydrolysis, whereas milling/grinding increase the surface area and makes the starch molecules more susceptible to enzyme hydrolysis (Mishra et a., 2012;Singh et al., 2010). Starch become more susceptible to enzymic reactions when gelatinized under heat treatment in the presence of water, for example during extrusion (Schirmer et al., 2015). Hence, the starch-water ratio determines the extent of starch gelatinization and therefore becomes an important determinant of the starch digestibility rate of processed food (Singh et al., 2010). ...
Thesis
Full-text available
This study focused on modification of rye bran to produce high fibre extruded cereal foods with a good texture and structure. Rye bran addition during extrusion is challenging due to high levels of insoluble dietary fibre, which leads to less expanded products and a hard texture. Bran modification by particle size reduction or fermentation significantly improved both the structural and textural properties of extrudates. Moreover, optimization of the processing parameters such as increasing the screw speed, lowering the water feed rate, as well as the use of in-barrel hydration regimens further improved the textural properties. The applicability of rye bran in extruded products could thus be improved by particle size reduction and fermentation. The extruded food structure and texture had a direct effect on the mastication and bolus formation process in the mouth. A hard and dense extrudate structure required more mastication effort than a crispy structure. Crispy and porous structures easily disintegrated in the mouth and produced smaller bolus particles than a hard and dense structure. A smaller particle size of the bolus was associated with increased starch hydrolysis. The bolus particle size was more effective than the matrix composition in altering the starch digestibility. Increased dietary fibre intake via appealing snack products could help reduce chronic diseases. Knowledge obtained in this thesis on cereal matrix formation and digestion and the effects of added dietary fibre on the structural and textural properties of extruded solid foams will help the food industry to develop healthy and appealing products. Understanding process-structure-digestibility relationships of high fibre extruded matrices is essential for designing health promoting foods.
... Therefore, it is possible to assume that the moisture retention by soluble fiber resulted in increased shear and temperature values (Jin et al., 1994). This limitation in available moisture may also explain the reduction in starch gelatinization observed after CPP inclusion, as starch hydration, swelling, and melting are necessary for proper cooking (Schirmer et al., 2015). Starch gelatinization, however, was not affected by OF. ...
Article
Citrus pulp pellets (CPP) and orange fiber (OF) are coproducts of the citrus juice industry. OF is a novel fiber source that contains elevated amounts of soluble fiber and has not yet been studied in dog nutrition. The objectives of this study were to evaluate the inclusion of CPP and OF in dog foods and their effects on the extrusion parameters, the coefficient of total tract apparent digestibility (CTTAD) of nutrients, fermentation end products, and palatability. A control diet (CO) without an added fiber source tested was formulated, and the experimental diets were composed of 30 g/kg, 60 g/kg and 120 g/kg CPP or 60 g/kg OF inclusion (as-fed basis). Extrusion parameters were recorded to determine extruder energy balance and kibble macrostructure. Thirty beagle dogs (3.2 ± 0.7 years; 12.4 ± 1.5 kg body weight) were distributed in a randomized block design with 6 dogs per group to evaluate the CTTAD of nutrients and the fermentation products in feces. The results were analyzed by analysis of variance, and means were compared by polynomial and orthogonal contrasts. The inclusion of CPP and OF reduced motor amperage (P<0.001), mass pressure (P=0.002), and specific mechanical energy transference (P<0.001). Kibble macrostructure was affected by a decrease in expansion and an increase in hardness by CPP and OF inclusions (P<0.001). Starch gelatinization was reduced by CPP (P<0.001) but not by OF inclusion (P>0.05). Total dietary fiber (TDF) intake increased (P<0.001) with the addition of CPP, with a linear reduction in CTTAD of nutrients and energy (P<0.05). The OF treatment, however, presented similar CTTAD values of DM and CP to those of the CO diet (P>0.05). The TDF CTTAD was higher for 60 g/kg OF than for 60 g/kg CPP (P=0.028). The fecal pH decreased, and total short-chain fatty acids (SCFA), acetic acid, butyric acid, and lactate concentrations increased with CPP and OF inclusion (P<0.05). However, the diet supplemented with OF induced the production of feces with a lower pH and higher total SCFA concentrations than those of feces produced from CPP inclusion (P<0.001). The OF diet presented a higher preference (65%) than the CO diet (35%) by dogs (P<0.05). The CPP and OF were fermentable fiber sources, increasing SCFA and butyric acid concentrations in feces. The OF was more fermentable than CPP, with a limited impact on kibble formation, starch cooking, and CTTAD of nutrients and showing good acceptance on diets by dogs.
... Hardness decrease Studies on the degree of starch gelatinization at variable cooking times in pasta [22] indicated that only 80% of starch was gelatinized at the cooking time suggested by the pasta producer, while 90% starch gelatinization was reached only in an overcooked product. In this respect, a complete starch gelatinization is not required to consider a product cooked [23]. Therefore, we can expect starch to be mainly gelatinized in BR at the inflection point where water uptake is reduced, but it can be considered cooked over a larger range of moisture contents. ...
Article
Full-text available
Despite several nutritional benefits of brown rice (BR) its consumption remains limited compared to white rice. Two of the major barriers to its consumption are long cooking time and limited shelf life. However, those two hurdles can be overcome through the development of shelf-stable BR pouches to create new ready-to-eat (RTE) products, a food category that is gaining important market shares. Nevertheless, scarce information is available on the production and shelf-life stability of ready-to-eat BR products. The first objective of this study was the determination of the optimal moisture range to fully cook BR. The second objective was to determine the effect of moisture content and storage time on two fundamental parameters for consumer’s acceptance of rice: color and texture. Three RTE BR pouches with moisture contents of 54%, 57% and 60% were produced and texture and color were evaluated after 1 year of storage. Significant changes in hardness and stickiness were reported during long-term storage. Moisture content negatively affected hardness and positively affected stickiness. Furthermore, storage time and moisture showed a significant effect on rice color. The present results provide information that will be useful to design new RTE meals to promote brown rice consumption.
... Continuous heating of starch paste, after it reaches its peak viscosity results in a decline in its viscosity. This decline is termed as breakdown of starch paste, which is the outcome of extensive solubilization and fragmentation of starch granule structures to an extent that they are inadequate to withhold large volume of water[139][137].but the characteristics of formed gel depends on the properties of starch[140][141]. Freezing and thawing of gel has a negative impact on food texture. ...
Thesis
Roots and Tuber crops plays an eminent, countless and complex part in feeding the world. These crops have the potential to eradicate poverty and improve food security. Starch is the principal component of roots and tuber crops. The significance of starch as a raw material in both food and non-food industries are increasing. In present study efficiency of ultrasound assisted extraction (UAE) to increase the yield of starch and polyphenols from lontan (Canna and Cassava) crops were analysed along with its influence on the physiochemical properties of extracted compounds. Extraction parameters (Temperature, time, solid: liquid ratio) were optimized through Box Behnken response surface design (BBD). Physiochemical and functional properties of starch and polyphenols were investigated through SEM, swelling and solubility index, oil and water absorption index, Total polyphenol yield, DPPH and ORAC assay. Starch yield obtained from canna and cassava at the optimum extraction conditions (Canna: temperature 40°C, time 10 min, solid: liquid ratio 1:30 g/ml; Cassava: temperature 40°C, time 10 min, solid: liquid ratio 1:25 g/ml) were 19.81% and 16.51% respectively. Obtained starch yield was found to be significantly higher than the yield attained through conventional extraction method without any significant or adverse changes in the physicochemical and functional properties. Total polyphenol yield from canna and cassava rhizome was 1061.72 mg GAE/&100g and 7644.46 mg GAE/&100g respectively. Total polyphenol yield obtained through UAE was found to be significantly higher than conventional method. Antioxidant activity of bioactive compounds analysed through DPPH and ORAC was found to be directly proportional to the attained polyphenol yield. From the obtained results it can be observed that UAE has the efficiency to increase the yield of starch and polyphenols without altering the properties of isolated compounds.
... Specifically, pre-gelatinization is a cheap and efficient technology for enhancing flour starch properties (for example, the ability to form paste in cold water) and available food nutrients such as antioxidants, dietary fibres, minerals, by diminishing the anti-nutritional factors in cereals and legumes [30][31][32][33]. The physical method of legume and cereal starch modification owed to pre-gelatinization of starches has been shown to influence the functionality of starches [34,35,36]. The pre-gelatinization of cereal and legume starches is usually accompanied by some transformations such as loss of crystallinity, disruption of starch granule structure, granule swelling, among others [37,38,39]. ...
