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Interpretation of mechanical spectra of carob fibre and oat wholemeal-enriched wheat dough using non-linear regression models
Abstract
Oscillation and creep shear tests were applied to test the effect of fibre-rich additions – carob fibre (0–5%) and black oat wholemeal (0–20%) – on the rheological properties of wheat flour dough. Interpretation of changes in the values of the storage modulus (G′) and loss modulus (G″) and the tangent of the phase angle (tan δ) in the function of oscillation frequency (f) was performed on the basis of proposed 3-parameter non-linear regression models. The results of creep measurements were analysed using the 6-parameter Burgers model. Increase in the share of the fibre-rich additions caused the G′(f) and G″(f) curves to shift towards higher values, and steeper slope and stronger bending of the shapes of the curves, while the tan δ(f) curve tended to shift towards lower values. The application of carob fibre and oat wholemeal at rates of 2% and 10%, respectively, caused that the ratio of viscous to elastic properties of wheat flour dough was the least dependent on the shear rate (f). The result of creep tests showed an increase in the instantaneous and retarded moduli of elasticity and the Newtonian viscosity of wheat flour dough with increase in the share of the additions.
... The viscoelastic behavior obtained through small amplitude oscillatory shear test which does not destroy the analyzed structure and gives valuable information about the structural modifications in dough system. In addition, static creep-recovery test used in dough rheology analysis allows predicting the bread loaf volume and dough behavior in stages such as fermentation or during oven spring (Miś 2011). The evaluation of GPF particle size and addition level effect on dough rheological behavior is essential in the development of new fiber-rich bakery products because it may influence the processability, extensibility, resistance to stretch, the gas-holding capacity of the dough, viscoelasticity, and, consequently, the quality of the baked bread. ...
... The excess dough was removed and vaseline was applied to the exposed edge of the sample to protect it from loss of moisture during testing. Prior to perform the frequency sweep, the limits of linear viscoelastic region (LVR) of the sample was determined based on the strain sweep experiments in which increasing strain was applied, from 0.01 to 1%, at constant oscillation frequency of 1 Hz, according to some indications (Miś 2011;Lazaridou et al. 2007). For oscillatory measurements, the 15 Pa stress was chosen in the LVR where dough samples exhibit a linear relationship between stress and strain. ...
... This solid elastic-like behavior of dough may be attributed to the repulsive forces between starch granules which are predominant and lack of binding agents (Sivaramakrishnan et al. 2004) in the composite flour dough samples analyzed. A similar trend was reported for various doughs formulation such as, glutenfree bread dough, fiber-rich dough, cookie doughs (Korus et al. 2012;Miś 2011;Pedersen et al. 2004). Both G′ and G″ moduli are influenced by the particle size, addition level and their interaction, indicating changes in the structural properties of dough. ...
The present study was undertaken to assess the effects generated by grape peels flour (GPF), as a source of dietary fibers, on the white wheat flour (WF) dough rheological behavior. Dynamic and empirical rheological measurements were carried out in order to study the viscoelasticity of GPF-enriched wheat flour-based dough matrices and to identify the main actions of GPF particle size (large, medium, and small) at replacement levels from 0% up to 9%. The water competition of GPF is explained by different water binding and gelling capacities, synergistic and/or antagonistic effects of GPF compounds on the major rheological properties. Power low and Burgers models were successfully fitted with the dynamic oscillatory and creep-recovery data being suitable to interpret viscoelastic behavior of dough. Composite flour dough with smaller particle size presented higher G′ and G″ values at addition level above 5% GPF, exhibiting higher viscous component with concomitantly higher peak viscosity. Creep-recovery tests for samples with small particle size at 5% addition level showed that the elasticity and the recoverable proportion was higher compared to the rest of GPF formulations and control sample. Significant correlations (p < 0.05) were found between several parameters determined by both dynamic and empirical rheological measurements which have essential roles in monitoring GPF-enriched wheat flour dough in a wide set of different kinds of samples. This information could be helpful to optimize the particle size and addition level of GPF that could be useful to produce GPF-enriched designed bread.
... Bread can be enriched with dietary fiber from various sources, namely wheat bran (Gómez, Jiménez, Ruiz, & Oliete, 2011), bglucans (Thondre & Henry, 2009), inulin (Morris & Morris, 2012), carob fiber and many other biopolymers (Mi s, 2011;Mi s, Grundas, Dziki, & Laskowski, 2012). Incorporation of fiber into wheat flour interacts directly with structural elements of the three dimensional gluten networks and disrupts the starchegluten matrix, and finally affects the rheological behavior of blended dough during mixing, fermentation, and baking. ...
... This is a true representation of viscoelastic network. Such behavior was earlier reported by various researchers for fiber enriched dough (Mi s, 2011;Singh et al., 2012). Both samples (control and fiber-enriched) showed an increase in G 0 and G 00 with increasing frequency from 0.1 to 10 Hz, with the elastic behavior dominating over viscous component throughout the frequency range. ...
The influence of water insoluble date fiber addition, to standard flour was studied through rheological tests at small and large deformations and at different levels of fiber incorporation (1e10 g/100 g). The added DF increased the water absorption of the dough. An increase in mixing time and stability were recorded upon addition of DF (5 g/100 g), and the extensibility decreased at similar condition. The elastic modulus, G 0 of the blended doughs increased with fiber concentration in the frequency range of 0.1e10 Hz, and the dough exhibited predominating solid-like behavior. The difference in microstructure between control and fiber incorporated dough samples were characterized by a plot of G 0 vs. G 00. During non-isothermal heating of doughs from 30 to 95 C at a heating rate of 2.5 C/min, the G 0 achieved its peak value (T G 0 max) at a temperature representing the peak gelatinization temperature (T p). Addition of DF did not significantly affect the T p of the dough. The dough gelatinization kinetics was described by two rate equations corresponding to upward and downward of gelatinization curve. The upward and downward curves fitted the first-order and the second-order reaction kinetics, respectively. The gelati-nization process activation energies ranged between 129 and 194 kJ mol À1 .
... Rye flour contains 4-7% of pentosans, which greatly contribute to the viscosity of the dough [19]. Mixtures 2A, 2B, 3A, and 3B had higher apparent viscosity values than respective mixtures 1A and 1B, and this may be due to a higher fiber content [20]. Doughs 2 and 3 contained carob flour, which is known to have high dietary fiber content with large proportion of galactomannans [21]. ...
... Doughs 2 and 3 contained carob flour, which is known to have high dietary fiber content with large proportion of galactomannans [21]. The effect of fibers on dough rheology is related to their increased water-binding capacity [20]. For this reason, water amount was adjusted for mixtures 2A, 2B, 3A, and 3B until the appropriate rheological properties of the material, suitable for their printing, were achieved. ...
In this study, we designed high fiber cookie recipe without using additives by means of extrusion-based 3D printing. We aimed to relate printing quality and cookie physical properties with dough rheology and dietary fiber content depending on the flour (oat, rye, rice, and carob flour) and fat type (olive oil or butter). The flour choice influenced all cookie quality parameters: baking loss, color, line height and width, and dietary fiber content. Results indicated that lower baking loss and better printing quality were obtained for cookie dough containing olive oil, which had higher viscosity and consistency coefficient compared with dough containing butter. Cookies with olive oil in which part of the oat flour was replaced with rye and carob flour were printed with high accuracy (≥98%), close to the ideal 3D shape. Overall, this study demonstrates the importance of selecting fat and particularly flour, as well as the extrusion rate on the quality and repeatability of 3D-printed cookies.
... An addition of TSF led to a decreased of JCo, except for the sample with 15% TSF which showed a slightly increase of the instantaneous compliance. This increase can be related to a slight firmness improvement of dough structure, in according to the result reported by Miś [64]. The highest change on JCo was found for the sample with 20% TSF, indicating a significantly (p < 0.05) decrease of the instantaneous elasticity. ...
... An addition of TSF led to a decreased of J Co , except for the sample with 15% TSF which showed a slightly increase of the instantaneous compliance. This increase can be related to a slight firmness improvement of dough structure, in according to the result reported by Miś [64]. The highest change on J Co was found for the sample with 20% TSF, indicating a significantly (p < 0.05) decrease of the instantaneous elasticity. ...
The rheological and microstructural aspects of the dough samples prepared from wheat flour and different levels of tomato seed flour (TSF) were investigated by rheology methods through the Mixolab device, dynamic rheology and epifluorescence light microscopy (EFLM). The Mixolab results indicated that replacing wheat flour with TSF increased dough development time, stability, and viscosity during the initial heating-cooling cycle and decreased alpha amylase activity. The dynamic rheological data showed that the storage modulus G’ and loss modulus G” increased with the level of TSF addition. Creep-recovery tests of the samples indicated that dough elastic recovery was in a high percentage after stress removal for all the samples in which TSF was incorporated in wheat flour. Using EFLM all the samples seemed homogeneous showing a compact dough matrix structure. The parameters measured with Mixolab during mixing were in agreement with the dynamic rheological data and in accordance with the EFLM structure images. These results are useful for bakery producers in order to develop new products in which tomato seed flour may be incorporated especially for wheat flours of a good quality for bread making and high wet gluten content. The addition of TSF may have a strength effect on the dough system and will increase the nutritional value of the bakery products.
... The dynamic rheological properties of dough samples formulated were assessed by performing a preliminary stress sweep test to identify the limits of the linear viscoelastic region (LVR) of the samples based on the strain sweep experiments in which increasing strain was applied, from 0.01 to 1%, at constant oscillation frequency of 1 Hz, according to some indications (Lazaridou, Duta, Papageorgiou, Belc, & Biliaderis, 2007;Mi s, 2011). The dough samples prepared without yeasts, at optimum farinograph water absorption by mixing until full dough development, were placed in a measuring system of a HAAKE MARS 40 rheometer (Thermo-HAAKE, Karlsruhe, Germany) with a parallel plate measuring system and rested for 5 min prior to testing to allow relaxation and stabilize temperature. ...
... The regression model from G 0 and G 00 showed that the dough with GPF enrichment exhibited more elastic behavior as compared with viscous behavior, the addition level having a highest contribution to the moduli variation. A similar trend was remarked for various fiber-enriched doughs formulation(Ahmed et al., 2013;Ghoshal & Mehta, 2019;Mironeasa et al., 2019;Mi s, 2011).The test for the precision of the quadratic model for tan δ indicates that the equation can be suitable to predict the loss tangent as a function of the formulation factors. The GPF type and level added in dough have a significant (p < .05) ...
