No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Effect of salt solutions applied during wheat conditioning on lipase activity and lipid stability of whole wheat flour
Abstract
Lipolytic activity in whole wheat flour (WWF) is largely responsible for the loss in baking quality during storage. Metal ions affect the activity of seed lipases; however, no previous studies have applied this information to WWF in a way that reduces lipase activity, is practical for commercial manufacture, and uses common food ingredients. NaCl, KCl, Ca-propionate, or FeNa-ethylenediaminetetraacetic acid (FeNa-EDTA) were applied to hard red winter (HRW) and hard white spring (HWS) wheats during conditioning as aqueous solutions at concentrations that would be acceptable in baked goods. Salts affected lipase activity to different degrees depending on the type of wheat used. Inhibition was greater in HRW compared with HWS WWF, probably due to higher lipase activity in HRW wheat. In HRW WWF, 1% NaCl (flour weight) reduced hydrolytic and oxidative rancidity and resulted in higher loaf volume and lower firmness than untreated WWF after 24weeks of storage.
... The activities of lipases and esterases were reported to be 3-500 U kg −1 and 700-1000 U kg −1 respectively. [8][9][10] Even under flour storage conditions (10-14% moisture content), lipase keeps 50% of its maximum activity. The shelf life of whole-grain flour is only 3-9 months, which is less than half of the refined flour (9-15 months). ...
... The limited shelf life of whole-grain flour, especially as raw material, potentially leads to food lost and food waste. Attempts have been made to deactivate wheat lipases and other esterases through thermal treatment, 11,12 application of salt solution, 9 and irradiation. 13 These methods, however, not only are energy consuming but may also decrease the nutritional value of the products. ...
... 28 Apart from the pnitrophenyl substrates, several other studies reported wheat lipase activities using olive oil as substrate. [8][9][10] The activities ranged from 3 to 59 U kg −1 at a similar pH and temperature to our study, which is also in line with our results. ...
BACKGROUND
Whole‐grain wheat flour is facing the quality challenge of lipid rancidity, which decreases its nutritional, sensory, and technological properties. One of the major causes of lipid rancidity is endogenous esterases and lipases. This study evaluated 66 European wheat varieties grown at a single site over three years (2014, 2015, and 2016).
RESULTS
The 66 wheat varieties showed up to threefold variance on esterase and lipase activities. Wheat varieties that are suitable for lipid‐stable whole‐grain products (‘Julius’, ‘Lona’, and ‘Banquet’) were selected according to their consistently low esterase and lipase activities. The 3‐year mean‐based broad‐sense heritability of esterase and lipase was 0.75 and 0.44 respectively.
CONCLUSIONS
The findings indicate great genetic dependence of both esterase and lipase activities in wheat. The moderate to high heritability brings a new prospect of breeding selection of low‐lipase‐activity wheat for stable whole‐grain products. This result will improve the use of wheat as raw material, benefit cultivation selection, and provide consumers with better quality products. © 2020 Society of Chemical Industry
... Specifically, enhanced loaf volume and softness were observed. The enzymes belonging to the group of lipases were shown to increase loaf volume [8,9] and softness [8,10,11] as well as stickiness [12] in wheat bread. A similar effect was also observed in rice-based gluten-free bread [13]. ...
... Specifically, enhanced loaf volume and softness were observed. The enzymes belonging to the group of lipases were shown to increase loaf volume [8,9] and softness [8,10,11] as well as stickiness [12] in wheat bread. A similar effect was also observed in rice-based gluten-free bread [13]. ...
... Nonetheless, development of off-odour and off-flavour was determined in whole wheat bread upon storage as a consequence of its endogenous lipases [8] thus raising stability concerns for bread treated with exogenous lipases. Generally speaking, bread flavour is subject to negative changes upon storage, regardless of the type of enzymes present and/ or added. ...