Article
Full-text available
The progress towards exploring the potentials of underutilized indigenous food sources via product development to curb food wastage and agro-food extinction is a way of attaining food nutrition and security within a region. In this context, a comparative study involving some functional properties of complementary food from some underutilized foods (millet, African yam bean, and jackfruit) was carried out. Briefly, millet, African yam bean, and jackfruit were subjected to series of processing treatments such as malting, pre-gelatinization, drying, and milling, followed by blending into various ratios to obtain different samples of composite flours as a complementary food. From these, the functional properties, that is, water absorption capacity (WAC), loose bulk density (LBD), packed bulk density (PBD), foam capacity (FC), swelling index (SI), dispersibility, wettability, and sinkability were determined. Results showed that malting and pre-gelatinization influenced the intrinsic functional properties of the flour blends. In addition, composite flours containing malted samples had significantly lower (p<0.05) dispersibility, SI, WAC, LBD, and PBD, but significantly higher (p<0.05) wettability and sinkability. The variations in flour substitution showed no impact on the flour functionality except for SI and dispersibility. All composite flours exhibited an appreciable level of functionality and suitability to be used as a complementary food for weaning purposes. Overall, this research has demonstrated the potentials of utilizing millet, African yam bean, and jackfruit as sustainable nutrient-dense food materials for the production of complementary food.
... A starch paste is a diphase system of amylose (a continuous phase colloidal amylose solution) and starch granules composed mainly of amylopectin (a dispersed phase). Rheological properties of such systems depend on many factors, including the type of starch, the starch content, the paste preparation method, and the measurement temperature [44,48,49]. ...
Article
Full-text available
The aim of this study was to evaluate the effect of the temperature (15 or 45 °C) and the duration (15–120 min) of the modification process on the selected physicochemical, thermal, and rheological properties of phosphorylated potato starch. The modified starches contained 93.6–98.2 mg P/100 g (dry weight basis, d.w.b.). Phosphorylation caused color changes with a total color difference between the starches below 0.55, but these changes were less than those that were recognizable by the human eye. The thermal analysis showed two opposite processes appearing during the modification: the loosening of the structure (dominant among starches obtained at 15 °C) and the strengthening of the structure (dominant among starches obtained at 45 °C). The higher phosphorylation temperature reduced native starch recovery from 140% to 87–116% and increased the hysteresis loop area from −169 to 1040. All of the pastes made from the modified starches showed a weaker tendency for retrogradation (during 21 days of storage) than native starches. The results of the regression analysis conducted between the properties of the starch pastes obtained at 45 °C indicated that the modification time appeared to be a better indicator of the rate of modification progress than the phosphorus content. The PCA (principal component analysis) results made it possible to distinguish starch phosphates obtained at 15 °C from those obtained at 45 °C and those from natural starch.
... Gelatinization temperatures and enthalpies associated with starch gelatinization varied among the GF flours (Table 6). The variation in the thermal properties among the different flours are influenced by some factors such as: size of the starch granule, molecular structure of the amylopectin (branch, length and weight), starch, protein and dietary fiber content, as well as the presence of other compounds [63]. During starch gelatinization, the helix structure and crystallinity of the starch is lost and the granule is disrupted. ...
Article
Full-text available
This study characterized and compared 13 gluten-free (GF) flours (rice, brown rice, maize, oat, millet, teff, amaranth, buckwheat, quinoa, chickpea, gram, tiger nut, and plantain) for their nutritional and functional properties. For all GF flours investigated, starch was the major component, except for gram, chickpea, and tiger nut flours with lower starch content (<45%), but higher fiber content (8.8–35.4%). The higher amount of calcium, magnesium, zinc, potassium, phosphorus, similar values for iron and lower content of sodium in gram, makes this flour a good alternative to chickpea or other GF flour to develop healthier food products. Amaranth flour had a high protein digestibility, while tiger nut and millet flours were less digestible. Gram, chickpea, quinoa, buckwheat, and oat flours fulfilled amino acids recommendation for daily adult intake showing no limiting amino acid. Total polyphenolic content and antioxidant capacity showed higher values for buckwheat, followed by quinoa and maize flours. Gram, chickpea, maize, and quinoa flours are good candidates to improve health conditions due to lower saturated fatty acid content. The findings of this study provide useful insights into GF flours and may contribute to the development of novel gluten-free products like bread, cookies, or pasta.
... Gelatinisasi pati adalah gangguan tatanan molekuler dalam granula pati dimanifestasikan dalam perubahan sifat yang tidak dapat balik seperti daya gelembung granula, pelelehan kristalit alami, hilangnya birefringence, dan daya larut pati (Maaruf et al., 2001). Gelatinisasi pati dapat dipelajari melalui teknik rapid visco analyzer (RVA) atau differential scanning calorimetry (DSC) dan rheometer (Schirmer, Jekle and Becker, 2015). Kapasitas menggelembung pati sagu relatif sama dengan pati singkong tetapi lebih tinggi dibandingkan pati kacang-kacangan dan jagung. ...
Book
Para peneliti Bidang Perikanan memaparkan hasil penelitian dan pemikirannya seputar: Pengolahan Ikan dan Promosi Maluku sebagai Center of Fish Product; Pengelolaan Perikanan Tangkap Maluku Untuk Menjamin Ketersediaan Stok Ikan Nasional; dan Marikultur: Potensi dan Pengembangan Melalui Akuakultur Sistem Keramba Jaring Apung (KJA) di Maluku. Mereka memotret realitas kekayaan sumber daya perikanan dan kelautan Maluku yang dapat dimanfaatkan secara maksimal dan berkelanjutan dengan tawaran-tawaran rekomendasi yang ada. Para peneliti Bidang Kesehatan memaparkan hasil penelitian dan pemikiran mereka tentang: Incredible Future of Maluku Province with Herbal Medicines dan Uji Toksisitas Terhadap Bahan Makanan Berbahan Dasar Crassostrea (Rock Oyster) Sebagai Obat Cacing Lokal di Daerah Pesisir Pulau Ambon. Potret Bidang Kesehatan ini hendak menunjukkan bahwa Maluku kaya akan sumber daya alam yang potensial bagi pengembangan bidang kesehatan terutama bahan baku obat dari darat dan laut. Penelitian-penelitian seperti ini patut didukung terutama di saat banyak pihak sementara berlomba-lomba menemukan bahan-bahan baku obat dari alam di penjuru dunia. Para peneliti Bidang Pertanian menyampaikan hasil penelitian dan pemikiran mereka dengan judul: Pati Sagu: Potensi Pemanfaatan dan Nilai Ekonomisnya; dan Model Pengembangan Kluster Inovasi Berbasis Produk Unggulan Daerah Cengkih. Diakui bahwa Sagu dan Cengkih bukan saja merupakan hasil alam dari Maluku tetapi telah menjadi simbol sosial budaya Maluku. Banyak orang Maluku yang mengaku hidup dari Sagu dan Cengkih. Para peneliti berupaya memaparkan tentang Sagu dan Cengkih dari sisi pertanian namun menawarkan pemanfaatannya dari sisi ekonomi.
... S4, and movie S3). Together with irreversible gluten denaturation (34) and starch gelatinization (35), the morphing of flour dough became irreversible after cooking compared with the PDMS. Even with a prolonged hydration time (2 hours at 90°C), the bending curvature of the dough only displayed a 20% decrease. ...
Article
Full-text available
Morphing structures are often engineered with stresses introduced into a flat sheet by leveraging structural anisotropy or compositional heterogeneity. Here, we identify a simple and universal diffusion-based mechanism to enable a transient morphing effect in structures with parametric surface grooves, which can be realized with a single material and fabricated using low-cost manufacturing methods (e.g., stamping, molding, and casting). We demonstrate from quantitative experiments and multiphysics simulations that parametric surface grooving can induce temporary asynchronous swelling or deswelling and can transform flat objects into designed, three-dimensional shapes. By tuning the grooving pattern, we can achieve both zero (e.g., helices) and nonzero (e.g., saddles) Gaussian curvature geometries. This mechanism allows us to demonstrate approaches that could improve the efficiency of certain food manufacturing processes and facilitate the sustainable packaging of food, for instance, by creating morphing pasta that can be flat-packed to reduce the air space in the packaging.
... Thus, the water holding capaci-ty will increase and reduce shrinkage. The starch content in analog meat forms a gel through the gelatinization process, causing the sausage texture more compact (Schirmer, Jekle, & Becker, 2015). ...