The valorization of grape peels by‐product to supplement wheat bread has immense potential, particularly in refined wheat flour (RWF) to increase the dietary fibers. The main aims of this study were successful modeling of dough rheological properties using predictive models, investigating the effect of factors, grape peels flour (GPF) variety, level and particle size (PS) of GPF added in RWF on responses, and finally, optimizing the formulation with respect to dough rheological behavior. The rheological properties of grape peels–wheat composite flour formulated with GPF from two variety and increasing levels of GPF (0–9%) in the presence of different PS (large, L > 500 μm; medium, 200 μm > M < 500 μm, and small, S < 200 μm) of GPF was evaluated using farinograph, alveograph, and dynamic oscillation measurements. The artificial neural network models (R ² > .82) developed to predict dough rheological properties highlighted an improved estimation and predictive capabilities compared with response surface methodology models (R ² > .77). The multiobjective optimization approach allowed anticipation of the optimal value for each response in terms of dough rheological properties as function of GPF from white variety of small PS, which replaced RWF at level of 3.81%.
Practical applications
In the composite flour formulation to produce effectiveness and nutritive bread, optimizing dough rheology in relation to the formulation factors represents the actual need for the bread‐making industry. Dough behavior during mixing (water absorption, dough stability, dough development time, and degree of softening), alveograph parameters (dough tenacity, extensibility, and deformation energy), and dynamic rheological properties (elastic modulus, viscous modulus, loss tangent, and complex viscosity) are considered essential to optimization of grape peels–wheat composite flour formulation. The current study revealed the efficacy of modeling and optimization between response surface and artificial neural network techniques for the grape peels–wheat flour dough rheological properties. The information given from this study would help the industry to develop new bread‐making products with the desired particle size with optimum functional and nutritional properties.
... Bread can be enriched with dietary fiber from various sources, namely wheat bran (Gómez, Jiménez, Ruiz, & Oliete, 2011), bglucans (Thondre & Henry, 2009), inulin (Morris & Morris, 2012), carob fiber and many other biopolymers (Mi s, 2011;Mi s, Grundas, Dziki, & Laskowski, 2012). Incorporation of fiber into wheat flour interacts directly with structural elements of the three dimensional gluten networks and disrupts the starchegluten matrix, and finally affects the rheological behavior of blended dough during mixing, fermentation, and baking. ...
... This is a true representation of viscoelastic network. Such behavior was earlier reported by various researchers for fiber enriched dough (Mi s, 2011;Singh et al., 2012). Both samples (control and fiber-enriched) showed an increase in G 0 and G 00 with increasing frequency from 0.1 to 10 Hz, with the elastic behavior dominating over viscous component throughout the frequency range. ...
... Fig. 3(a) shows that the storage modulus (G′) of the model dough was much higher than the loss modulus (G″) for all samples. The doughs exhibited a typical response to a cross-linked polymer network with a predominantly solidlike behavior (G′ > G″) representing the viscoelastic network of the dough (Miś, 2011;Singh, Liu, & Vaughn, 2012). For all samples, initially, G′ increased and G″ decreased then a steady trend was maintained as time increased. ...
... This is a true representation of a viscoelastic network. Such behavior was earlier reported by various researchers for fiber-enriched dough(Miś, 2011). Both samples (control and fiber-enriched) showed an increase in G′ and G″ with increasing frequency from 0.1 to 10 Hz, with the elastic behavior dominating over viscous component throughout the frequency range. ...
Food waste utilization using technological innovations can aid in addressing food waste issues. Thus, this study aimed to develop functional biscuits enriched with apple, amla, and apple‐amla mix pomace (Industrial waste). The knowledge of the rheological properties of dough was considered during biscuit development. Besides, the effect of various combinations of apple, amla, and the mix pomace (5‐20% with 5% increment) on physical, textural, sensory, and microstructural characteristics of the functional biscuit was investigated. X‐ray micro‐computed tomography (X‐ray μCT) scanning coupled with image analysis was used for microstructural characterization. The textural attributes and color characteristics of the functional biscuits were significantly different compared to the control sample. The dough formulation (pomace) and variation in microstructure properties significantly affected the physical, textural, and sensory properties. Further, a remarkable reduction in the total volume (up to 25.4%) and total surface area of pores (up to 45.5%) of functional biscuit was noted. The volume fraction of solid‐phase showed an increasing trend as the composition of pomace rises and the porosity reduced drastically from 37.24 % in control sample to 17.48% in apple‐amla mix 20% sample. Three‐dimensional images of biscuits analyzed by an X‐ray μCT system also supported the quantitative results. The functional biscuit prepared by partial replacement of wheat flour by 10% amla pomace is best in dough rheology, microstructural, textural, and sensory attributes. In conclusion, amla, apple, and mixed pomace biscuits enhance the nutritional, functional, and overall characteristics of the sample. The results of this study aid in utilizing waste (pomace) of the amla and apple industry into a valuable dietary product.
... The physical properties of the dough were determined during development and mixing using a farinograph (model 810114, Brabender, Duisburg, Germany) equipped with a 50 g mixer bowl [32]. The parameters measured were the water absorption (WA) of the flour, dough development time (DT), dough stability time (ST), degree of dough softening and farinograph quality number [33]. ...
The objective of this study was to determine the grinding characteristics of wheat with a low moisture content. Two kinds of wheat—soft spelt wheat and hard Khorasan wheat—were dried at 45 °C to reduce the moisture content from 12% to 5% (wet basis). Air drying at 45 °C and storage in a climatic chamber (45 °C, 10% relative humidity) were the methods used for grain dehydration. The grinding process was carried out using a knife mill. After grinding, the particle size distribution, average particle size and grinding energy indices were determined. In addition, the dough mixing properties of wholemeal flour dough were studied using a farinograph. It was observed that decreasing the moisture content in wheat grains from 12% to 5% made the grinding process more effective. As a result, the average particle size of the ground material was decreased. This effect was found in both soft and hard wheat. Importantly, lowering the grain moisture led to about a twofold decrease in the required grinding energy. Moreover, the flour obtained from the dried grains showed higher water absorption and higher dough stability during mixing. However, the method of grain dehydration had little or no effect on the results of the grinding process or dough properties.
... In order to produce baked goods with added value, materials with a high fiber content are increasingly being used. High-fiber materials directly influence the dough rheology through the interaction of fiber-rich components with structural elements of the wheat dough during the dough mixing and stretching process [15]. The structural changes in the dough caused by the addition of fibers have a negative effect on the quality of the bread, especially on the loaf volume and crumb structure. ...
The rheological behavior of dough supplemented with sugar beet fibers (SBF) and carob (pod) flour (CF), as fiber-rich by-products of the agricultural industry, was investigated using the standard Brabender extensograph and the Kieffer micro method. The addition of CF (0–20%) and SBF (0–6%) to the wheat dough formulation increased resistance to extension to about 75% and 55% respectively, while the combined effect of CF and SBF addition increased the dough resistance by up to 100%. The extensibility of the dough decreased in almost identical ranges (up to 40%), while the combined effect of CF and SBF addition had a stronger influence on the decrease in dough extensibility (75%). The evaluation of the correlation between the extensographic and the Kieffer micro method showed a high compatibility with regard to the results of the dough extensibility (r = 0.89, p < 0.05), but did not confirm the agreement of the results obtained in the resistance measurements (r = 0.13, p < 0.05). Considering that the absolute correlation between the two rheological methods used was not confirmed in this study, it is clear that the precise and complete definition of rheological properties requires the use of other methods, not only empirical but also fundamental.
... Fibres contains reactive compounds, including phenolic acids, reducing agents, phytate (Noort 644 et al., 2010), that may easily affect the structure of gluten proteins , 645 and in consequence, the course of water redistribution between dough components (the 646 present results) as well as the rheological behaviour of the supplemented dough (Miś, 2011). The TGA measurements of weight loss at 600 °C were used to determine the 666 folding/aggregation power of the fibre supplements (Nawrocka et al. 2016), assuming that the 667 smaller the weight loss, the more compact and stronger gluten network is formed as a result of 668 gluten-fibre interactions. ...
The presented study is the first attempt to estimate the run of redistribution (migration) of water between individual components of model bread dough on the basis of changes in its consistency during mixing. To this end, farinograph mixing tests were performed with three types of dough: one-component gluten, two-component starch-gluten, and three-component starch-gluten-fibre dough. Wheat gluten and wheat starch as well as six commercial dietary fibre preparations were used as dough components. The fibres were applied as air-dried and pre-hydrated preparations in amounts: 0.03, 0.06, and 0.09.
The study results demonstrated that the migration of water from gluten to the fibre during mixing is promoted by both the enhanced fibre hydration capacity (physical redistribution) and the decrease in gluten hydration capacity induced by chemical interactions with fibre (chemical redistribution). Both types of redistribution caused significant decreases in the gluten hydration level; at the maximum fibre addition, they ranged from −0.05 (chokeberry fibre) to −0.22 (carrot fibre) and from −0.02 (carrot fibre) to −0.31 (oat fibre), for the physical and chemical redistribution, respectively. The dehydration of gluten resulted in deterioration of the mixing properties of the supplemented doughs. Most of the examined fibres exerted a destructive effect, i.e. they reduced the consistency of the dough even by half (oat and carob fibres). The fibre pre-hydration significantly mitigated this effect.
... Fig. 1a(II), (III) shows the tensile properties of different tea-enhanced doughs. Extensibility and maximum resistance (Rmax) are two important parameters in the tensile curve that determine dough energy (the area under the curve), which can reflect the ability to hold gas and the stability of the gluten network (Miś, 2011). As shown in Fig. 1a(II), the dough energies with green tea, soluble tea, and tea polyphenols were higher than the control sample, indicating that adding tea products enhanced gluten strength. ...
In this study, the improving effects of green tea powder, soluble tea, and tea polyphenols on the mixing and tensile qualities of dough and texture of tea-enriched noodles, as well as the physico-chemical and structural properties of gluten proteins were progressively investigated. Dough strength and noodle texture were significantly increased by all the three tea products. Tea polyphenols in particular presented the most effective improvement with highest dough stability, resistance, and noodle chewiness. SEM indicated that tea products all induced a more developed gluten network, and polyphenol noodle showed the most continuous and ordered structure. FT-IR and fluorescence spectrum indicated that tea polyphenols promoted an enhancement in α-helix structure and the hydrophobic interactions. Tea polyphenols induced the SH/SS interchange during processing and cooking, and enhanced the water-solids interaction in noodles. AFM results showed that polyphenols induced the polymerization of gluten protein molecular chains, with increased chain height and width.