In this study, lipase Lipopan® Xtra BG (Lipopan) was tested at different doses, measuring its effect on sensory and textural quality of a composite wheat–cassava bread across a 7-day storage. Lipopan addition at all doses tested (15, 25, 60 ppm) significantly increased loaf volume by 20–25%, crumb softness and elasticity, as observed by instrumental and sensory analyses. Multispectral imaging (MSI) determined higher porosity and pore size at 15 and 25 ppm Lipopan thus depicting increased gas retention which was attributed to enhanced gluten–starch plasticization due to the release of polar lipids. Addition of 60 ppm Lipopan generated cohesive crumb. Storage-induced crumb hardening observed in the control did not occur in the Lipopan-containing counterparts; this was attributed to enhanced interaction of the released lipids with amylose complexes which inhibited starch recrystallization. Nonetheless, higher intensities of stale and dusty aroma and less of fresh baked flavour were perceived by sensory assessors in the lipase-containing bread after 7 days compared to lipase-containing bread after 1-day storage. In conclusion, Lipopan increased loaf volume significantly and after the 7-day storage, delayed staling and developed off-odour.
... Lipolytic enzymes play a vital role in the functional changes in whole wheat (Triticum aestivium L.) flour during storage (Doblado-Maldonado et al 2013). Lipase (triacylglycerol hydrolase, EC 3.1.1.3) ...
... Since loss of flour quality seems to be a function mostly of liberation and subsequent oxidation of unsaturated long-chain fatty acids, it would seem that true lipase activity would be more relevant to wheat quality than general esterase activity. Previous studies have based conclusions on the lipase activity measured by one substrate (Doblado-Maldonado et al 2013;De Almeida et al 2014). However, as the activity could differ among substrates it is relevant to compare lipase activity measurements among substrates. ...
... Lipase activity using olive oil as the substrate was determined as previously described (Doblado-Maldonado et al. 2013). Briefly, wheat grains were milled using a cyclone mill (UDY, Fort Collins, CO USA) equipped with a 1 mm screen. ...
The numerous enzymes present in the bran and germ fractions of a wheat kernel initiate many chemical changes that affect the compositional and functional properties of whole wheat flour. This dissertation was focused on enzyme activities and compositional properties of whole wheat flour in different applications. In the first study, lipolytic activity, which leads to rancidity during storage of wheat, was affected by environment, fungicide application, disease resistance of cultivars, and the substrate being used in the assay. Subsequently, steaming of grains for 90 s before milling was found to reduce lipolytic activities and accumulation of free fatty acids during storage and reduce oxidation once the flour was made into a dough without affecting starch and gluten properties. In another study, germination of wheat increased lipolytic activities and affected several compositional and functional properties mainly due to germination time rather than drying temperature. A small proportion of germinated flour added to a whole wheat bread formulation was found to improve bread quality except when the flour from extensive germination or higher inclusion percentage was used. Next, a sensory-driven approach was taken to estimate the shelf-life of whole wheat flour. The estimated shelf life of whole wheat flour stored at 35 °C ranged from 8-11 months and was dependent on the wheat cultivar. In a comparative study between historical and modern wheat cultivars, minimal changes in compositional properties (except for tryptophan) were found due to year of introduction. Finally, evidence of the asparaginase activity in wheat kernels and their possible genotypic variation was discovered. In conclusion, the enzymatic activities and compositional properties of whole wheat flour were dependent on the genotype, environment, their interactions, and different processing methods. Advisor: Devin J. Rose
... Lipolytic enzymes play a vital role in the functional changes in whole wheat (Triticum aestivum L.) flour during storage (Doblado-Maldonado et al. 2013). Lipase (triacylglycerol hydrolase, EC 3.1.1.3) ...
... Because loss of flour quality seems to be a function mostly of liberation and subsequent oxidation of unsaturated long-chain fatty acids, it would seem that true lipase activity would be more relevant to wheat quality than general esterase activity. Previous studies have based conclusions on the lipase activity measured by one substrate (Doblado-Maldonado et al. 2013;De Almeida et al. 2014). However, because the activity could differ among substrates it is relevant to compare lipase activity measurements among substrates. ...
... Lipase Activity Using Olive Oil as the Substrate. Lipase activity using olive oil as the substrate was determined as previously described (Doblado-Maldonado et al. 2013). Briefly, wheat grains were milled with a cyclone mill (UDY, Fort Collins, CO, U.S.A.) equipped with a 1 mm screen. ...
... Preston (1989) suggested that the molar concentrations (0.5-10) of different salts (Cl -, Br -, I -, SCN -, and ClO -4 ) reduced water absorption of dough. Recently, Doblado-Maldonado, Armdt, and Rose (2013) used brine solution to temper two varieties of hard white spring and hard red winter wheat grains, which were conditioned with 1% brine solution and water containing metal ions with different concentrations. They investigated the effects of this treatment on lipase activity and the effectiveness of this treatment on the volume of bread and rheological properties of dough. ...