Article
This research was conducted to make chicken sausage substitution using analog meat from gluten, soy protein isolate, wheat flour, Anjasmoro soybean, and gembili tuber flour to reduce chicken meat used and produce sausages with the same quality. The purpose of this study was to determine the sausage’s physical, chemical, and sensory properties. The formulation of chicken sausage with analog meat substitution used a completely randomized design method with a single factor (chicken meat and analog meat ratio), with five treatments and each treatment was repeated three times. The five treatments are P1 = 90% chicken meat : 10% analog meat, P2 = 80% chicken meat : 20% analog meat, P3 = 70% chicken meat : 30% analog meat, P4 = 60% chicken meat : 40% analog meat and P5 = 50% chicken : 50% analog meat. The results showed that the substitution of chicken meat with analog meat had a significant effect on the physical, chemical, and sensory properties of chicken sausage. The results show that 70% chicken meat and 30% analog meat is the best treatment. Keywords: analog meat, chicken sausage, substitution Abstrak Penelitian ini dilakukan untuk membuat substitusi sosis daging ayam menggunakan daging analog dari gluten, isolat protein kedelai, tepung terigu, kedelai Anjasmoro dan tepung umbi gembili. Sehingga dapat mengurangi penggunaan daging ayam dan dapat menghasilkan sosis dengan kualitas yang sama. Tujuan dari penelitian ini adalah untuk menentukan sifat fisik, kimia dan sensorik sosis. Formulasi pembuatan sosis daging ayam dengan substitusi daging analog, menggunakan metode rancangan acak lengkap dengan faktor tunggal (rasio penambahan daging ayam dan daging analog) dengan lima perlakuan serta masing - masing perlakuan diulang tiga kali ulangan. Lima perlakuan tersebut ialah P1 = 90% daging ayam : 10% daging analog, P2 = 80% daging ayam : 20% daging analog, P3 = 70% daging ayam : 30% daging analog, P4 = 60% daging ayam : 40% daging analog dan P5 = 50% daging ayam : 50% daging analog. Hasil penelitian menunjukkan bahwa susbtitusi daging ayam dengan daging analog berpengaruh nyata terhadap sifat fisik, kimia, dan sensorik sosis ayam. Hasil penelitian menunjukkan bahwa perlakuan70% daging ayam dan 30% daging analog adalah perlakuan terbaik. Kata Kunci: daging analog, sosis daging ayam, substitusi
Article
The aim of this study was to investigate the effects of wheat bran dietary fibre (WBDF, 3%, 6%, 9%, 12% and 15%) and raw wheat bran (RWB, 6%, 12%, 18%, 24% and 30%) on the flour and dough properties. Under the same content of TDF in blended flour, WBDF could better inhibited the starch retrogradation. The dough with WBDF possessed higher water absorption, longer development and stability time, more excellent mechanical resistance during mixing but worse when heating. Both storage modulus (G′) and loss modulus (G″) of dough containing WBDF were higher than those of RWB, while loss tangent (tanδ), creep strain and recovery strain were opposite, WBDF more effectively improved the viscoelasticity, strength of dough and enhanced the solid elastic behavior of dough. The microstructure showed that RWB destroyed the continuity and order of gluten network more seriously than WBDF, led to more starch granules leaking out. This study showed that purified WBDF represented better performance than RWB on the whole, and possessed more potential to develop high-fibre wheat flour products.
Article
Polysaccharides, as natural, biodegradable, biocompatible, non-allergen, and non-toxic polymers, have been utilized as potent ingredients in various food and pharmaceutical applications owing to their outstanding aptitude in stabilizing emulsions/foams as well as generating gels/films/viscous dispersions. However, apart from these unique attributes, the widespread application of polysaccharides has been challenged by some obstacles resulted from their low thermal/shear resistibility, retrogradability as well as diminished gel/paste transparency. Hitherto, to tackle these shortcomings various enzymatic, chemical, and physical modification approaches have been developed. Taking advantages from being both a physical and non-thermal approach, High hydrostatic pressure (HHP) has been a promising tool for introducing novel applications to the realm of food. HHP is a compelling approach capable of manipulating structure and physicochemical attributes of polysaccharides comparable to the conventional thermal/chemical methods. It also demonstrated a prodigious potential in enhancing the nutritional attributes of modified components either through preserving the thermo-sensitive ingredients or enhancing the resistant starch content of starches. Accordingly, the application of HHP for manipulating chemical, physical, technofunctional and nutritional characteristics of various polysaccharides has been the focus of numerous researches. The basic theory of HHP as well as its influence on different physicochemical/nutritional attributes of polysaccharides are reviewed in this study, in detail.
Chapter
The application properties of starches are more common in industrial use than in research application where starch properties are mostly concerned. This chapter aims to guide the reader on the evolution of various parameters used to measure these properties of starch. Among others, this chapter conceptualizes and highlights viscosity as the most important application property. To measure viscosity, the RVA is the mostly used device for research, but we suggest some more simple equipment for industries, as Ford cup and Brookfield. The DSC provided more reliable results of temperatures involved in the gelatinization process. The author highlights the occurrence of complexation of amylose with phenolic compounds and possible arrangements with mucilage, as factors capable of influencing the properties of starches extracted from underground raw materials.
Article
The purpose of this study was to determine the effect of psyllium and cellulose fiber additions on starch digestion behavior, as well as the structural and textural characteristics of bread and cracker samples. Fiber-added samples were created by replacing 10% of the wheat flour in the recipes with fibers. Fibers reduced the porosity of the bread samples, increased their hardness and chewiness, and decreased the hardness of the crackers. Due to its high water-holding capacity, psyllium fiber interfered more than cellulose fiber with the formation of a gluten network and dough structure. At this concentration, psyllium fiber was effective at slowing the digestion of bread and crackers, whereas cellulose fiber had no effect. Psyllium fiber inhibited starch digestion by acting as a physical barrier and limiting enzyme mobility. Due to the structural differences between bread and crackers, they digested differently. The findings indicated that variations in the development of food structures caused by processing methods and the solubility of the fibers used could have a differential effect on starch digestion. Across the board, food processing methods, ingredients, and textural characteristics can all have an effect on starch digestion.
Chapter
Starch is omnipresent in plant material and is the most important polysaccharide as well as storage polymer. Starch undergoes various transformations during food processing. Heating of starch in presence of water results in gelatinization which is accompanied by granule breakdown, loss of ordered structure, and loss of optical birefringence. Low temperature favors the re-association of disrupted chains of amylose and amylopectin in a process known as retrogradation. These changes are very much affected by the nature of starch and the amylose to amylopectin ratio. Therefore, it is important to study or monitor the various changes under the influence of various treatments to expand its commercial value. Starch possesses substantial nutritional, pharmaceutical, and industrial importance owing to its distinctive physical, chemical, and functional characteristics. Starch owns varied functional properties and applications in the food industry. However, the native starches lack desired functional characteristics for anticipated applications in the food industry. To increase its commercial significance, the functional properties of starch can be upgraded under the stimulus of several physical, chemical, and enzymatic techniques. Alterations in the structure of starch molecules initiated by various treatments are characterized as modifications. The starch structure is sensitive to high temperature, very high and low pH, high pressure, osmotic pressure, electric field, plasma, sonic waves, microwaves, irradiation, ozone, mechanical stress, various chemicals, and enzymes. These alterations may employ either desirable or undesirable changes in the structure and functionality of starch. Therefore, an appropriate selection of modification techniques concerning cost economics, environmental factors, and efficiency is required to attain targeted improvements in functional characteristics. A practical alternative to chemical and heat-induced alterations is non-thermal treatments that are clean, environmental friendly, more efficient, free from toxic residues, and are sustainable. These techniques are of most interest to the food scientist in the present times. Also, the structural transformations of starch caused by various methods are important to visualize the effectiveness of the process and can be studied by a range of available methods based on different principles such as microscopic, spectroscopic, differential scanning calorimetry, rheological, X-ray diffractions and chromatographic methods, etc. With the scientific and technological interventions, newer techniques for starch modification are being introduced to achieve the targeted characteristics in a simple and more practical approach.
Article
Starch is a major contributor to the carbohydrate portion of our diet. When it is present with water, it undergoes several transformations during heating and/or cooling making it an essential structure‐forming component in starch‐rich food systems (e.g., bread and cake). Time domain proton nuclear magnetic resonance (TD 1H NMR) is a useful technique to study starch–water interactions by evaluation of molecular mobility and water distribution. The data obtained correspond to changes in starch structure and the state of water during or resulting from processing. When this technique was first applied to starch(‐rich) foods, significant challenges were encountered during data interpretation of complex food systems (e.g., cake or biscuit) due to the presence of multiple constituents (proteins, carbohydrates, lipids, etc.). This article discusses the principles of TD 1H NMR and the tools applied that improved characterization and interpretation of TD NMR data. More in particular, the major differences in proton distribution of various dough and cooked/baked food systems are examined. The application of variable‐temperature TD 1H NMR is also discussed as it demonstrates exceptional ability to elucidate the molecular dynamics of starch transitions (e.g., gelatinization, gelation) in dough/batter systems during heating/cooling. In conclusion, TD NMR is considered a valuable tool to understand the behavior of starch and water that relate to the characteristics and/or quality of starchy food products. Such insights are crucial for food product optimization and development in response to the needs of the food industry.
Article
High-moisture extrusion cooking (HMEC) is an efficient method for converting proteins and polysaccharides into fibrous structure that is used in the industrial production of meat analogs. The purpose of this review is to systematically evaluate current knowledge regarding the modification of protein structure including denaturation and reassembly upon extrusion processing and to correlate this understanding to the structure of the final products. Although there is no consensus on the relative importance of a certain type of bond on extrudates' structure, literature suggests that, regardless of moisture level, these linkages and interactions give rise to distinctive hierarchical order. Both noncovalent and disulfide bonds contribute to the extrudates' fibrous structure. At high water levels, hydrogen and disulfide bonds play a dominant role in extrudates' texture. The process parameters including cooking temperature, screw speed, and moisture content have significant albeit different levels of impact on the texturization process. Their correlation with the ingredients' physiochemical properties provides a greater insight into the process-structure-function relationship of meat analogs. The tendency of protein and polysaccharide blends to phase separate rather than produce a homogeneous mix is a particularly important aspect that leads to the formation of fibrous layers when extruded. This review shows that systematic studies are required to measure and explain synergistic and competitive interactions between proteins and other ingredients such as carbohydrates with a focus on their incompatibility. The wide range of plant protein source can be utilized in the HMEC process to produce texturized products, including meat analogs.