... Comparing to oat whole meal, carob fiber caused an increase in rheological stability of dough during mixing [90]. The rheological tests of wheat flour also show that water absorption of dough can be increased by addition of carob fiber [91]. However, when carob fiber incorporation above 5 g/100 g, it would have a negative impact on extensibility and resistance of dough blend [5]. ...
Abstract Polysaccharides in carob fruit, including carob bean gum (also known as carob gum, locust bean gum) and carob fiber, are widely used in industries such as food, pharmaceuticals, paper, textile, oil well drilling and cosmetics. Carob bean gum is a galactomannan obtained from the seed endosperm of carob tree and the fiber is obtained by removing most of soluble carbohydrates in carob pulp by water extraction. Both the gum and fiber are beneficial to health for many diseases such as diabetes, bowel movements, heart disease and colon cancer. This article reviewed the composition, properties, food applications and health benefits of polysaccharides from carob fruit.
... Stress sweep tests in the range of strain from 0.01% to 1%, at constant oscillation frequency of 1 Hz were firstly conducted in order to define the linear viscoelasticity region, according to some indications (Miś, 2011;Lazaridou et al., 2007). Frequency sweep tests were performed in the range of 1 to 10 Hz at a strain value of 0.15% and temperature of 20.0 ± 0.1ºC to determine the storage modulus (G'), loss modulus (G''), loss tangent (tan d = G''/G') and complex modulus (G*). ...
The use of grape peels flour to improve the nutritional value of wheat flour bread has received considerable interest due to their high fibers content and bioactive compounds compared to white wheat flour. The aim of this study was to establish the optimal combination of grape peels particle size (PS) and flour replacement (FR) level with grape peel flour on the dynamic and empirical rheological properties of mix flour dough to develop innovative bakery products. The results obtained highlighted that the small PS resulted in increased Farinograph water absorption and Amylograph peak viscosity and decreased dough development time. The FR showed a significant (p < 0.05) effect on Rheofermentometer parameters. The dynamic moduli increased when increasing FR and decreasing PS, while the loss tangent decreased with FR increase. The white wheat flour with 3.80% small particle size of GPF was found to be the best formulation in order to achieve the desirable dough rheological properties.
... As illustrated in Figure 2B, creep and recovery curves of the dough samples corresponding to the designs 2 nd , 9 th , 14 th , which include a ratio 30:70 of einkorn, cranberry bean and potato flours and wheat flour, respectively, increased with the addition of both einkorn and potato flours but did not change with the addition of cranberry bean flour. Similar results have been found by other researchers, who found that the rheological properties of dough were affected by the addition of modified starch (Witczak et al., 2012), potato flour and β-glucan fibre (Mis, 2011). In the present study the viscoelastic properties of the dough samples were significantly affected by the presence of einkorn and potato flours due to the high dietary fibre content and the type of starch of these flours. ...
... As illustrated in Figure 2B, creep and recovery curves of the dough samples corresponding to the designs 2 nd , 9 th , 14 th , which include a ratio 30:70 of einkorn, cranberry bean and potato flours and wheat flour, respectively, increased with the addition of both einkorn and potato flours but did not change with the addition of cranberry bean flour. Similar results have been found by other researchers, who found that the rheological properties of dough were affected by the addition of modified starch (Witczak et al., 2012), potato flour and β-glucan fibre (Mis, 2011). In the present study the viscoelastic properties of the dough samples were significantly affected by the presence of einkorn and potato flours due to the high dietary fibre content and the type of starch of these flours. ...
The aim of this study was to analyse the effects of the addition of einkorn, cranberry bean and potato flours on the pasting characteristics of the mixture as well as the rheological properties of the dough formed. An experimental design using a simplex lattice mixture design was employed. The pasting parameters of the samples increased with the addition of cranberry bean and einkorn flours due to their high protein content. The water absorption capacities of the doughs were significantly affected by the polar nature (e.g. potato flour) and protein content (e.g. cranberry bean) of the flours. The creep-recovery properties of the doughs were analysed using the Burger model. Results showed that doughs enriched with potato flour exhibited weak elastic properties and behaved as a highly viscous material. Textural profile analysis of the doughs showed that their structure became firmer with addition of einkorn, cranberry bean and potato flours. The determination coefficient for the samples was higher than 0.70 in the simplex lattice mixture design.
... Fig. 3(a) shows that the storage modulus (G′) of the model dough was much higher than the loss modulus (G″) for all samples. The doughs exhibited a typical response to a cross-linked polymer network with a predominantly solidlike behavior (G′ > G″) representing the viscoelastic network of the dough (Miś, 2011;Singh, Liu, & Vaughn, 2012). For all samples, initially, G′ increased and G″ decreased then a steady trend was maintained as time increased. ...
... Moreover, carob fiber addition affects dough rheological properties (Wang and others 2001;Miś 2011;Miś and others 2012). At very low concentration, when mixed with starch and water at room temperature, it contributes to forming a very viscous solution (Dakia and others 2007). ...
The gluten-free market currently offers a range of products which can be safely consumed by patients affected by celiac disease. Nevertheless, challenges for optimal formulation remain on the way in terms of appreciable texture, flavor, and adequate nutritional characteristics. Within that framework, legumes have recently attracted attention among scientists as structure- and texture-forming agents, as source of nutrients and bioactive compounds, and as a low-glycemic-index ingredient. This work aims at providing an updated and comprehensive overview of the advantages and disadvantages in the use of legumes in gluten-free breadmaking. It also shows how legumes can contribute to tackling the main technological, nutritional, and organoleptic challenges. From this critical analysis, it emerged that viscoelastic properties of gluten-free bread batter can be enhanced by the use of carob germ, chickpea, lupin, and soybean. Gluten-free bread organoleptic acceptability can be improved by incorporating leguminous flours, such as carob, chickpea, lupin, and soybean. Moreover, a better nutritional quality of gluten-free bread can be obtained by the addition of chickpea and soybean. Gaps and needs in the use of legumes in gluten-free breadmaking emerged and were gathered together to have a sound basis for future studies. The technological and nutritional potential of sourdough should be more extensively exploited. Moreover, in vitro and in vivo studies should be prompted to understand the health benefits of bread formulated with legumes. A holistic approach, interfacing food science, nutrition, and health might help to have, on the market, products with improved sensory properties and nutritional profile.
... Dough rheology depends also on a wide variety of factors going from: quality, chemical composition and grinding parameters of wheat used for flour production to changes occuring in gluten structure during mixing [12,13], temperature, use of additives or fermentation process parameters [14][15][16]. Considering the facts presented above, the study of flour and dough rheological properties requires lately a special attention. ...
This work was aimed to determine the optimal storage conditions able to insure a sufficient flour maturity degree in order to improve its rheological and technological properties. To this purpose the Response Surface Methodology (RSM) was successfully employed. The effects of three different parameters (storage time, temperature and environmental humidity) on flour and dough rheological characteristics that were determined by farinograph analysis: water absorption, stability time and dough softening degree were studied. The RSM established optimum conditions for wheat flour maturation process were: storage temperature: 28°C, storage time: 21 days, environmental humidity: 68-70%. Under these conditions, for tested flour, the farinograph recordings revealed that water absorption increased with 0.5% comparing with initial product (after grinding process). In terms of dough stability time an augmentation of 20% was registered. Dough softening degree at 10 and 12 min were reduced with 30% and 27.66% respectively. These data provide information about the flour quality augmentation, Farinograph® quality number increase with 18%, and an improvement in flour technological characteristics. The mathematical model describes with accuracy the rheological properties evolution and generates viable optimized values in terms of storage conditions for a wheat flour type 650 (0.65% ash wt. %) which has a good or very good water absorption capacity (57-62%), an optimum development time (1.5 to 3 min.), a stability time in normal limits (6-15 min.) and a good consistency (35-80 BU) after grinding process.
... The calibration factor k was determined empirically in 200-s creep tests on dough prepared in an identical way as for the baking tests maintaining a constant dough temperature of 22°C and a constant shear stress of 25 Pa. The data obtained were described using the six-parameter Burger model (Miś 2011), and the measurement result of Newtonian viscosity η 0 was regarded as a calibration standard. ...
A measurement system was designed to study changes in the volume, pressure, and viscosity of dough leavened by baking powder during model baking. Analysis of the volume changes demonstrated two baking stages, i.e. dough expansion and crumb shrinking. Through the analysis of pressure and viscosity extremes, the expansion stage was divided into five phases: stress relaxation (R) characterised by a mild pressure decline; gluten matrix softening (S), during which the decrease in viscosity is accompanied by a gradual pressure rise contributing to substantial dough expansion (by ∼54 %); starch gelatinisation and protein aggregation (G) characterised by rapidly increasing viscosity; gas bubble opening (O) reflecting a rapid pressure reduction; and boiling of water in dough (B), which ends at initiation of crumb shrinking. The study showed that enrichment of the dough with carob fibre increased the contribution of phases S and O to dough expansion at the cost of phase G. A similar contribution of the expansion phases was reported for the Bombona cultivar, which exhibits the highest gluten content. In contrast, the Finezja and Katoda cultivars, which have a lower gluten level, were characterised by an approximately two-fold higher impact of phase G on the increase in dough expansion. The results indicated that the developed method for identification of baking expansion phases of leavened dough can be useful in baking characteristics of raw materials and bakery additives.
... However, the main problem of dietary fibre addition in baking is a significant reduction of bread quality, which is connected with changes in the structure of gluten proteins. There are a great number of reports confirming a negative effect of dietary fibre supplementation on the rheological properties of bread dough (Miś, 2011;Miś & Dziki, 2013;Peressini & Sensidoni, 2009), but only a few reports correspond to changes in structure of gluten proteins after addition of dietary fibre preparations (Sivam, Sun-Waterhouse, Perera, & Waterhouse, 2013;Sivam et al., 2012). The dietary fibres used in the present study were chosen because of their different sources of origin, and hence different chemical composition. ...
Over the years, the food technology has emerged in tandem with changes in dietary trends. New technologies have arisen that not only improve the flavor and shelf life of food goods, but also contain effective additives that are same for customers’ health and provide nutraceutical benefits. As a result, the adoption of natural alternatives to replace synthetic additives is increasing in ongoing research. Biosurfactants have evolved as natural alternatives that can employed as an emulsifying agent in the food processing industry. Biosurfactants of the lipopeptide, glycolipid, glycoprotein, glycolipopeptide types can emulsify a wide range of vegetable oils and fats in food processing with high emulsification index. This biomolecule has a beneficial impact on texture profile analysis and sensory attributes such as color, aroma, and taste evolution in baked goods. The research in this field is still in the lab, and additional research is needed before this natural alternative, biosurfactants, may be used in large industrial sectors.