... ). Water may exist in masses or in the form of small droplets in protein network or surrounding starch granules. In such a compact structure, salts with gluten and starch tend to absorb water and, therefore, change the water dispersion in dough structure(Doblado-Maldonado et al., 2013;Quilez & Salas-Salvado, 2012). According toBonfil and Posner (2012) by the addition of salt at the level of 5% to wheat during conditioning, the area under the curve is increased significantly and the wheat flour protein is improved. ...
Wheat conditioning plays a key role on the final quality of flour and consequently it dough and bread. Three levels of brine solution (0.5, 1, and 1.5%) were added to wheat and the grains were conditioned for 24 hr at room temperature. Results suggested that lipase activity was decreased significantly in proportion to salt content of the brine, which may have a positive impact on dough quality. Salt had a significant negative effect (p < .05) on amylase activity. A significant increase was evidenced for lipoxygenase activity in all salt percentages. Use of brine solution, while leading to reduced water absorption and degree of dough softening, increases dough development time and dough resistance to extension. The ratio of dough resistance to extension to extensibility increased along with energy during fermentation. The changes indicated that conditioning of wheat by brine solution may improve flour strength and dough ability to keep the gases produced during fermentation.
Practical applications
Wheat enzymes, for example, amylase, lipase, and lipooxygenase, have been a matter of interest as they may have positive or detrimental effects on the flour color, dough rheological properties, and bread quality particularly its porosity and volume. During conditioning of the grain, most of the enzymes are activated; however, there are reports that their activity might be affected by the presence of salt. This study was performed to monitor possible beneficiary wheat enzymes' activation during conditioning. The information will be useful for millers in terms of color of the flour and bakers who are involved with the dough and its rheological properties.
... Furthermore, lipid oxidation does not require oxygen, enzymes present in the germ cause hydrolytic rancidity (Doblado-Maldonado et al. 2012). Treatment of hard red winter wheat with 1% NaCl (flour weight) was found to be effective in preventing hydrolytic and oxidative rancidity and reducing lipid breakdown of flour during 24 weeks of storage (Doblado-Maldonado et al. 2013). ...
Cereals, including wheat, play a crucial role in human nutrition, providing a significant proportion of dietary energy and essential nutrients such as proteins, vitamins, minerals, and dietary fiber. Wheat, in particular, is one of the most important staple crops consumed globally, accounting for a significant portion of the world’s food supply. Wheat kernels are composed of three main parts, bran, germ, and endosperm, which are milled into flour used to make various food products, including bread, pasta, cakes, and cookies. Wheat has a significant amount of dietary fiber, proteins, minerals, vitamins, and phytochemicals. The present review represents the impact of various chemical, physical and biological treatments to improve the overall quality and storage stability of wheat grain, flour and resultant products. This review article highlights the impact of these various treatments on the physicochemical, nutritional, and functional characteristics of wheat-based products, as well as their storage stability. By selecting appropriate processing techniques, food manufacturers can develop final products with desirable characteristics and enhanced storage stability, providing consumers with nutritious and safe food products.
... In addition, lipid oxidation starts with hydrolytic rancidity in presence of enzymes, and oxygen is not required in this process (Doblado-Maldonado et al., 2012). Additionally, throughout 24 weeks of storage, the oxidative and hydrolytic rancidity of the flour was prevented by conditioning hard red winter wheat with 1% NaCl (flour weight), which reduced lipid degradation (Doblado-Maldonado et al., 2013). The steam treatment (180 s) and superheated steam (155-170°C for 10-90 s and 190 °C for 5 s) treatment of wheat grains before milling have also been mentioned to significantly inactivate lipase, lipoxygenase, polyphenol oxidase, endoxylanase, peroxidase, and α-amylase without gelatinising starch (de Almeida et al., 2014;Jia et al., 2021;Guo et al., 2020;Poudel and Rose, 2018). ...