Article
The property changes of sorghum starch during multiple cycles of gelatinization and fermentation were studied. This study simulated the gelatinization and fermentation process of raw starch in strong-flavor Baijiu production (Sorghum as raw material, the distillers' grains as a control). The results showed that the starch content of the same batch of sorghum after five cycles of gelatinization and fermentation was 9.98% (Cannot continue to be used for fermentation), and about 60% of the starch was consumed in the first three cycles of gelatinization and fermentation. The gel properties of sorghum starch gradually decreased during fermentation but slightly increased after gelatinization. After five cycles of gelatinization and fermentation, the sorghum starch has a uniform size and a thin and small fragment structure. At the same time, sorghum starch does not form new groups. The recrystallization of starch caused by multiple cycles of gelatinization and fermentation increased the onset gelatinization temperature (from 61.6 to 114.4 °C), peak gelatinization temperature (from 78.5 to 139.5 °C), and gelatinization enthalpy (from 7.980 to 17.121 J/g) of sorghum starch. The crystalline structure of sorghum starch changed from the initial type A to type A + V, type A + B + V, and finally to type B.
Article
Legumes are members of the Fabaceae family, whose seeds have been a staple of human sustenance since prehistoric times. They have high contents of carbohydrates, proteins, dietary fiber, vitamins, and minerals and a wide range of non-nutrient bioactive compounds that impact positive health. Most legume polysaccharides are principally made up of starch. Legume starches are rich in amylose and show limited swelling power and poor water dispersion. They showed higher retrogradation properties than cereal starches due to more amylose content and produced higher resistant starch, consequently decreasing the glycemic index. Further, these starches shave strong bondings, confirming their high gelatinization transition temperatures and enthalpies. This review highlighted developments in the morphological, pasting, structural, thermal, crystallinity, and digestibility properties of legume starches. The differences in granule sizes, gelatinization transition temperatures, gelatinization enthalpies, peak viscosities, pasting temperatures, and setback viscosities ranged from 4-80 µm, 50.80-142.400C, 4.67-15.30 J/g, 390.24-14380.00 cP, 70.30-88.550C, and 113.04-944.00 cP, respectively among the legume starches. Understanding the properties of legume starches provides insights into the novel direction of their utilization. Further, there is a bold attempt to compare legumes to starches from different botanical sources.
Article
Despite the excellent nutritive potential, millets remained underutilized due to different factors including the presence of anti‐nutritional factors, lack of optimized processing technologies and compromised techno‐functionality of the raw flours. Bioprocessing techniques such as soaking, germination, enzymatic hydrolysis, and fermentation are the natural methods for enhancing the compositional and functional characteristics of the millets. They lead to synthesis and release of components from the wall of polysaccharides and unfolding of proteins due to the action of degrading enzymes that are produced during the bioprocessing of millets. The objective of the present article is to comprehensively review the recent investigations focusing on modulations in the compositional parameters, bio‐ and techno‐functional attributes of millets due to different biological processing treatments. Available literature suggested these treatments caused significant changes in the protein starch matrix, phytochemical constituents, rheological properties, hydration profile, anti‐nutritional factors, in vitro starch and protein digestibility, structural and molecular modification.
Article
Starch gelatinization is a crucial process in determining both texture and nutrition properties of starch-based foods, while its complex nature is still not fully understood. Kinetics modeling has been recently developed for understanding starch gelatinization under both limited and excessive water content. Amylose with different chain lengths has distinct effects on starch gelatinization temperatures and enthalpy by interacting with amylopectin chains in semi-crystalline lamella. Moisture is a crucial factor in determining starch gelatinization property, with new evidence suggesting that different groups of amylopectin-amylopectin or amylose-amylopectin double helices were involved for multi-endothermic gelatinization peaks under limited moisture content. The presence of salts, sugars, protein, lipids and non-starch polysaccharides can affect starch gelatinization through various mechanisms. All these new insights and future directions in terms of better understanding starch gelatinization property were summarized. This information could help develop new generations of foods with desirable properties through a better understanding of starch gelatinization process.
Preprint
Full-text available
The property changes of sorghum starch during multiple cycles of gelatinization fermentation were studied. This study simulated strong-flavor Baijiu’s gelatinization and fermentation process (The sorghum as raw material, the distillers' grains as control). The results showed that the starch content of the same batch of sorghum after five cycles of gelatinization and fermentation was 9.98% (Cannot continue to be used for fermentation), and about 60% of the starch was consumed in the first three cycles of gelatinization and fermentation. The gel properties of sorghum starch gradually decreased during fermentation but slightly increased after gelatinization. After five cycles of gelatinization and fermentation, the sorghum starch has a uniform size and thin and small fragment structure. At the same time, sorghum starch does not form new groups. The recrystallization of starch caused by multiple cycles of gelatinization and fermentation increased the onset gelatinization temperature (from 61.6 to 114.4 °C), peak gelatinization temperature (from 78.5 to 139.5 °C), and gelatinization enthalpy (from 7.980 to 17.121 J/g) of sorghum starch. The crystalline structure of sorghum starch changed from the initial type A to type A+V, type A+B+V, and finally to type B.
Chapter
Plant-based alternatives to dairy foods such as cheese, yogurt, butter, and ice cream are important products in the plant-based food portfolio. The central ingredient in conventional dairy products is milk. In contrast, dairy alternatives utilize many different ingredients to successfully create desired physicochemical properties, textures, and flavours that mimic those of milk products. This chapter will highlight the most important ingredients and the functionality needed to obtain such properties in cheese, yogurt, ice cream, whipping cream, and butter alternatives. Processes and parameters will be described that are important for the production of these dairy analogs. The chapter will also highlight some essential sustainability and health aspects that need to be considered when designing products that are intended as dairy alternatives.
Article
In the past research, pectin was added to starch to ameliorate properties, but there is no relevant review to explain and clarify. Therefore, this article reviews the formation, structure and properties of starch-pectin blend, and proposes the potential prebiotic properties of starch-pectin blend. The interaction between starch-pectin blend is mainly a non-covalent interaction based on hydrogen bonds, pectin molecules interact with starch mainly through side chains. This effect leads to the higher crystallinity and the more short-range ordered structures in the starch, such as single helix and double helix ratios, ultimately, it increases the content of resistant starch (RS) and slow-digestible starch, and reducing the digestibility of starch. At the same time, we believe that the resistance mechanism of starch-pectin mixture is similar to type 1 and type 5 RS. The resistance not only comes from the protection of pectin on starch and the inhibition effect of pectin on digestive enzymes, but also the complex formed by the hydrogen bonding of starch and pectin. The blend may have the synergistic probiotic effect of single RS and pectin.
Article
Pentlandite is very important to the mining industry since it is the main source of metallic nickel. However, its separation from hexagonal pyrrhotite by froth flotation is challenging due to their similar floatabilities, and inefficiencies in this process generate environmental issues caused by emissions of sulfur oxide gases during the pyrometallurgy of nickel concentrates. Although successful, the current pyrrhotite depressant (diethylenetriamine - DETA) is also harmful to the environment which compels the research and development of non-toxic and biodegradable reagents such as polysaccharides. Therefore, three starch depressants for hexagonal pyrrhotite were used in this study. They include a paste starch with higher molecular weight (MW), a paste starch with lower molecular weight, and a crosslinked starch formed by mixing the lower MW paste starch and copper ions. We hypothesize that the presence of crosslinking additives such as copper provide a “driving” effect towards the gangue mineral. The performance of depressants was investigated in single and binary mineral systems. For single minerals, all depressants impacted hexagonal pyrrhotite and pentlandite flotation recovery. For the binary mineral systems, the higher MW paste starch and crosslinked starch showed an improved Ni separation efficiency of 90.5% and 85.6%, respectively, at an intermediate PIBX dosage (9.66x10⁻⁶ M) compared to the lower MW paste starch (58.6%), demonstrating a certain selectivity. The choice of the most suitable starch depressant proved to be complex since both minerals were able to chemically interact with the starch depressants as verified via X-ray photoelectron spectroscopy (XPS). Hydroxyl groups present on the α-D-glucose units bound with surface metal (Fe and/or Ni) hydroxylate species while the crosslinked starch also interacts with the mineral surfaces by electrostatic attraction. These findings will contribute to the advancement of knowledge related to the use of polysaccharides as depressants for complex sulfide mineral systems.
Article
Starch gelatinization under microscopy shows a continuous change of granule swelling and birefringence number whereas is yet inspected by eyes with inevitable subjective errors. In this study, a novel microscopy observation was developed for characterizing starch swelling capacity (SC) and its degree of gelatinization (DG) through a computer graphic analysis combined with deep learning techniques. SC and DG present a similar trend which was not seen a significant change before 60 °C followed a dramatical increase within 60–70 °C. The significant increase of DG was slower than SC, so that there were still high ungelatinized degrees at 68 °C when granules had disintegrated completely. In the case, the birefringence of small granules was efficiently identified and a high accuracy of 95% was achieved by using improved Starch-SSD. It may provide a fast and high throughput characterization of gelatinization merely based on a machine learning analysis of the photographical evidence.