Biosurfactants constitute a broad category of amphiphilic molecules being fabricated through plants, animals, and microorganisms. Their synthetic path customizes the molecular and functional properties, resulting in structural diversities. Biosurfactants are recognized as biomolecules with significant applications in the field of food industries for manufacturing diverse novel food formulations owing to their less toxicity, biodegradability, better interfacial and surface activities, better sensory parameters, specific bioactivity, better emulsifying properties, tolerable processing conditions, etc. Due to immense advantages, biosurfactants have considerable restrictions such as incompetency during scale-up processes, high cost of production due to expensive substrates, and patent rights. Generally, biosurfactants are categorized based on the following: (1) their molecular weight and (2) chemical composition. Globalization and the rapid escalation in the growth of the population have forced the concerned authorities to accelerate the production processes and investment opportunities in complex food supply dynamics to tackle the forthcoming menace of food security. Presently, researchers all over the globe are putting intense efforts into manufacturing next-generation biosurfactants for their application in food industries such as cookie formulations, bakery doughs, etc. The concept of rheology has broad application considering the food sector, though it has complexities owing to the non-ideal behavior of most of the food items. Studying the rheological properties of different food items particularly dough is often seen as challenging because of its varied nature and high dependency on numerous factors. The process of the development of dough is considered one of the most crucial steps during the conversion of flour into preferable products. Presently, the dynamic rheological analysis has evolved as a robust method for scrutinizing the structural and elemental features of wheat-flour-based doughs owing distinctive and sensitive responses toward structural alterations of wheat-flour-derived doughs. This article acknowledges different examples discussing the impact on the rheological properties when biosurfactants are being exploited following their interactions with the diverse components.
Biosurfactants are natural surface-active materials created by microorganisms. Biosurfactants can contribute several properties including antibacterial, antioxidant, emulsifying, and antiadhesive activities to the food in which they are incorporated. Biosurfactants have been employed in food formulations to enhance viscosity, extending the shelf life of the products, improving texture and flavor, as well as lowering the calorie value by substituting fat. This chapter summarizes the activities of biosurfactants as antioxidants in food, as well as the features of biosurfactants in boosting food quality and the variables impacting biosurfactant synthesis.
The chapter reviews the application of creep-recovery and oscillatory rheological tests in flour-based systems, including simple flour-water systems, and more complex ones, such as bread, cookies, and biscuits. A theoretical introduction about the fundaments and methods of linear viscoelastic rheology is presented, including general mathematical models and their application in flour-based systems. A summary of experimental conditions to perform the rheological tests is included. The functionality of flour-based systems is extremely dependent on their viscoelastic properties. Processes like mixing, pumping, lamination, and baking performance are strongly dependent on the system’s viscoelastic properties. However, the establishment of general and well-defined relationships among viscoelastic properties and specific functionalities is quite a difficult task, still in progress.
Abstract Refined wheat breads are popular staples worldwide. Although they have desirable texture, they generally attribute to a high glycemic index value. Adding whole‐grain flour to produce composite breads with both slower starch digestibility and ideal texture worth investigation. The present study investigated the pasting, farinographic and viscoelastic properties of the quinoa flour (QF)‐wheat flour (WF) composite dough. QF addition reduced the peak, final, breakdown and setback viscosities of the composite flour, indicating that starch gelatinization was inhibited and retrogradation was slowed. QF addition increased G′ and G′′, while decreased tan δ (G′′/G′), exhibiting that the elasticity prevailed over viscosity for the composite dough. Farinograph analysis showed that when QF addition exceeded 20%, the stability time decreased and weakening degree increased sharply. Although creep‐recovery tests showed that 40% of QF addition exhibited the highest resistance to deformation, it disrupted the gluten network and brought negative effects on the composite dough. Taken these together, the composite wheat dough containing 20% of QF exhibited ideal rheological properties comprehensively. These results might be useful to develop and optimize mixed‐grain breads with lower glycemic index.
Commercial insoluble tomato fibre (ITF) was incorporated in wheat-flour dough to prepare cookies at amounts of 2.50, 5, 7.50, and 10 %. It was demonstrated that all wheat dough samples exhibited non-Newtonian-thixotropic behaviors at shear rates from 0.001 to 1000 s-1. Besides, the oscillatory rheology analysis confirmed that the storage modulus predominated the loss one in the whole frequency range and increased significantly with the increase in the ITF concentration. Actually, the latter's incorporation from 0 to 10 % increased farinograph water absorption, pasting temperature and peak consistency, and decreased dough stability, amylograph pasting viscosities and fermentation parameters of all tested wheat flours. Furthermore, the ITF addition was proven to affect the formed cookies, indicating a significant increase in the samples' breaking strength and decrease in their spread ratio. The total polyphenol contents of the formed cookies ranged from 86.98 mgGAE/ 100 g to 376.02 GAE/g cookies. The ITF incorporation increased the antioxidant activities as measured by DPPH, ABTS and FRAP scavenging activities. Correlations between the analyzed parameters of the cookies' color and IC50 are statistically significant (p< 0.01), suggesting the possible use of ITF as an alternative source of bioactive compounds to improve the cookies' quality.
The research, evaluated the rheological properties of dough and final bread quality production, in function of time, made from wheat refined flour that was enriched with an oat dietary fiber in two dosages (WOF 6% and WOF 12%), spelt flour and two types of wholegrain flour: wholegrain (full milling) and wholemeal (one-step milling). The rheological measurements revealed that the highest instantaneous compliance (J0) was observed in the wholemeal sample and the lowest was in the WOF 6%. The lowest specific volume was observed in the wholegrain bread (0.82 cm³/g), while the highest was observed in the control white bread sample (1.60 cm³/g). The most rapid loss of moisture appeared in white bread. The moisture content was significantly influenced by the type of flour, day of storage and the interaction of these two variables (p ≤ 0.01). The hardest was the sample of wholegrain bread on the first and third day. The smallest pores were noticed in WOF 12% sample. In water extraction, white bread and WOF 12% were comparable and there were no significant differences between spelt bread and wholegrain bread. THE WOF 12% sample had the optimal ratio of health benefits and technological properties.
The aim of this study was to evaluate the effect of carob fiber on pasta properties. Common wheat flour was substituted with 0, 1, 2, 3, 4, and 5 g/100 g of carob fiber. Pasta properties including firmness, color, cooking time, sensory analysis, and antioxidant properties were evaluated. The results showed that carob fiber slightly increased the weight increase index and decreased the optimum cooking time. The lightness of pasta strongly decreased with the proportion of carob fiber, from 61.7 to 26.5 and from 55.8 to 38.6 for uncooked and cooked samples, respectively, whereas the total color difference changed from 24.4 to 38.6 and from 9.6 to 17.2, respectively. A linear decrease in pasta cutting force was observed as the proportion of carob fiber increased. The sensory evaluation of pasta showed that the additive decreased scores for pasta smell but increased scores for color evaluation. Carob fiber up to 4 g/100 g of wheat flour had little effect on pasta's overall acceptability and significantly increased total phenolics content and antioxidant activity of samples. Digestion in vitro caused an increase in total phenolics content and antioxidant activity.
The aim of this research was to study which kind of conformational changes in gluten proteins were induced by addition of four dietary fibre (apple-cranberry, cacao, carob and oat) by using FT-Raman spectroscopy and to find relationships between conformational changes and rheological behaviour of bread dough in mixing and extensional tests. Structural studies showed that all fibres induced formation of β-like structures between two protein molecules (pseudo-β-sheets) with the band at 1616 cm−1 in the Raman spectrum. According to Principal Component Analysis, the strongest dependence was between changes in gluten structure and two extensographic parameters (resistance to extension and extensibility). Resistance to extension was positively correlated with content of α-helix and pseudo-β-sheets, while a negative correlation was observed between the parameter and content of β-sheets and β-turns. Gauche-gauche-gauche conformation of disulphide bridges and ability of tyrosine residues to hydrogen bonds creation improved mixing properties as stability of dough.
Dietary fibres are regarded as the source of polysaccharides and antioxidants such as polyphenols. However, addition of dietary fibre to bread causes significant reduction in its quality. The bread quality is connected with the structure of gluten proteins. For this reason, Fourier transform Raman spectroscopy was applied to determine changes in structure of gluten proteins modified by seven dietary fibres. The fibres were added to model flour reconstituted with wheat gluten and wheat starch. The model flour was used to provide gluten proteins of definite structure. The obtained results showed that six out of seven fibres caused similar changes in β-turn structures. The appearance of the band at 1642 cm−1 and the shift toward lower wavenumbers of the band at 1670 cm−1 in the difference spectra indicated hydrogen bonding of carbonyl groups in β-turns leading to protein folding/aggregation. Addition of fibre preparations caused also changes in conformation of disulfide bridges (S–S), corresponding to transformation to trans-gauche-gauche and trans-gauche-trans conformations at the expense of the stable gauche-gauche-gauche conformation. The S–S bonds in less stable conformations were formed inside the protein complex as well as between protein complexes in the form of β-structures. Generally, the observed changes in gluten proteins after addition of dietary fibres were results of interactions between fibre polysaccharides and gluten proteins rather than between polyphenols and gluten proteins. Copyright © 2015 John Wiley & Sons, Ltd.
The main objectives of this study were to increase the fiber content of noodles using oat flour and to determine the effects of oat flour on the rheological properties of the dough, and the physical properties, and cooking and sensory quality of the noodles. Wheat flour was replaced with different levels of oat flour (0, 10, 20, 30 and 40% w/w). With increasing oat flour level, the following changes occurred: the dough became softer, more viscous and less elastic, and the amount of water required to make the dough increased; dough development and stability times decreased; dried noodles became darker in color and became more brittle; optimum cooking time and cooking loss increased; the hardness and adhesiveness of the cooked noodles decreased while their cohesiveness increased and the smoothness of noodle surface decreased. In general, to preserve the overall quality of the noodles, inclusion of 20% oat flour in the noodle recipe is suggested.
In this study, the rheological properties of gluten-free doughs from rice flour containing different amounts of carob flour were investigated. Water added changed in response to the carob amount. Dynamic oscillatory and creep tests were performed in order to gain knowledge on the rheological behaviour of doughs, which is essential for the control of the bread-making procedure and the production of high-quality bread. Simple power law mathematical models were developed in order to evaluate the effect of carob and water added in dough rheological behaviour. Creep data evaluation demonstrates that an increase in water content decreased the resistance of dough to deformation and, therefore, dough strength, whereas carob flour increased the elastic character and structure strength of the dough. This was also found in dynamic oscillatory tests. Increased amounts of carob flour led to an increase in bread dough elastic character since fibre addition elastifies and strengthens the dough structure. Moreover, doughs exhibited a solid-like viscoelastic character, with the storage modulus (G′) predominant over the loss modulus (G″). Dough rheological properties have an important effect on baking characteristics. Rheological experiments and applied mathematical models can provide us with good knowledge of rheological behaviour and dough viscoelasticity prediction. Therefore, dough samples containing carob-to-water ratios of 10:110 and 15:130 can be considered to possess a balance between the viscous and elastic properties compared to the other samples.