Wheat is the most widely grown crop in temperate countries, and it is consumed as a human food and livestock feed. Whole wheat is composed of bran, germ, and endosperm. The wheat milling separates the wheat grain into germ, bran, and endosperm, and the efficiency of separation depends on the milling process. Various characteristics of wheat grain, namely, shape, size, texture, density, and chemical content, are known to affect the milling process. Different milling methods such as stone milling, roller milling, jet milling, ultrafine milling, and hammer milling are being employed for wheat milling. During conventional milling, only carbohydrate-rich endosperm is retained, and other important nutrients and phytochemicals are lost with the removal of bran and germ. The resulting refined wheat flour is used for the preparation of bakery and other food products, which are liked by the consumers due to taste, texture, and appearance. But the consumption of refined wheat flour is known to be associated with the widespread prevalence of digestive disturbances and nutritional disorders. Therefore, milling is considered a crucial process that influences the nutritional quality of wheat-derived food products. Consumers nowadays demand whole wheat grain products because of health benefits associated with their consumption. The growing demand for whole-wheat flour (WWF) has triggered researchers to explore the impact of different types of milling and processing technologies on the nutritional quality of resultant wheat flour. Despite the increased demand for WWF, proper milling processes for its production are yet to be established. Thus, in this chapter, an attempt is made to discuss in detail different milling technologies and their effect on the nutritional quality of wheat flour. Further, challenges and strategies to produce wheat flour for the development of specific end products with desired nutritional and functional properties will be discussed.
... In addition, the values fluctuated but remained stable in each step during the preparation of the dried noodles, indicating that the processes, including hydration, sheeting, and drying did not influence the lipase activity. Lipase activity varies with different wheat varieties (Doblado-Maldonado et al., 2013). In addition, the relatively high lipase activity might have been due to the low refinery level of the white flour (ash content 0.74 ± 0.02%), which exhibited a high residue of bran fractions in the flour. ...
This study investigated the changes of lipids during the industrial preparation of noodle dough and dried noodles, including the hydration, sheeting, and drying processes. The results showed that industrial processing markedly influenced the stability of lipids during the preparation of dried noodles. The contents of total free fatty acids, polyunsaturated fatty acids, and free lipids were reduced, while peroxide values increased during the hydration and sheeting processes, showing the instability of lipids. The increase in lipid oxidation may have been due to the activation of lipoxygenase. Although its activity declined by 45.7% in the hydration process compared to that of the native wheat flour (198.5 ± 20.4 U/g/min), the residue activity should have been high enough to oxidize lipids. Interestingly, lipase activity remained relatively stable. In addition, an obvious increase of carbon‐centered free radicals was observed during the entire processing. In conclusion, the industrial processing, especially the hydration process, markedly changed the lipid profile and promoted lipid oxidation during the preparation of dried noodles.
Practical Application
The present study showed the positive relationship between endogenous lipid degrading enzymes and the degradation of lipids and elucidated the role of industrial processing on lipid stability in noodle dough and dried noodles. The results of the present study will also help us to understand more about the sensory quality of dried noodles during preparation, as well as to develop high quality of wheat‐based food products.
... Bergonio et al. 2016;Ding et al. 2015;Lakkakula et al. 2004;Lavanya et al. 2019;Rocha-Villarreal et al. 2018); low pressure cold plasma treatment; extrusion cooking (Guevara-Guerrero et al. 2019); gamma irradiation(Nor et al. 2014); pulsed electric fields(Qian et al. 2014) and chemical methods such as hydrochloric acid treatment(Akhter et al. 2015); salt treatment(Doblado-Maldonado et al. 2013); addition of antioxidants(Atapattu 2013;Morais et al. 2011); ozone treatment(Zhu 2018); addition of enzyme inhibitors(Bhardwaj et al. 2001;Korneeva et al. 2008;Macedo 2010) etc. are applied on the Expression analysis of selected lipase genes among different tissues. Q-PCR analysis of selected four lipases in root, shoot, flag leaf and different stages of developing seeds. ...
Key message
Among the 113 lipases present in rice genome, bran and endosperm-specific lipases were identified and lipase activity for one of the selected lipase gene is demonstrated in yeast.
Abstract
Rice bran is nutritionally superior than endosperm as it has major reservoirs of various minerals, vitamins, essential mineral oils and other bioactive compounds, however it is often under-utilized as a food product due to bran instability after milling. Various hydrolytic enzymes, such as lipases, present in bran causes degradation of the lipids present and are responsible for the bran instability. Here, in this study, we have systematically analyzed the 113 lipase genes present in rice genome, and identified 21 seed-specific lipases. By analyzing the expression of these genes in different seed tissues during seed development, we have identified three bran-specific and three endosperm-specific lipases, and one lipase which expresses in both bran and endosperm tissues. Further analysis of these genes during seed maturation and seed germination revealed that their expression increases during seed maturation and decreases during seed germination. Finally, we have shown the lipase activity for one of the selected genes, LOC_Os05g30900, in heterologous system yeast. The bran-specific lipases identified in this study would be very valuable for engineering designer rice varieties having increased bran stability in post-milling.