Article
Slow digestion starch (SDS) and resistant starch (RS) are usually used as additives or raw materials in food processing due to their low glycemic index (GI) and low digestibility, imbuing products with physiological function, such as hypoglycemic activity and anti-obesity. But due to the lack of standardization of experimental methods, great differences have been reported in the results of various studies, which mean that the reference of experimental consequences is decreased, and the development of starch processing technology is then hindered. Moreover, the detailed structural changes in starch during different types of modifications are of necessity to be explored. In this paper, the structural characteristics and physiological functions of functional starch (SDS and RS) were reviewed, the physical, enzymatic, chemical and physicochemical preparation methods of functional starch from different plant sources were compared as well. In addition, the applications of functional starch in food industry were summarized, which were expected to provide the references for optimizing starch modification efficiency and functional food development.
Article
Background There has been a growing interest in consumers around the world in adopting a more plant-based diet for health, sustainability, and ethical reasons. Many commercially successful products have already been developed, including plant-based meat and milk analogs. However, the production of plant-based cheese analogs that consumers find desirable and acceptable has proved extremely challenging. This is mainly due to the compositional and structural complexity of real cheese products, which is difficult to mimic using plant-derived ingredients. Scope and approach In this review article, we start by providing a brief overview of the production and properties of real dairy cheese. We then describe the plant-based ingredients and processing operations that can be used to assemble cheese analogs that mimic the composition, structure, physicochemical properties, sensory, and nutritional attributes of real cheese. We also consider in this review the potential impact of switching from animal-based to plant-based cheese on the environment and human health. Key findings and conclusions Plant-based cheeses can be produced from plant proteins obtained using fractionation or tissue disruption routes. These products are typically complex colloidal dispersions consisting of lipid droplets embedded within a viscoelastic polysaccharide and/or protein network. Plant-based cheeses are more environmentally sustainable and better for animal welfare than their regular counterparts. More research is needed to identify appropriate ingredients and processing methods, including understanding the changes in texture and flavor as well as creating appropriate melting behaviors. Moreover, further research is required to improve the nutritional profile and test the health effects of plant-based cheeses.
Article
s Plant-based hydrogels have great potential for applications, motivated by favorable sustainability profile as compared to other sources. They can be engineered to exhibit tailor-made textural structures and functional properties via tuning interrelated factors. The interrelationships between hydrogel fabrication, constitutive nature, mechanical properties, and performance underlie the fundamental design rationale for applications in different disciplines. Herein, we comprehensively review the nature characteristics of network-building blocks (particularly legume proteins and starch) and gelation principles of plant-based hydrogels. Special highlights are focused on how these involved factors impact hydrogel formation, and in turn modulate its network structures and performance. We also propose some trends in advanced hydrogel designs which can inspire new applications and provide convenient anchoring points for enhanced functions in prospect.
Article
The role of amylase is often neglected in the separation of starch by protease despite the fact that it likely impacts the properties of starch. This study aimed to explore the effects of endogenous alpha-amylase on the pasting properties of starch during isolation using protease. A strategy is developed according to prevent the influence of alpha-amylase on starch pasting properties. Decreased pasting viscosity was observed in the presence of endogenous alpha-amylase while an increase in reducing sugar during incubation decrease viscosity due to starch degradation. The addition of acarbose effectively inhibits starch degradation due to endogenous alpha-amylase. However, acarbose does not appear to affect protease activity. Thus, a combination of protease and acarbose can effectively prevent interference from endogenous alpha-amylase without affecting the gelatinization properties of starch.
Article
Starch modification arises from the need to obtain starches with the desirable properties, being the physical modification techniques preferred over the chemical ones. Pulsed electric fields (PEF) can improve starch extraction and alter starch properties by decreasing the relative crystallinity, gelatinization temperatures and enthalpies, viscosity and pasting temperature. The lamellar repeating distance can be altered depending on the starch botanical origin. PEF can alter the digestible starch content, while maintaining the resistant one. Future research of the amylopectin structure may provide reasoning for these variations in starch digestibility behavior. The in-vitro human simulated digestion points to a decrease in digestibility.
Chapter
The extensive utilization of fossil-based, nonbiodegradable materials has caused serious environmental damages that have evidenced the need for their replacement by bio-based, environmentally friendly materials. Starch is a promising alternative in the field of bio-based materials for being naturally abundant and available, relatively cheap, and highly biodegradable. However, there are some challenges to be overcome for its use as a substitute for fossil-based polymers, such as poor mechanical properties, high vapor permeability due to its hydrophilic nature, and the tendency of undergoing retrogradation. Improvement of starch-based materials can be accomplished by physical, chemical, and biological strategies. This chapter presents an overview of starch properties, extraction and processing methods, and strategies for starch-based materials development and applications. A patent survey on starch-based materials is also presented, especially focusing on starch-based polymer blending and compositing, foaming, and nanocomposites.
Chapter
The starch-based hydrogels are one of the significant materials that have contributed greatly to industry, technology, and medicine. In this chapter, various aspects of starch-based hydrogels have been discussed. The chapter critically summarized the major outcomes of starch-based hydrogels that include introduction of starch-based hydrogel materials, various synthetic approaches such as one-step synthesis, two-step synthesis, and radiation-initiated graft copolymerization, self-assembly-driven formation, different types of starch-based polymer blends and their applications in diversified fields.
Chapter
Starch, a natural polymer is an important renewable resource which has attracted significant interest for application in various fields including industrial applications. Native starch as well as modified starch is being increasingly used in many technologies and processes owing to their versatility, biodegradability, cost effectiveness, easy usage and availability. These characteristics of starch and its derivatives result a growing interest towards their application in advanced functional materials including typical consumer polymer applications. This book chapter mainly focuses on the properties of starch and its derivatives along with their traditional as well as trending applications in varied areas including food applications, pharmaceutical and cosmetic industrial applications, advanced functional material applications and tissue engineering applications.
Chapter
Full-text available
The technological importance of the glass transition in amorphous polymers and the characteristic temperature at which it occurs (the glass transition temperature, Tg) is well known as a key aspect of synthetic polymer science (Ferry, 1980; Rowland, 1980; Sears and Darby, 1982). Eisenberg (1984) has stated that “the glass transition is perhaps the most important single parameter which one needs to know before one can decide on the application of the many noncrystalline [synthetic] polymers that are now available.” Especially in the last several years, a growing number of food scientists have followed the compelling lead of the synthetic polymers field by increasingly recognizing the practical significance of the glass transition as a physicochemical event that can govern food processing, product properties, quality, and stability (Slade, 1984; Slade and Levine, 1984a, 1984b, 1987a, 1987b, 1988a-e; Franks, 1985a, 1985b; Blanshard, 1986, 1987, 1988; Levine and Slade, 1986, 1987, 1988a-f; Blanshard and Franks, 1987; Schenz, 1987; Slade et al., 1988; Simatos and Karel, 1988; Karel and Langer, 1988; Marsh and Blanshard, 1988).
Article
Full-text available
The microstructure of food matrixes, and specifically that of wheat-flour dough, determines mechanical behavior. Consequently, the analysis of such microstructure is both necessary and useful for understanding the physico-chemical and mechanical alterations during the production of cereal-based products such as breads. Confocal laser scanning microscopy (CLSM) is an established tool for the investigation of these matrix properties due to its methodical advantages such as easy preparation and handling, and the high depth resolution due to the optical sectioning of probes. This review focuses on the microstructure of wheat- flour dough from a mechanical and visual point of view. It provides an overview of the dependencies between the visibly detectable microstructural elements achieved by CLSM and the physical determined rheological properties. Current findings in this field, especially on numerical microstructure features, are described and discussed, and possibilities for enhancing the analytical methodology are presented.
Article
Full-text available
Starch from normal (CDC McGwire, SR 93102), waxy (CDC Fibar, HB 364), and High amylose (SB 94897, SB 94893) hull-less barley cultivars was isolated and its structure, morphology, and properties were studied before and after one-step annealing (50°C for 72h at a moisture content of 75%). The amylopectin structure of all starches was nearly identical. The X-ray pattern of CDC Fibar, HB 364, and CDC McGwire starches was of the ‘A’-type. Whereas, SR 93102, SB 94897, and SB 94893 starches exhibited a mixed ‘A+B’-type pattern. The relative crystallinity (RC), swelling factor (SF), amylose leaching (AML), gelatinization temperature range (GTR), enthalpy of gelatinization (ΔH), amylose–lipid complex melting temperature (TpCX) and the enthalpy of melting of the amylose–lipid complex (ΔHCX) ranged from, 37.0% to 44.3%, 41.0–54.2% (at 90°C), 4.0–31.0% (at 90°C), 11.4–22.5°C, 6.0–13.0J/g, 84.9–89.1°C and 0.4–1.8J/g, respectively. The RC of CDC Fibar, HB 364, SR 93102 and CDC McGwire starches increased on annealing. Whereas, it remained unchanged in SB 94897 and SB 94893 starches. The ‘A’-type X-ray pattern of CDC Fibar, HB 364, and CDC McGwire starches remained unchanged on annealing. However, the ‘A+B’-type X-ray pattern of SR 93102, SB 94897 and SB 94893 starches resembled more closely the ‘A’-type pattern on annealing. In all starches, the X-ray intensity of the V-amylose–lipid complex peak increased on annealing. Annealing increased the gelatinization transition temperatures and decreased the GTR in all starches. The ΔH of SB 94893 starch increased on annealing, whereas it remained unchanged in the other starches. TpCX of SR 93102 and SB 94897 remained unchanged on annealing, whereas TpCX of CDC McGwire increased slightly. ΔHCX of native and annealed CDC McGwire, SR 93102 and SB 94897 were similar. TpCX and ΔHCX were not detectable in annealed SB 94893 starch. In all starches, SF decreased on annealing. Annealing decreased AML in SR 93102, SB 94897 and SB 94893 starches in the temperature range of 50–90°C, but increased AML in HB 364 and CDC McGwire starches at higher temperatures. The effect of annealing on acid hydrolysis was marginal.