A seven-parameter regression model was developed to determine changes in the shape of the Brabender extensograph curve as a result of supplementation of wheat dough with carob fibre and oat wholemeal. The shape of the curve, close to an inverted parabola, was well described by a cubic polynomial function. The exceptions were the initial and final sections of the curve, for the representation of which two exponential functions were used. Under the effect of the fibre-rich additions, the strongest variation was observed in the polynomial function parameters describing the slope and deflection of parabolic arms of the extensograph curve and the position of its peak, while the parameters showing the final course of the curve were subject to only slight changes. The reactivity of the additions during dough proving had a much stronger effect on the model parameters than on the variation of the maximum resistance and extensibility of the dough. The results indicate that the proposed model can be a useful tool for improving the analysis of extensional behaviour of bread dough.
Farinograph and extensograph tests were applied to determine the effect of carob fibre and oat wholemeal on the rheological properties of wheat flour dough, and characterisation of relationships between the results of the tests was performed. The applied additions of carob fibre (1–5%) and oat wholemeal (5–25%) increased the water absorption of the dough within nearly identical ranges (56–59%). Enrichment with carob fibre made the dough more rheologically stable during mixing compared to dough with oat wholemeal. In the extension test, dough with an admixture of carob fibre was more resistant, but it was less extensible than dough with oat wholemeal.Analysis of relationships of the extensograph traits to the farinograph ones revealed that longer periods of development of dough enriched with the additions under examination involved the formation of a looser dough structure, as a result of which its resistance to extension, ratio number and energy decreased and the dough extensibility increased. Opposite effects were caused by increasing farinograph elasticity and its loss. The degree of softening, negatively correlating with resistance, ratio number and energy, coupled with water absorption or with loss of elasticity, permitted their more accurate prediction. In turn, combining in a regression model of water absorption with development time or with elasticity was the most suitable for predicting dough extensibility.
The aim of the present research is the evaluation of the influence of carob seed and the methanolic, petroleum ether and crude polyphenols extract of carob pods on glucose tolerance curve in addition of studying the glycaemic index of carob pods. The aim also includes assessing the proximate analysis of carob pods and determination of total polyphenols and condensed tannins content. The results revealed that total polyphenol in the prepared crude polyphenol was 18.610 g/100 g, while condensed tannins in crude polyphenol was 3.808 g/100 g. Proximate analysis revealed that carob pods have high percentage of carbohydrates (57.71) followed by crude fiber (17.21) and protein (9.69). Fat was the lowest component 0.31 %. Administration of crude polyphenol extract or carob seeds powder to male rats showed significant reduction of the rise in blood glucose after 1/2, 1 and 2 hours with different degrees when compared with control group. Oral administration of methanol or petroleum ether extract of carob pods showed no improvement in blood glucose response compared with control. Glycaemic index of carob pods was evaluated as 83.4%.
Recently, insoluble fibre from carob pulp has been found to affect blood lipids in animals in a similar manner as soluble dietary fibre.
To investigate whether a carob pulp preparation containing high amounts of insoluble fibre has a beneficial effect on serum cholesterol in humans.
Volunteers (n = 58) with hypercholesterolemia were recruited to participate in a randomised, double- blind, placebo-controlled and parallel arm clinical study with a 6 week intervention phase. All participants consumed daily both, bread (two servings) and a fruitbar (one serving) either with (n = 29) or without (n = 29) a total amount of 15 g/d of a carob pulp preparation (carob fibre). Serum concentrations of total, LDL and HDL cholesterol and triglycerides were assessed at baseline and after week 4 and 6.
The consumption of carob fibre reduced LDL cholesterol by 10.5 +/- 2.2% (p = 0.010). The LDL:HDL cholesterol ratio was marginally decreased by 7.9 +/- 2.2 % in the carob fibre group compared to the placebo group (p = 0.058). Carob fibre consumption also lowered triglycerides in females by 11.3 +/- 4.5% (p = 0.030). Lipid lowering effects were more pronounced in females than in males.
Daily consumption of food products enriched with carob fibre shows beneficial effects on human blood lipid profile and may be effective in prevention and treatment of hypercholesterolemia.
Fibre-enriched baked goods have increasingly become a convenient carrier for dietary fibre. However, the detrimental effect of fibres on dough rheology and bread quality continuously encourages food technologists to look for new fibres. The effect of several fibres (Fibruline, Fibrex, Exafine and Swelite) from different sources (chicory roots, sugar beet and pea) on dough mixing properties when added singly or in combination has been investigated by applying a response surface methodology to a Draper-Lin small composite design of fibre-enriched wheat dough samples. Major effects were induced on water absorption by Fibrex that led to a significant increase of this parameter, accompanied by a softening effect on the dough, more noticeable when an excess of mixing was applied. Conversely, Exafine increased water absorption without affecting the consistency and stability of dough, which even improved when combined with Swelite. Fibruline showed little effect on dough mixing parameters, but showed synergistic effects with pea fibres. The overall result indicates that the use of an optimised combination of fibres in the formulation of fibre-enriched dough allow improving dough functionality during processing.
The results presented in this paper concern doughs prepared from an industrial soft wheat flour mixed with water using the traditional Brabender farinograph. These doughs are characterized using dynamic rheometrical measurements. In parallel, an innovative microscopy study, the Environmental Scanning Electron Microscope (ESEM) is investigated and found to be very well-suited for the observation of such doughs. A change in the slope of the curve giving the maximum of consistency is observed at a typical water content, due to the presence of excess free water. The main rheometrical characteristics |η*| and tan δ are exhibited for this kind of dough. Their adequacy to differentiate between various doughs is emphasized. Parameters such as mixing time, water content and rest time are shown to influence both the rheometrical properties and the microscopic structure of doughs. Changes generated by mixing are interpreted at the molecular level. It is shown that the study of the microstructure is essential to compare the evolution of different doughs.
Pinitol and chino-inositol exert insulin-like effect by mediating post-receptor signaling pathway. Total chino-inositol concentrations, including pinitol, chino-inositol, and their derivatives, were determined in 115 natural and food materials to identify economical sources for mass production of pinitol. Carob pod, Bougainvillea, soy whey, and soybean oligosaccharides were rich sources of chino-inositol. Pinitol was isolated from soy whey and carob pod, considered as economically viable sources, by chromatographic separation using activated carbon. Soy and carob pinitols had same chemical structure as that of reference pinitol based on HPLC and NMR results. Oral administration of soy pinitol and carob pinitol (10 mg/kg) significantly decreased blood glucose at 2-6 hr in streptozotocin-induced diabetic rats. These results suggest pinitol isolated from soy whey and carob pod could be beneficial in controlling blood glucose in animal model of diabetes mellitus.
High-fiber, high-complex carbohydrate diets have been useful in regulating blood lipids, blood glucose, and insulin response - factors that are significant in the prevention and treatment of coronary heart disease and diabetes. Breads and pastas with increased levels of dietary fiber (including β-glucans) were produced by substituting barley flour fractions enriched with β-glucan for 5, 20, or 40% of the standard flours. The dry milled/sieved and water-extracted barley fractions contained 42 and 51% total dietary fiber (TDF) and 19 and 33% β-glucans, respectively. Bread, in which the dry milled/sieved barley flour fraction replaced 20% of the standard flour, contained 4.2 times the TDF, 7.6 times the total β-glucans, and 0.8 times kcal per serving compared to the control. This bread was judged acceptable in laboratory acceptance tests although loaf volume was reduced and color was slightly darker than the control. Pastas in which barley fractions replaced 20 or 40% of the wheat semolina provided 5.4 to 10.4 g TDF per serving (compared with 2 g in the control). These pastas, which could be labeled as good or high-fiber sources, respectively, had acceptable sensory quality although they were darker in color than the control. Kilocalories in a serving of these pastas with 20 and 40% flour substitution were 11 and 16%, respectively, lower than in the control. When the water-extracted barley fraction was substituted in breads and pastas, color scores and acceptability improved over those containing the dry milled/sieved barley fraction.
The relaxation properties of flour-water-salt doughs prepared from four different flour types (weak medium, strong, and extra strong) at different water absorption levels from 58 to 66% with protein contents of 10.0, 10.9, 13.2, and 11.8%, respectively, were studied by imposing varying strain amplitudes of 0.1-29%. Oscillatory tests in the linear viscoelastic region of the 66% absorption strong and weak dough cannot distinguish between the two types of dough. The inability to differentiate between dough types also applied to oscillatory tests on 58% absorption weak and 66% absorption strong doughs. However, the relaxation modulus of dough (extending over time) behaved quite distinctively at high strains, where dough samples experience large deformations. At strain amplitudes of less than or equal to 0.1% (i.e., in the linear viscoelastic region), different dough types behaved similarly. Likewise, the relaxation modulus completely relaxed at sufficiently long times. The magnitude of the modulus at intermediate- and high-strain amplitudes were in the order: extra strong > strong > medium > weak, indicating a higher level of elasticity in the extra strong dough samples despite its lower protein content. The relaxation times spectrum of the weak flour, extracted from the relaxation modulus data, reveals a broad relaxation process. The stress relaxation data are very reproducible at high-strain amplitudes (approximate to 1-15% for up to 3 x 10(3) sec). This work demonstrated, for the first time, the consistency in oscillatory and relaxation measurements for dough. It also clearly showed that linear viscoelastic data, although important in the characterization of time scales in dough, are largely irrelevant in differentiating between dough types. Furthermore, without proper care, a false steady-state behavior can be obtained with standard viscometric measurements due to slippage at the dough-plate interface.
The rheological properties of seventeen pure European wheat cultivars were analyzed and evaluated in relation to the bread volume. Rheological testing included two empirical rheological methods, farinograph and alveograph, besides more fundamental rheological methods, more specifically creep-recovery and dynamic oscillation measurements.
The four rheological methods revealed large differences in dough rheological properties among the 17 wheat cultivars. Phase angle δ and the moduli were strongly correlated. The dynamic oscillation parameters also correlated significantly with protein content, Zeleny sedimentation value, damaged starch content and farinograph water absorption. A non-linear relationship (power) between the maximum creep or recovery strain and the dynamic moduli was found and this for both shear stresses (100 and 250 Pa). Phase angle δ showed a positive relationship with the maximum creep or recovery strain. The dynamic oscillation parameters could be related to the bread volume. Phase angle δ could explain almost 70% of the variance in bread volume among the wheat cultivars. The dynamic moduli showed an inverse relationship with the bread volume. A non-linear relationship with the bread volume could be established for G’ (r²=0.75), G” (r²=0.72) and |G*| (r²=0.74).
The rheological properties of 17 pure European wheat cultivars were analyzed and evaluated in relation to the bread volume. Rheological testing included two empirical rheological methods, farinograph and alveograph, and more fundamental creep-recovery experiments at;hear stresses of 100 and 250 Pa. Principal component analysis on the farinograph and alveograph results showed that a wide range of rheological properties was present among the wheat cultivars. Correlation analysis pointed Out that creep-recovery parameters showed significant correlations with protein content, Zeleny sedimental value, farinograph water absorption. alveograph extensibility. and bread volume. Among the rheological parameters, maximum recovery strain at it shear stress of 250 Pit showed the highest significant correlation with the bread volume (r = 0.790**). Variables were combined to predict the bread volume by Multiple linear regression. A combination of protein content. farinograph water absorption, and alveograph P/L showed the best prediction (r(2) = 0.80). taking into account the creep-recovery parameters. the best prediction of the bread volume (r(2) = 0.74) was obtained for a combination of the maximum recovery strain at a shear stress of 250 Pa with one other quality parameter (Zeleny sedimentation value, farinograph water absorption, or alveograph W).
Dynamic measurements and retardation tests were combined to characterise the linear viscoelastic behaviour of wheat flour dough in the 10−5–102rad/s frequency range. Analysis of the data provided the Newtonian steady-state viscosity, the steady-state compliance, the terminal relaxation time, the viscoelastic plateau compliance and a measure of the upper frequency limit of the viscoelastic plateau. The influence of dough water content and composition of high molecular weight glutenin subunits on dough viscoelasticity was studied. Both factors affected dough viscoelasticity in a similar and remarkable way. In particular, the same inverse relationship between steady-state viscosity and compliance, and the same power law relationship between steady-state and plateau compliances, was found to hold whether the variability was due to high molecular weight glutenin subunits or to dough water content.
The present work was undertaken to observe the effects produced on the structure of gel, dough and bread crumb by dietary fibres (DF), either from natural origin, such as locust bean gum, and fructo and gluco-oligosaccharides, or from synthetic preparation, such as carboxymethylcellulose having thickening, gelling properties. Rheological, viscometric, sensory and image-analysis investigations were carried out in order to study the physical/functional performances of final and intermediate products, and to identify the main actions of fibres at replacement level from 0% up to 12%. Avrami non-linear regression equation was chosen as useful mathematical model to properly study bread crumb firming kinetics. Significant relationships were found between several parameters obtained from the different analyses performed on raw materials, intermediate and final products. Data from factor analysis strongly proposed the viability of locust bean and carboxymethylcellulose/prebiotic blends as sources of DF for the production of healthy baked goods with extended shelf-life.
Measurements of creep-recovery of flour-water doughs were made using a dynamic mechanical analyzer (DMA) in a compression mode with an applied probe force of 50 mN. A series of wheat flour and blend samples with various breadmaking potentials were tested at a fixed water absorption of 54% and farinograph optimum water absorption, respectively. The flour-water doughs exhibited a typical creep-recovery behavior of a noncross-linked viscoelastic material varying in some parameters with flour properties. The maximum recovery strain of doughs with a fixed water absorption of 54% was highly correlated (r = 0.939) to bread loaf volume. Wheat flours with a large bread volume exhibited greater dough recovery strain. However, there was no correlation (r = 0.122) between maximum creep strain and baking volume. The maximum recovery strain of flour-water doughs also was correlated to some of the parameters provided by mixograph, farinograph, and TA-XT2 extension.
The applications of rheology to the main processes encountered during breadmaking (mixing, sheeting, fermentation and baking) are reviewed. The most commonly used rheological test methods and their relationships to product functionality are reviewed.It is shown that the most commonly used method for rheological testing of doughs, shear oscillation dynamic rheology, is generally used under deformation conditions inappropriate for breadmaking and shows little relationship with end-use performance. The frequency range used in conventional shear oscillation tests is limited to the plateau region, which is insensitive to changes in the HMW glutenin polymers thought to be responsible for variations in baking quality. The appropriate deformation conditions can be accessed either by long-time creep or relaxation measurements, or by large deformation extensional measurements at low strain rates and elevated temperatures.Molecular size and structure of the gluten polymers that make up the major structural components of wheat are related to their rheological properties via modern polymer rheology concepts. Interactions between polymer chain entanglements and branching are seen to be the key mechanisms determining the rheology of HMW polymers. Recent work confirms the observation that the dynamic shear plateau modulus is essentially independent of variations in MW of glutens amongst wheat varieties of varying baking performance and also that it is not the size of the soluble glutenin polymers, but the secondary structural and rheological properties of the insoluble polymer fraction that are mainly responsible for variations in baking performance. Extensional strain hardening has been shown to be a sensitive indicator of entanglements and long-chain branching in HMW polymers, and is well related to baking performance of bread doughs. The Considere failure criterion for instability in extension of polymers defines a region below which bubble walls become unstable, and predicts that when strain hardening falls below a value of around 1, bubble walls are no longer stable and coalesce rapidly, resulting in loss of gas retention and lower volume and texture. Strain hardening in doughs has been shown to reach this value at increasingly higher temperatures for better breadmaking varieties and is directly related to bubble stability and baking performance.
Oatmeal and other whole-grain oat products are a tasty, a convenient, and an economical source of nutrients that can provide proven health benefits, including benefits on blood cholesterol, blood pressure, blood glucose metabolism, satiety, and gastrointestinal health.
The aim of the present study was to improve the quality of fibre-enriched wheat breads by enzymic treatment of the fibre fraction. The suitability of different enzymes in fibre-enriched baking and their effects on the dietary fibre content and the ratio of insoluble: soluble fibre content of the breads were studied. The enzyme preparations used were a hemicellulolytic culture filtrate of Trichoderma reesei, a specific (pI 9) xylanase of T reesei and Fermizyme, an α-amylase preparation containing a standardised level of hemicellulase activity. Rye bran was extracted in water (10% (w/w) suspension) to determine the solubilities of the β-glucans and pentosans. Addition of T reesei culture filtrate significantly increased the amount of extractable pentosan obtained from nonautoclaved rye bran. Rye bran supplementation (5%) of wheat flour increased the farinograph absorption and dough development time, but had little or no effect on stability and softening of the dough. The added enzymes decreased dough stability and increased softening. Addition of enzymes caused significant differences in the stickiness of the wheat doughs both with (P<0·003) and without (P<0·001) rye bran. Fermizyme significantly increased the stickiness of wheat doughs both with and without rye bran. The baking results of the fibre-enriched breads were improved by the added enzymes. Addition of T reesei culture filtrate increased the specific volume of the wheat breads both with and without rye bran by almost 20%. Enzyme mixtures were more efficient than individual xylanase in softening the bread crumb and reducing the staling rate of wheat breads both with and without rye bran. Incorporation of enzymes reduced the total dietary fibre content of the breads, but at least doubled the amount of soluble pentosan. The proportions of fluorescent cell walls in the breads were detected by microscopical image analysis. Enzyme addition caused the surface area of insoluble cell walls originating from wheat flours to decrease, suggesting that the enzymes exert more effects on wheat endorsperm cell walls than on bran particles. © 1998 SCI.
The rheological characteristics of twenty wheat flour samples obtained from four organic flour blends and a non-organic control were compared in relation to their ability to predict subsequent loaf volume in the baked bread. The flour samples considered had protein contents that varied between 11–14 g/100 g. Four different rheological methods were employed. Oscillatory stress rheometry on the protein gel extracted from the wheat flour, oscillatory stress rheometry and creep measurement on undeveloped dough samples and biaxial extensional measurements on simple flour–water doughs. None of the fundamental rheological parameters correlated with loaf volume. There was a correlation between the storage modulus of the gel protein and storage modulus for the undeveloped dough (r = 0.85). There was a weak negative correlation between protein content and biaxial extensional viscosity (r = −0.62). Stepwise multiple regression related loaf volume to dough stability time (measured on the Farinograph) and tan (phase angle) for the undeveloped dough samples (overall model r2 = 0.54). The results indicate that the four rheological tests considered could not be used as predictors of subsequent loaf volume when the bread is baked.
Empirical and fundamental rheological measurements were made on fresh and frozen dough to study the effects of freezing and frozen storage conditions. Frozen dough was stored at two different temperatures, −18 °C and −30 °C, and for 1, 7 and 28 days. Four dough formulations were tested: a standard wheat dough, a fibre-enriched wheat dough, a standard gluten-free dough and a gluten-free dough containing amaranth flour. No yeast was used in any formulation. The wheat dough is more affected by freezing and by the first days of storage whereas the gluten-free dough is more affected by a longer storage time. A storage temperature of −30 °C alters dough rheological properties more than a storage temperature of −18 °C. The addition of dietary fibres to the wheat dough increases its resistance to freezing and frozen storage. The addition of amaranth flour to gluten-free dough also increases its resistance to freezing but decreases its resistance to storage conditions.
Cereal Chem. 74(4):489-494 Undeveloped wheat dough is essentially wheat flour that has become fully hydrated without being deformed. The rheological properties of this material were compared to dough (developed dough) made using the standard method involving a farinograph. Flow behavior of undeveloped and developed dough samples made from hard and soft wheat flours were tested using creep tests, frequency sweep oscillatory tests, and tempera-ture sweep oscillatory tests. All experiments showed that the undeveloped dough requires less resistance for deformation than developed dough. The differences are due to the energy input received by the developed dough and the influence of this factor in forming the protein matrix associated with developed dough. To attain a comparable state as the dough made in the farinograph, an energy input must be applied to the undeveloped dough material. Understanding the differences between undeveloped and developed dough may lead to new products, equipment, and processes in the bakery industry.
Linear viscoelastic properties (LVP) were determined for five durum wheat doughs and five common wheat doughs (representing
four different classes of Canadian common wheat) of different strength using creep testing. A creep time of 10,000 s was sufficient
to reach a state of steady state flow for all of the doughs. Creep compliances were analyzed in terms of a Burgers model.