Article
Full-text available
A novel staining procedure has been developed to visualize the gluten-starch matrix in wheat flour dough. Dough samples mixed to the final stage were stained with 26 fluorescent reagents, and each stained sample was observed with three sets of fluorescence filters (blue, green, and red). Of all the combinations of reagents and filters, the combination of acid magenta and the blue fluorescent filter set was the most effective in distinguishing starch granules from gluten network structure. Its effectiveness was further demonstrated with gluten and starch granule samples, in which the contrast was clearer when observed with the blue fluorescent filter set than without any fluorescent filter. Visualizing the gluten-starch matrix in dough samples at four mixing stages with the same procedure resulted in clear identification of the changes in gluten network structure because of the differences in mixing stages. The same procedure also enabled us to distinguish starch from gluten in white salted noodles, baked cookies, and flour particles. The proposed procedure is quicker, simpler, and has a lower risk of altering the sample than other conventional ones, and it is expected to become a useful tool in cereal studies.
Article
Full-text available
Recent developments in methods and instrumentation have contributed to major advances in our understanding of the fine structure of amylose and amylopectin. The structure of the starch granule slowly unravels with new insight into key structural features. Following a brief presentation of the structural features common to all starches, the most recent findings for the structure of amylose and amylopectin are reported. The organization of different types of chains in amylopectin is discussed with a critical review of the ‘cluster’ model leading to the presentation of alternative models. The locations of molecular components in the starch granule are described according to a progress structural order. The description of the crystalline components is followed by a presentation of their supramolecular arrangements. The crystalline components comprise platelet nanocrystals which have already been identified and characterized, and other less well characterized ‘blocklet components’. The location and state of amylose within the granule is also presented. This comprehensive review aims at distinguishing between those structural features that have received widespread acceptance and those that are still under debate, with the ambition of being educational and to provide stimulation for further fundamental investigation into the starch granule as a macromolecular assembly.
Article
Full-text available
Granular, cold water soluble (GCWS) wheat and corn starch can be prepared by heating in aqueous alcohol and evaporating the solvents. GCWS starch was characterized by light and electron microscopy, x-ray diffraction, HPLC, enzymic hydrolysis, the Brabender Amylograph, and differential scanning calorimetry. Charakterisierung von körniger, kaltwasserlöslicher Stärke. Körnige, kaltwasserlösliche Weizen- und Maisstärke (GCWS) kann durch Erhitzen in wäßrigem Alkohol und Verdampfen des Lösungsmittels erhalten werden. GCWS-Stärke wurde durch Licht- und Elektronenmikroskop, Röntgenbeugung, HPLC, enzymatische Hydrolyse, den Brabender-Amylographen und Differential-Raster-Kalorimetrie charakterisiert.
Article
solution to the use of starch in products. The determination of molecular characteristics with asymmetrical flow field-flow fractionation is described, and the behavior of starch in binary solutions is discussed. The organization of starch in granules and the changes in organization during gelatinization and retrogradation are then described. The role of starch retrogradation in bread staling is described in some detail, and the influence of water mobility and distribution is discussed in relation to amylopectin retrogradation. Finally, the use of starch as emulsifier is described. Hydrophobically modified starch is one possibility for emulsion stabilization; also, the starch granule as such can be used to stabilize emulsions (so-called Pickering emulsions).
Article
Using a combination of techniques, small- and wide-angle X-ray scattering, differential scanning calorimetry and small-angle neutron scattering, it has been possible to follow the stages that occur during gelatinisation in excess water for a range of starches. It is found that water enters the amorphous growth rings first, and that this is where all the swelling is concentrated. The periodicity of the semicrystalline stack remained unchanged as long as the crystallites can still be identified. As the temperature is raised further through the gelatinisation endotherm, the crystallites become destabilised and the crystallisation index drops to zero, rather beyond the end of the endotherm revealed by DSC.
Article
Starch is the most important source of human food energy and also an important polymer for biofuels, processed food, and pharmaceutical industries. Precise determination of structural and functional properties of starch has been an outstanding factor for the improvement of dissolution and degradation processes, which are important procedures for commercial applications. Distinct separation techniques coupled with multiple detection methods such as Size Exclusion Chromatography (SEC), Field Flow fractionation (FFF), Analytical Ultracentrifugation, and Hydrodynamic Chromatography have provided powerful information about starch conformation. In the present review, we describe the usefulness and limitations of different separation methods particularly SEC and FFF, which are currently widely used.
Article
Starch retrogradation is the main cause of quality deterioration in starch-containing foods during storage. The current work investigates the effect of different cations on the retrogradation of corn starch and the potential of reducing starch retrogradation with the aim of preparing products with an extended shelf life. To gelatinize the starch, starch–water suspensions containing various chloride salts (LiCl, NaCl, KCl, MgCl2, CaCl2, and NH4Cl) were heated in a DSC, stored up to 504 h at 8°C, and reheated again. Analysis of gelatinization behavior for each salt type indicates a relationship to the aW-value of the starch–water system. The degree of re-crystallization was calculated using the Avrami equation, and indicates that the starch re-crystallization rate (k) is significantly (p < 0.01) reduced with the addition of a cation, unlike the reference (starch–water systems without salt). Further, bivalent cations such as Ca2+, Mg2+ decreased the starch re-crystallization rate (k) more than univalent cations (Li+, NHmath image, Na+, and K+). This result may be based on the theory that high cations with higher charge densities show greater hydration, and, therefore, lower aW-values, than cations with lower charge densities. The results illustrate important results for predicting starch quality change when using sodium replacements.
Article
In this paper the influence of water content on the rheological, microstructural and sensorial properties of durum wheat bread was evaluated. In order to evaluate bread quality, oscillation measurements, stress relaxation test and creep–recovery measurements were performed on dough samples, whereas tomographic and sensorial analyses were performed on baked bread samples. Results of the rheological analysis highlighted that both the storage and loss moduli (G′, G″) showed a descending trend with the increase of the water content. This is also confirmed by stress relaxation tests. Creep–recovery tests for strong doughs (with low water content), recorded greater resistance to deformation, therefore a smaller creep strain than the softer doughs. These results were reflected in the microstructural properties of the bread; an increase in water content caused an increase in the percentage volume of pores. Regarding the sensorial properties, the overall acceptability of the investigated bread samples was low for both the lowest and the highest water contents, and this was due primarily to the compact crumb with small bubbles and high crust firmness for the former and to the loaf volume collapsed with irregular distribution of very large bubbles for the latter. Therefore, the bread samples with intermediate water content were preferred by the panelists.
Article
The effect and the correlation of water addition to flour on the microstructure and viscoelastic properties of wheat flour dough were investigated using confocal laser scanning microscopy and a spectrum of rheological methods. Dough with water addition in the range of 52.5–70.0 g water 100 g−1 flour was investigated using a stickiness test, uniaxial elongation test, and fundamental rheology like small amplitude oscillatory shear measurement and a creep recovery test. A method for quantifying the microstructure of dough protein gained by CLSM was established with image processing and analysis. The complex shear modulus decreased rapidly with water addition due to the plasticization effect of water molecules and increased mobility in the continuous phases. Elastic behavior, determined as loss factor tan δ and relative elastic part Jel decreased. Rheological tests showed high linear correlations with each other (r of |0.66|–|0.98|). Image analysis measurements (average size, area fraction, perimeter, circularity, and fractal dimension) showed high linear correlations (r of |0.66|–|0.85|) with water addition and rheological attributes like the complex shear modulus (r = 0.85) and Jel (r = 0.86). CLSM in combination with image processing and analyzing has proven to be an applicable and powerful tool for examining and quantifying dough protein microstructure. Hence, it was possible to prove the dependency of rheology on the microstructure of dough.