For the durum doughs, the entire elastic compliance curve was shifted to higher values as the strength of the dough (as measured
by extensigraph) decreased, while the steady state viscosity increased with strength. For common wheat doughs, the elastic
compliance curves were steeper and the steady state viscosities were lower than for durum doughs of comparable extensigraph
strength. The retardation strengths associated with a maximum in the retardation spectra were lower for the stronger durum
doughs than for common wheat doughs of comparable strength. Differences in the LVP between durum and common wheat doughs of
similar extensigraph strength were interpreted in the context of physical gels with crosslinks and entanglements, whose contributions
to material properties are difficult to distinguish in short-time creep or dynamic measurements. The increased extensibility
of common wheat doughs relative to durum doughs of comparable extensigraph strength was attributed to a higher molecular weight
fraction in the polypeptide chains, similar in some respects to end-linked bimodal polymer networks. The idea of considering
these doughs as physical gels was supported by their stress relaxation behavior.
The general dynamic mechanical properties of wheat flour doughs have been investigated for a range of strains over a frequency spectrum of 0.032–32 Hz. An approximately linear stress-strain relationship was found to hold at the lower range of strains imposed. Departures from the linear response of the dough are explained in terms of a protein chain-starch granule interaction and the accompanying time dependence in terms of a stress-biased diffusion process. The influence of water and temperature on the dynamic moduli are shown, indicating that a frequency-temperature and a water absorption-frequency superposition principle is applicable. The transient stress relaxation modulus is calculated from the dynamic moduli to demonstrate the ability of dynamic methods to investigate the time scale inaccessible to transient techniques.
Dietary fibre is a common and important ingredient of a new generation of healthy food products demanded more each day by customers. Dietary fibre increases the nutritional value of bread but usually at the same time alters rheological properties of dough and, finally, the quality and sensorial properties of bread. The present work investigates the effect of some purified dietary fibres from different origins (orange, pea, cocoa, coffee, wheat and microcrystalline cellulose) on the rheological properties of wheat flour dough and the final quality of breads. The study of the rheological behaviour of the dough was performed by means of a consistograph and an alveograph. Bread quality was determined by means of texture, colour and specific volume measurements after baking under controlled conditions. The influence of fibre on bread sensory evaluation was established. Dietary fibre additions, in general, had pronounced effects on dough properties yielding higher water absorption, mixing tolerance and tenacity, and smaller extensibility in comparison with those obtained without fibre addition (in the control bread). Regarding the effect on bread properties, the fibre always enhanced the shelf life, as textural studies revealed. Sensory evaluations revealed that dietary fibres, with the exception of those from coffee and cocoa, can be added to flour at the level of 2% without deterioration of the bread palatability in comparison with white flour bread. Additions of 5% could imply the use of some additives to correct the rheological properties of dough.
The effect of hydrocolloids on dough rheology and bread quality parameters in gluten-free formulations based on rice flour, corn starch, and sodium caseinate (control) was studied; the hydrocolloids added at 1% and 2% w/w (rice flour basis) were pectin, carboxymethylcellulose (CMC), agarose, xanthan and oat β-glucan. The study on rheological behavior of the doughs containing hydrocolloids, performed by farinography and rheometry, showed that xanthan had the most pronounced effect on viscoelastic properties yielding strengthened doughs; addition of xanthan to the gluten-free formulation resulted in a farinograph curve typical of wheat flour doughs. Moreover, among the preparations supplemented with hydrocolloids the elasticity and resistance to deformation of dough, as determined by oscillatory and creep measurements, followed the order of xanthan > CMC > pectin > agarose > β-glucan. The type and extent of influence on bread quality was also dependent on the specific hydrocolloid used and its supplementation level. Generally, the volume of breads increased with addition of hydrocolloids except for xanthan; with increasing level of hydrocolloids from 1% to 2% the loaf volume decreased except for pectin. Empirical methods were used for evaluation of porosity and elasticity of the crumb; high values of porosity were found for breads supplemented with CMC and β-glucans at 1% concentration, and pectin at 2%, whereas high crumb elasticity was exhibited by CMC, pectin and xanthan at 2%. An increase in lightness (L value) of crust was observed with the addition of β-glucan at 1%, whereas the whiteness of crumb was improved with inclusion of xanthan. Sensory evaluation by a consumer panel gave the highest score for overall acceptability to the gluten-free formulation supplemented with 2% CMC. In most cases, addition of hydrocolloids did not affect significantly the water activity (aw) values of crumb. During storage of breads a reduction in aw and an increase in firmness of crumb (compression tests) were observed. Compared to the control formulations, crumb firmness was not alter significantly with addition of pectin, CMC and agarose (at 1–2%), and of β-glucan (at 1%); instead, addition of xanthan (1–2%) as well as β-glucan (2%) resulted in crumb hardening.
Oat (Avena sativa L.) is a source of many compounds that exhibit antioxidant activity. Vitamin E (tocols), phytic acid, phenolic compounds, and avenanthramides are the most abundant antioxidants in oat, and flavonoids and sterols are also present. These antioxidants are concentrated in the outer layers of the kernel. Several in vitro tests have been used to evaluate antioxidant activity of oat extracts. A few examples show that an oat-containing diet boosted the antioxidant capacity of serum or meat in animals. Avenanthramides may be a plant defense response, as these compounds are induced in oat leaves by rust spores or elicitors. Antioxidants function in helping to maintain the stability of processed oat products, and oat can stabilise oils and fats against rancidity. Possible future research should be aimed at increasing antioxidants by plant breeding and through a nutritional genomics approach. Additionally, we need to acquire knowledge about the bioavailability and function of antioxidants in human and animal systems. Methods for fractionation of oat to produce antioxidant co-products along with other high-value components should also be studied.
A good correlation has become evident between fibre consumption and the reduction of coronary heart-related diseases and diabetes incidence. However, fibre intake is commonly lower than recommended. In consequence, the development of foods with high fibre content should be desirable. The potential use of various commercial fibres (carob fibre, inulin and pea fibre), as fibre-enriching agents in breadmaking, is reported. The effects of the addition of these fibres to wheat flour on the viscoelastic properties of dough and both mixing and proofing behaviour is presented. Bread evaluation revealed that carob and pea fibre supplementation, although decreasing specific loaf volume (very slightly in the case of carob fibre), conferred softness to the bread crumbs. In addition, sensory evaluation showed that consumer panellists judged these fibre-enriched breads as acceptable. Therefore, their use, especially carob, allows an increase of the daily intake of fibre without promoting negative effects on the rheological properties of doughs or quality and overall acceptability of the resulting breads. The whole study indicates that these three fibres can be used as additives in breadmaking in order to fortify the diet.
The effects of addition of purified total gliadin and its subgroups (α-, β-, γ- and ω-gliadins) on the dynamic rheology of gluten were investigated. The frequency sweeps of gluten with added α-, β-, γ- and ω2-gliadins showed unexpected increases in the magnitude of G′ and G′′, suggesting stiffening of the native gluten. Conversely, a reduction in the magnitude of G′ and G′′ occurred upon addition of the total gliadin fraction and the ω1-gliadin, implying softening of the gluten. Addition of individual gliadin fractions increased the values of slope log G′ vs log frequency, suggesting increased concentrations of uncrossed-linked material compared with the native gluten. There were significant differences in the slope values for individual gliadin fractions. The increasing order of slopes for different gliadins was: β- >γ- >α- =ω1>ω2, indicating that glutens containing ω- and α- gliadins are relatively less crossed-linked than those containing β- and γ-gliadins. The dynamic moduli, G′ and G′′, of cv. Hereward gluten showed significant positive relationships with Mixograph parameter peak dough resistance (PDR), and loaf volume for gliadin subgroups added to cv. Hereward flour.
Rheological properties of semi-sweet biscuit doughs from eight wheat cultivars were studied, and related to the dimensional changes of biscuits after cutting and baking. The tested cultivars were selected in order to represent a wide diversity in biscuit baking performance, and were grown with low use of N-fertiliser in three successive years. A standard recipe for semi-sweet biscuit dough was used, and the amount of water added was adjusted to the water absorption capacity. The rheological properties of the dough were characterised by creep recovery and oscillation. The fundamental methods showed that maximum strain at creep, recovery, storage modulus G′, and phase angle δ were significantly influenced by the tested cultivars. The ranking of the cultivars according to phase angle δ was identical in each of the years investigated 3 which indicates that phase angle δ reflects differences in structural properties with genetic control. Multivariate regression of flour physiochemical, dough rheological, and biscuit baking characteristics showed that a decrease in biscuit length was correlated under several rheological parameters, including phase angle δ, Farinograph and creep recovery parameters. Sedimentation value was the only physiochemical flour characteristic with considerable influence on the model. Validation of the partial least squares-model including all samples from the 3 years gave only a weak correlation (r=0.58), whereas when each single year was evaluated separately, the correlation increased considerably (r=0.71 and 0.87).
The rheological characteristics, static and dynamic mechanical properties of amaranth, quinoa and oat doughs and the relative size distribution of their polymeric proteins were evaluated. For the sake of comparison, semolina dough rheological and mechanical properties and the relative size distribution of proteins were also determined.From rheological results it was inferred that the tenacity of amaranth, oat and quinoa dough samples was lower than that of semolina dough. The elastic modulus (Ec) of amaranth, oat and quinoa doughs was higher than that of semolina dough. Amaranth and quinoa G′ was found to be similar and significantly higher (p < 0.05) with respect to that of oat dough at a moisture of 30%. The G″ of amaranth, quinoa and oat doughs showed different values. The highest G″ value was recorded for the amaranth dough while the lowest one was shown by oat. For semolina dough, the G′ and G″ values were significantly lower than those of all the other dough samples. Moreover, at low and medium frequencies, tan δ values of oat and quinoa doughs were statistically comparable and significantly lower (p < 0.05) than that of amaranth and semolina doughs. At high frequencies, tan δ values of investigated samples were different among them and the highest value was detected for amaranth, followed by semolina, quinoa and oat. Results of the size distribution of proteins in amaranth, quinoa, oat and semolina doughs were expressed as the proportion of “unextractable polymeric protein” (UPP). Unextractability of semolina dough proteins (61%) was greater with respect to the others, followed by amaranth (40.7%), oat (24%) and quinoa (10.1%).