Article
The effect of sucrose on the physical properties of pound cake and batter with a total replacement by polydextrose was studied. The aim of this work was to replace sucrose in high-calorie-baked-products like pound cake, while preserving their typical high volume and soft textural characteristics. Rheological tests for analyzing the structural changes during shear stress as well as the texture parameters like firmness and adhesive force of batter were measured.Batter analysis revealed differences between the stability under shear stress as well as in texture when replacing sucrose by polydextrose, which resulted in a less stabile batter due to the interfacial behavior of the polydextrose and the batter components. In the case of the baked pound cake, polydextrose gave a similar effect on all the textural and crumb grain features. Significant correlations between batter- and cake-volume were found (rsuc. = 0.88; rpoly. = 0.96). Similar to a total sucrose reduction, the decrease of polydextrose resulted in a significant increase in the pores average sizes (rsuc. = 0.97; rpoly. = 0.95), which are typical for an irregular crumb. Staling was evaluated over an 18 day period and the polydextrose containing cakes showed similar behavior to the control products containing sucrose.In summary it was possible to replace sucrose with the polydextrose substitute, which allowed a significant reduction in calories (~ 10%), and at the same time showing similar quality characteristics to the sugar containing control.
Article
Starch gelatinization kinetics governs rice cooking behaviour (cooking time and texture). Starch gelatinization however occurs unevenly in the cooking grain. The aim of this study was to investigate the dynamics of starch gelatinization topography in rice kernels cooked in excess water at two temperatures: 75 °C and 95 °C, for times ranging from 5 to 30 min. Gelatinization front position was assessed over time on 40 μm cross sections using four different tracking methods: directly or after iodine staining using a microscope or a stereomicroscope under normal or polarized light. The four methods gave similar results and the obtained kinetics can be used to model starch gelatinization during grain cooking.In parallel, changes in the structure of the peripheral area of cooked grains were investigated on 3 μm cross sections under the same cooking conditions. Microscopic observations by auto fluorescence and after iodine staining revealed dynamic peripheral cell disruption at the same time as starch gelatinization, which may have a major impact on starch leaching and hence on the textural properties of the cooked grain.
Article
Starch-rich raw materials are widely used in the food industry. Their functionality and end-use applications are markedly influenced by starch characteristics. Starches with varying amylose (AM) and amylopectin (AP) content are of particular interest due to their ability to influence and modify the texture, quality and stability of starch-based food products. The present study shows the influence of the AM/AP content on physicochemical and morphological properties of a range of starches (Maize = 3%, 23%, 71%; Potato = 2%, 21%; Wheat = 28; Barley = 3%, 25% AM content w/w of starch).Starches have been analyzed in terms of their chemical composition, water retention capacity, morphological characteristics, and pasting/thermal properties. The changes in starch granule morphology during gelatinization were monitored by confocal laser scanning microscopy (CLSM). The different analysis revealed that waxy-starches (AP>90%) had a high water retention capacity (1.2–1.5 times higher) and developed higher paste viscosities (up to 40% for maize; 43% for barley). The swollen granules were highly susceptible to mechanical breakdown and solubilized faster. Higher AM contents showed inhibition of an extensive granule swelling and lowered the paste viscosity. The exceptional integrity of the high-AM starch even prevented its gelatinization at atmospheric pressure. Significant differences in physicochemical and morphological properties between the starches from regular, high-AM and waxy strains have become evident, no direct relationship between the AM/AP contents and the internal growth ring structures of the starch granules could be identified by CLSM. The waxy starches had a higher gelatinization temperature (up to 2 °C) and enthalpy (up to 20%), which indicates a higher crystalline and molecular order.
Article
Pea, potato, wheat, and rice starches were annealed for 24 hr. Differ- ential scanning calorimetry data were collected; pasting characteristics were determined using the Brabender Viscoamylograph and the Newport Scientific Rapid Visco-Analyser (RVA); and amylose leaching during heating in the viscoamylograph was examined. Differential scanning calorimetry data showed an increased gelatinization temperature and enthalpy, and a narrower gelatinization temperature range for all starches. Viscoamylograph viscosity curves showed that annealing resulted in an increased peak viscosity (except for potato starch), and an increased viscosity upon cooling. The amount of amylose leached from the granules was not linked to viscosity changes. Less amylose was leached from the granules of annealed pea and potato starches. The amount of solubilized amylose was practically unchanged (slightly Annealing of granular starches involves incubation in excess water, for a certain period of time, at a temperature above the glass transition temperature but below the gelatinization temperature. The first observations of the effects of annealing on starch were probably reported by Gough and Pybus (1971), although those authors did not use the term. Using Kofler hot-stage microscopy, they observed both an increase of the gelatinization temperature and a decrease of the gelatinization temperature range as a result ABSTRACT
Article
The object of this research was to study the real time percent humidity of the air and consequently to analyze this humidity influences on bread rolls. An industrial baking process was visualised by the use of a high-temperature humidity sensor to measure the level of percent humidity of the air (V% H2O) in relation to the different H2O-steam amounts (SA). In this study H2O-SA from 0 to 3.256L(H2O)m−3 of the oven volume were used. After steaming the results of gas moisture without product (GMWoP) showed a higher maximum (approx. 5%) of the percent humidity of the air than the gas moisture with product (GMWP). The trials reveal that the presence of products (bread rolls) is a factor in attaining an increase in the percent humidity of the air which influences product quality. Baking with adequate percent humidity of the air bread roll volume increased by 20% compared to trials without steam. New methods were used to quantify product parameters like crust thickness, compression-force and crispness and to find out correlations with the area under the GMWP curve (auc). Strongest correlations with auc GMWP were found for mean and maximum compression-force. Furthermore, it was shown that the increase in crust thickness, lightness and colour change is mutually dependent on an increase change in the total GMWP.
Article
A review with 267 references. Use of starch–hydrocolloid combinations is widespread, particularly in the food processing industry. Many studies have been conducted with a goal of understanding why the addition of a small amount of a hydrocolloid influences the properties of a starch-based paste, gel, or food product. Multiple variables are encountered in the research reports, including the use of different types of starches and hydrocolloids and different methods of preparation and evaluation of composite pastes and gels. Most commonly, a starch–hydrocolloid composite paste and/or gel exhibited (as compared to the starch alone paste and/or gel) increases in peak and final viscosities, short-term retrogradation, and gel strength and decreases in the temperature of the initial rapid viscosity increase, granule swelling, starch polymer molecule leaching from swollen granules, and long-term retrogradation; but opposite effects have also been observed. Most evidence seems to point towards the following mechanisms: hydrocolloid molecule interaction with leached starch polymer molecules—in some cases increasing network formation and in other cases decreasing or weakening the network formed by starch polymer molecules, changes in starch granule swelling (either positive or negative changes), swollen granule association via depletion flocculation, and phase separation between amylose, amylopectin, and hydrocolloid molecules in the continuous phase. The overall conclusion is that, because of the complexity of the variety of systems, several mechanisms are likely to be operating and the proportions of competing mechanisms likely vary with different specific hydrocolloids, different starches, and different methods of preparation of composite pastes and gels.
Article
In order to produce quick-boiling noodles, we made partially pre-gelatinized wheat flour dough by the microwave heating method. A cylindrical-shaped piece of wheat flour dough containing 3% NaCl was heated by 117W microwave oven operating at 2450MHz. The sample dough was intermittently heated to allow sufficient gelatinization of the starch granules of the dough. The resultant changes in the internal temperature profiles of the sample dough were measured and compared with numerical prediction, which is the two-dimensional heat conductive equation with a term for internal heat generation based on Lambert’s law. In order to calculate the internal heat generation during microwave heating, we measured the dielectric properties of wheat flour dough at 2450MHz from 10 to 70°C by the open-ended coaxial probe method. The calculated temperature history could describe the feature of the experimental one during intermittently microwave heating. Furthermore, the progress of starch gelatinization according to the heat transfer in the sample dough was predicted by the Runge–Kutta gel method. A tendency that the total gelatinization degree increased slowly during the microwave intermittent heating was obtained in the calculated result.
Article
Confocal fluorescent microscopy was used to classify the types of damage in native and ball milled potato starch granules on the basis of their response on hydration. Damage to individual granules at room temperature was assessed using the integrity of the maltese cross and with two fluorophores, congo red and acridine orange. A variety of types of damage were found, ranging from granules that appeared physically intact with localised congo red fluorescence and a corresponding deficit in the maltese cross, to granules that had ‘exploded’, as hydration of the core ruptured the granule, leaving the outer layers of the granule split but ostensibly intact. Also found were granules with obvious fractures and apparently intact granules with fluorescent areas which sometimes exuded a puff of fluorescing material. When hydrated at room temperature the interior of granules sometimes forms a gelatinous mass while the exterior of the granules remained virtually unaffected. The differentiation of the outer layers of the potato starch granule from the inner layers suggests a macroscopic model of granule structure comprising an outer layer, that is resistant to both damage and gelation, covering a less resistant interior.
Article
Native, and one- and two-step annealed wheat, pea and potato starches were subjected to hydrolysis with pancreatin (1.34 nKat/mg starch, 37 °C, pH 6.0). While annealing increases enzyme resistance for wheat, pea and potato starches in the first (rapid) phase of hydrolysis, it increases the extent of degradation in the second (slower) phase for wheat and pea starches. Annealed potato starches, however, are still more resistant than native potato starch in the second phase of hydrolysis. Environmental scanning electron microscopy shows that enzymic degradation of wheat starch granules does not proceed uniformly throughout the granule population. Pancreatin action does not affect differential scanning calorimetry (DSC) gelatinisation characteristics of all studied native and of annealed potato starches. Although enzymic hydrolysis has no great effect on the DSC gelatinisation behaviour of native starches, partial enzymic solubilisation of the granules enhances the effects of annealing. After 2 and 120 h of solubilisation, DSC thermograms of annealed wheat and pea starches show somewhat broader peaks with lower enthalpies than those of the corresponding unhydrolysed starches. 13C CP/MAS NMR data of extensively (46%) degraded and undegraded native wheat starch granules show no change in double helix content, whereas after 57% solubilisation of one-step annealed wheat starch, a decrease in the proportion of double helices is observed. The 13C CP/MAS NMR signal at 31 ppm increases by a factor 2.0 for 46% solubilised native wheat starch, and by a factor 2.3 for 57% solubilised annealed wheat starch, indicating resistance of amylose-lipid complexes to pancreatin hydrolysis. Dissociation enthalpies, however, are higher than can be predicted from a concentration of complexes. The enthalpy of dissociation of amylose-lipid complexes, after enzymic hydrolysis, increases more for annealed than for native wheat starch. All the above suggest that, during annealing, molecular changes occur that have an impact on pancreatin hydrolysis.
Article
The thermal properties of water-insoluble amylose-stearic acid (18:0) complexes prepared under various conditions were studied by differential scanning calorimetry (DSC). Complexes were studied normally at a concentration of 5% in water at pH ∼7. Type I complexes formed at ≤ 60°C had dissociation temperatures (Tm) in the range 96–104°C. Type IIa polymorphs formed at ≥ 90°C had Tm = 114–121°C. Various ratios of types I and IIa were formed at 80°C depending on the duration of heating, but no intermediate form was detected. Annealing of the type IIa complex at 105°C and at 115°C gave rise to increasing proportions of type IIb polymorphs with Tm = 121–125°C and dissociation enthalpies of 32–34 J/g of amylose, depending on the temperature and time of annealing. Conversion into the higher polymorphs was retarded at a higher concentration (10%) of the complex under identical conditions, and was delayed at pH ∼ 4.7. The dissociation temperatures of amylose complexes with the cis-unsaturated fatty acids oleic (18:1), linoleic (18:2), and linolenic (18:3) also depended on the temperature of formation, and three distinct types were obtained (I, IIa, and IIb). Significant decreases in the Tm of the three polymorphs were observed for each double bond in the fatty acid guest molecule. When type I and type II complexes were made using various proportions of 18:0 and 18:2, mixed acid complexes were obtained with Tm values intermediate between those of the monoacid complexes. The origin of the endothermic transitions on heating the three types of complexes is discussed.
Article
Effects of guar (GG) and xanthan (XG) gums (0.35–1.0% w/w) on pasting and rheological properties of waxy corn starch (WCS) (6.0% w/w) were studied. GG had a higher molecular weight but lower intrinsic viscosity than did XG, indicating that the GG chain was more flexible. RVA results indicated that viscosity and pasting temperature of the WCS dispersion during pasting increased with increasing GG or XG concentration. Dynamic viscoelasticity measurements indicated that the WCS/XG mixed pastes exhibited slightly superior viscoelastic properties to the WCS/GG pastes as evidenced by their higher G′ and lower tanδ values. Flow tests showed that the WCS/GG pastes exhibited mainly thixotropic hysteresis loops during a full shear cycle, whereas the WCS/XG pastes showed much less thixotropic and eventually became antithixotropic at high XG concentrations. In-shear structural recovery of the pastes increased more with increasing XG concentrations than did pastes with increasing GG concentrations. The differences in molecular characteristics of the GG and XG chains are hypothesized to be responsible for the above mentioned effects.
Article
Differential scanning calorimetry (DSC) has been used to study gelatinisation phenomena of sago starch. Two endothermic transitions were observed for starch heated in the presence of a limited amount of water (starch/water=37–50%w/w). These transitions appear to be due to co-operative effects of water-mediated melting of starch crystallites, remaining crystallites and/or amylopectin crystallites. At a water content of 50%, evidence of M1 endotherm was observed and 85°C represents the effective Tm at the end of melting of native sago starch. The effect of starch concentration on the shape of these two endotherms was studied for sago starch. The experimental data were treated thermodynamically by applying equations describing phase transition of semi-crystalline polymers. The T0m value obtained by extrapolation to v1=0 was 390.6K for sago.
Article
Analysis of swelling power, water retention capacity, and degree of gelatinization of corn flour cooked in water with and without lime indicated, over a concentration range of 0-1% (w/v), that at low concentrations, lime increases swelling and digestibility of starch granules. Measurement of starch solubility revealed an increase in the amount of starch dissolved by lime cooking. Swelling, retention, and gelatinization exhibited maxima at or near 0.2% (w/v) lime, and then decreased as lime concentration increased. Hot-stage polarized light microscopy and differential scanning calorimetry of isolated starch revealed increasing gelatinization temperatures with increasing lime concentrations. It is hypothesized that the high pH of the system causes starch hydroxyl groups to ionize, thereby creating binding sites for Ca++/CaOH+ and producing Ca-starch crosslinks. It is also suggested that, at low lime levels (<0.4%, w/v), granule crystalline regions are disrupted and the granule matrix is stretched by exchange of protons for calcium ions: when the lime level surpasses 0.4% (w/v), the granule shell becomes stabilized by Ca++-starch interactions, producing stronger, more rigid granules.
Article
The effects of annealing on the complexing of added palmitic acid (PA) and on the physicochemical properties of starch were studied. Palmitic acid was used because of its predominance in starch lipids. Starches naturally low in lipids, including potato, tapioca, and waxy corn, were subjected to the PA treatment. Common corn starch, which is high in lipids, was also included for comparison. More PA was complexed by annealed starches than by native starches and the amount of bound PA was mainly influenced by the amylose content. The introduction of PA decreased the gelatinization temperature and increased the gelatinization range of both native and annealed potato and tapioca starches. Leaching of amylose was reduced by the annealing treatment and further decreased by adding PA. Annealing did not change the swelling power of the PA-complexed starches. A small portion of the added PA formed complexes with amylopectin and still remained in the Naegeli dextrins after 10 days of acid hydrolysis. The reorganization of starch molecules with starch granules from annealing strongly affected the amount of complexed PA and some physicochemical properties of the introduced starches.
Article
A relatively large volume of maize starch suspension (2.5–20% w/w solids) is heated to above its gelatinization temperature by two means: a microwave oven meant to provide a uniform global thermalization of the sample, and a conventional local electrical heater which, depending on agitation, yields different heating patterns on the sample. The progress of gelatinization is registered on-line by an electrical conductance technique. Contrary to what is observed in the conventionally heated samples, gelatinization is not completed in the microwave irradiated samples although the temperatures reached are as high as with conventional heating. This is attributed to poor mass transfer of water molecules during microwave irradiation as a result of the short processing period and the absence of mixing of water with starch components. The latter is in line with observations regarding the role of agitation in gelatinization under conventional heating.
Article
Scanning electron micrographs of the granules of 54 starches obtained from a wide variety of plant sources, consisting of roots and tubers, grains, maize, peas and beans, fruits and nuts, and small granule starches, are presented as a comparative study of their sizes and morphologies. All micrographs are presented at a magnification of 1500X with the addition of micrographs of 600X for the very large granules and micrographs of 10,000X for the very small granules. Untersuchungen zur Morphologie von Stärkekörnern mittels Raster-Elektronenmikroskopie. Anhand von Raster-Elektronenmikroskop-Aufnahmen werden vergleichende Untersuchungen zur Größe und Erscheinungsform von Stärkekörnern angestellt. Betrachtet werden 54 Stärketypen der unterschiedlichsten pflanzlichen Herkunft, darunter Wurzeln und Knollen, Getreide, Mais, Erbsen und Bohnen, Früchte und Nüsse sowie kleinkörnige Stärken. Alle Mikroskop-Aufnahmen stellen eine 1500-fache Vergrößerung dar; zusätzlich sind die sehr großen Körner in 600-facher und die sehr kleinen Körner in 10.000-facher Vergrößerung abgebildet.
Article
Cereal Chem. 79(3):349-353 Thermomechanical analysis (TMA) and differential scanning calori- metry (DSC) were used to investigate the thermal transitions of long-grain rice kernels. Three distinct thermomechanical transitions were identified as rice kernels were heated from 0 to 200°C. The identified transitions were a low temperature transition with onset at ≈45°C, an intermediate tem- perature transition at ≈80°C, and a high temperature transition at ≈180°C. Low temperature transition with onset from ≈60°C at 5% moisture content (MC) to 30°C at 20% MC was identified as the glass transition of the rice kernels. Intermediate temperature transition from 60 to 100°C, depending on MC, may be caused by rapid evaporation of moisture in the rice kernels. High temperature transition was associated with melting of the crystalline structure of rice starch. The temperatures of all three transitions decreased as MC increased, confirming that moisture acted as a plasticizer in rice kernels.