The effect of adding low (105 Da) or high (2.03 × 105 Da) molecular weight barley β-glucans in two wheat flours of different breadmaking quality were studied. Mechanical spectra and creep–recovery analysis data within (low stress) and out (high stress) of the linear viscoelastic region were obtained. The results revealed that the rheological behavior of β-glucan-enriched doughs depend on concentration and molecular weight of the polysaccharide as well as on the flour type used. Addition of β-glucan increased the G′ values of the good breadmaking quality flour doughs, whereas decreased the G′ of the poor quality wheat cultivar. Supplementation with β-glucans increased the resistance to deformation, flowability and elasticity of the doughs under low stress. Significant correlations between frequency sweep and creep–recovery parameters of optimally developed doughs from both flours were found. The addition of β-glucan in the dough recipe of the poor breadmaking wheat flour may result in similar rheological responses to those obtained from a non-fortified good breadmaking quality wheat flour.
The research aims at optimising mixtures of fibres from different sources and degree of processing meeting acceptable dough viscoelastic standards to design low-calorie wheat bread formulations. Effects of soluble—inuline (FN)—, partially soluble—sugar beet (FX), pea cell wall (SW)—and insoluble—pea hull (EX)—dietary fibres on wheat dough mechanical, extensional and surface-related functional profile have been investigated by response surface methodology, and the parameters derived from the functional profile correlated. Flour replacement at different levels (from 6 up to 34%) by fibres significantly change dough machinability and extensional behaviour of the resulting hydrated flour-fibre blends. SW had no relevant significance on dough viscoelasticity when added singly. FX, a fibre with good hydration properties and small particle size, provided the most beneficial effects on dough textural profile, when added singly, especially for the prominent and suitable decrease in gumminess and no significant adverse effects on main mechanical, surface and extensional properties. Caution should be paid to both the pair FX–SX and single EX because of the adverse shortening and hardening effects they respectively induced. Addition of EX to FX-flour blends is not recommended because of the deleterious effect on dough mechanical properties and extensional behaviour, particularly in reducing springiness and cohesiveness. The association of EX and SW, both from pea is strongly encouraged to minimize adhesiveness and stickiness.
The aim of this experimental work was to evaluate the effect of inulin addition on the rheological properties of common wheat doughs and bread quality. Three commercial fructan products of different number average degree of polymerisation (DPn) were used (DPn = 10 for inulin ST; DPn = 23 for inulin HP and HP-gel). Inulin contents from 2.5 to 7.5% on dry matter (wheat flour plus inulin) were used. Dough rheological properties were investigated using farinograph and dynamic rheological measurements. Upon addition of dietary fibre (DF), significant increase in mixing time and stability, and decrease in water absorption were recorded. Inulin ST exerted greater effect on water absorption than HP products.Inulin with high DP determined large changes in linear viscoelastic properties of dough. The storage modulus (G′) gradually increased and tan δ decreased with increasing levels of inulin HP and HP-gel, which contribute to the overall dough elasticity and strength. The increase in solid-like behaviour with DF content prevented expansion of wheat dough during the fermentation stage. No significant differences were observed between sample HP and HP-gel. Enrichment with inulin ST led to lower changes in linear viscoelastic properties of dough at farinograph water absorption than inulin HP. Bread volume was significantly reduced and crumb hardness was enhanced by inulin HP level in the range 5–7.5%. When inulin ST was added to a flour suitable for breadmaking, a trend of increasing bread volume with the increase of DF content was found.
There is an increasing awareness about the role of fibres as multifunctional substances, positively affecting the activity of the human body. From the structural point of view, insoluble fibres are known to have a strong impact on food texture. This work is part of a broader project aimed at understanding the role of fibres from different sources in traditional cookies delectableness. The impact on cookie dough characteristics, when enriched with dietary fibre, was evaluated by dynamic oscillatory tests, transient uniaxial extensional viscosity measurements and texture profile analysis. Three different sources of fibre were added: oat from cereals, orange from fruits and pea from legumes, at contents ranging from 0 to 10 g.In terms of processibility, there were serious difficulties in processing some of these doughs, especially those with fibre addition levels over 8 g for oat and orange and 9–10 g for pea. However, the results for the mechanical spectra of these doughs are similar to that of the standard dough without fibre. Tests in compression with a 4 mm cylinder in a 25 mm flask filled with dough showed to be more sensitive than oscillatory tests but still the results were somewhat difficult to interpret in terms of describing the differences in the processing behaviour of these doughs. Thus, extensional uniaxial tests were performed (for the first time in this type of materials, i.e., with no developed gluten) and showed to be suitable to describe the modification in dough structure, showing an increase of extensional viscosity for the dough with orange or oat fibre at levels of 4, 8 and 10 g, whereas for the pea fibre dough, no significant changes on the extensional behaviour were observed for formulations with up to 10 g of fibre, which was in general agreement with the processibility studies.
Rheological measurements are quite relevant in the food industry as a tool for physical characterization of raw material prior to processing, for intermediate products during manufacturing, and for finished foods. There are several approaches to conduct these rheological characterizations, and the selected technique pretty much depend on the specific product and the functional characteristics in need to be analyzed. Several different types of equipments are available to scientists as a tool in food rheological studies leading to acceptable results in most design situations. This paper will focus on the review and discussion of some of the most relevant rheological tests of current interest to the food industry in selected examples, i.e. gels and emulsions.
Dynamic rheological testing has become a powerful and preferred approach for examining the structure and the fundamental properties of wheat flour doughs and proteins because of its characteristic and sensitive response to the structure variation of wheat flour doughs and proteins. In the present article, the dynamic rheological properties of wheat proteins and flour doughs were reviewed. Influences of various additives on the rheological properties of gluten proteins and flour doughs are illustrated and the component interactions are emphasized. Moreover, theoretical analyses concerning the relationship between rheological behavior and structure are summarized.
Several compounds presenting antioxidant properties have been tested in frying oils to delay thermal oxidation of the triglycerides containing unsaturated fatty acids. The present study was designed to evaluate, for the first time, the antioxidant and anti-polymerizing effects of addition of Exxenterol®, a denatured carob fiber very rich in non-extractable tannins, on olive oil (OO), sunflower oil (SO) and a homogeneous blend of both oils. Exxenterol was added to the three oils in amounts of 50, 250, 500 and 1000 mg/kg oil before heating. After 36 h of heating at 180 °C, there was a large and relevant increase of the polar material and the polymer contents, but tocopherol decreased to non-detectable levels in all three oils. Polar content, polymer and thermal oxidation formation (p ≤0.004) and tocopherol degradation (p ≤0.022) were significantly and dose-dependently inhibited by Exxenterol. Both polar material and polymer formation were inhibited (at least by 44%) in OO and SO and at least by 27% in the oil blend when 1000 mg/kg oil of this product was added. Small but detectable amounts of tocopherol were found in the oil blend containing 50 mg Exxenterol/kg. The results clearly show that this non-extractable tannin-rich fiber can be successfully employed as an additive to prolong oil shelf life at frying temperature.
Although the fruit of the carob tree (Ceratonia siliqua L. Fabaceae) is nutritious and widely available in Turkey, especially in West and South Anatolia, much remains to be learned about its nutrient composition. The main goal of our study was to determine if there are differences in the content of certain nutrients in commercially-prepared carob flour (CPCP) and domestic or home-prepared carob powder (HPCP). Sucrose was the main sugar in CPCP and HPCP. Total protein was 40% lower in CPCP than HPCP due mainly to decreases in the content of several essential amino acids. However, except for lysine in CPCP, HPCP and CPCP compared favourably to a WHO protein standard. There were large differences in terms of their content of the two essential fatty acids, linoleic and alpha-linolenic acid, and the linoleic acid/alpha-linolenic acid ratio was 3.6 for CPCP, and 6.1 for HPCP. Manganese and iron were 2.5-fold higher in HPCP than CPCP. This study demonstrates that carob flour prepared in either the household or industrially is a good source of many, but not all essential nutrients, and that commercial processing of carob fruit into flour seems to affect its content of several important nutrients.
The purpose of this study was to examine the antioxidant properties of water and 80% methanolic extracts of cereal grains and their different morphological fractions. Wheat (Triticum aestivum L.) cv. Almari and cv. Henika, barley (Hordeum vulgare L.) cv. Gregor and cv. Mobek, rye (Secale cereale L.) cv. Dańkowskie Zlote, oat (Avena sativa L.) cv. Slawko and buckwheat (Fagopyrum esculentum Moench) cv. Kora were used. PC (L-alpha-phosphatidylcholine) liposome system and spectrophotometric assay of total antioxidant activity (TAA) were used to evaluate the antioxidative activity of extracts. Among the water extracts, only the one prepared from buckwheat exhibited antioxidant activity at the concentration analyzed. The following hierarchy of antioxidant activity was provided for 80% methanolic extracts originated from whole grain: buckwheat > barley > oat > wheat congruent with rye. The antioxidant activity was observed in extract prepared from separated parts of buckwheat and barley. In respect to hulls, the antioxidant hierarchy was as follows: buckwheat > oat > barley. The correlation coefficient between total phenolic compounds and total antioxidative activity of the extracts was -0.35 for water extracts and 0.96, 0.99, 0.80, and 0.99 for 80% methanolic extracts originated from whole grains, hulls, pericarb with testa fractions and endosperm with embryo fractions, respectively.
Although it is already known that carob fibre contains several classes of polyphenolic substances, a comprehensive analysis of these has not been conducted to date. Therefore, the major polyphenolic compounds were extracted with organic solvents, and, following fractionation by normal-phase column chromatography on silicic acid, their structures were elucidated by liquid-chromatography electrospray-ionisation mass spectrometry (LC-ESI), nano-electrospray-ionisation mass spectrometry (ESI-MS), and gas-chromatography mass spectrometry (GC-MS). In addition, complete 1H and 13C NMR assignments were obtained for the isolated gallotannins 1,6-di-, 1,2,6-tri- and 1,2,3,6-tetra-O-galloyl-beta-D-glucose. Carob fibre was found to contain a rich variety of phenolic antioxidants. A total of 24 polyphenol compounds were identified with a yield of 3.94 g/kg (dry weight). The profile was dominated by gallic acid in various forms: free gallic acid (42% of polyphenols by weight), gallotannins (29%), and methyl gallate (1%), while simple phenols, mainly cinnamic acid, made up about 2% of the total. Flavonoids represented 26% of the polyphenols, and the major components were identified as the glycosides myricetin- and quercetin-3-O-alpha-L-rhamnoside (ca. 9% and 10%, respectively). These data indicate that carob fibre is rich in both amount and variety of phenolic antioxidant substances, and its inclusion in the diet may have chemopreventive properties.
Content of some nutrients in new black oat strains
- A Ciołek
- B Makarski
- E Makarska
- A Zadura
Ciołek, A., Makarski, B., Makarska, E., Zadura, A., 2007. Content of some nutrients in new black oat strains. Journal of Elementology 12 (4), 251–259.