... Hence, addition of a pinch of NaCl in the flour has been reported to inhibit the lipase/ lipoxygenase activities, and in turn improves the flour shelf-life. One percent NaCl has been observed to inhibit the lipase activity by 75% in wheat flour (Doblado-Maldonado et al., 2013). Even parboiling has been observed in destroying lipase activity in rice bran (Sharif et al., 2014). ...
Pearl millet is considered as ‘nutri-cereal’ because of high nutrient density of the seeds. The grain has limited use because of low keeping quality of the flour due to the activities of rancidity causing enzymes like lipase, lox, pox and PPO. Among all the enzymes, lipase is most notorious because of its robust nature and high activity under different conditions. we have identified 2180 putative transcripts showing homology with different variants of lipase precursor through transcriptome data mining (NCBI BioProject acc. no. PRJNA625418). Lipase plays dual role of facilitating the germination of seeds and deteriorating the quality of the pearl millet flour through hydrolytic rancidity. Different physiochemical methods like heat treatment, micro oven, hydrothermal, etc. have been developed to inhibit lipase activity in pearl millet flour. There is further need to develop improved processing technologies to inhibit the hydrolytic and oxidative rancidity in the floor with enhanced shelf-life.
... Volatile compounds were mainly produced through hydrolysis and oxidation of lipids during storage, as well as degradation of proteins, carbohydrates and amino acids (Liu, Li, Chen, & Yong, 2017). Lipid broken down quickly by the hydrolysis of lipase (LIP) results in the release of free fatty acids at the early stage of storage, and free fatty acids are oxidized by lipoxygenase (LOX) or autoxidation to form fatty acid hydroperoxides which are followed by further oxidative degradation by peroxidase (POD) or non-enzymatic reaction to generate off-flavor volatile compounds (Doblado-Maldonado, Arndt, & Rose, 2013;Suzuki, Honda, Mukasa, & Kim, 2005). The LIP and POD activities in buckwheat flour are important for the flavor generation of buckwheat noodles (Suzuki et al., 2010). ...
Buckwheat freshness plays a key role in the qualities of noodles. The present study focuses on the protective effects of superheated steam (SS) processing on the quality deterioration of noodles made from stored buckwheat grains. Changes of the volatile compounds, lipid degrading enzymes, pasting properties, farinograph characteristics of buckwheat grains, together with the cooking qualities and texture profiles of buckwheat noodles were investigated. Results suggested that 3-methyl-butyraldehyde and hexanal were the markers of lipid oxidation and flavor change of buckwheat grains during storage. SS treatment inactivated lipase, lipoxygenase and peroxidase and affected the generation of off-flavor volatile compounds of buckwheat grains, thus retarded the flavor deterioration of buckwheat noodles made from stored buckwheat. Storage significantly (P < 0.05) decreased the pasting viscosities, water absorption and development time of buckwheat dough. SS treatment maintained the pasting properties of starch stable and enhanced the elasticity and strength of the dough, leading to the improvement of cooking qualities and texture profiles of buckwheat noodles. Therefore, SS processing was an effective way to improve the qualities of buckwheat noodles by stabilizing buckwheat grains.
... Improving storage property of wheat bran is beneficial to wheat bran and whole wheat flour products development. Previous studies were elucidated the effects of different treatments for stabilization of wheat bran, such as microwave (Xu et al., 2013), hot air treatment (Rose et al., 2008) salt solutions addition (Doblado-Maldonado et al., 2013) and superheated steam treatment (Hu et al., 2018). However, these treatments existed the problems, such as chemical residue or energy consuming, limited the application. ...
Steam explosion (SE) was exploited for stabilizing wheat bran (WB), and its effects on nutrients retention of WB were investigated. Result showed that SE could effectively inactivate lipase and peroxidase of WB at 0.8 MPa (170 °C) for 5 min while lipid and protein were not loss. Total flavonoids, phenolics contents, soluble dietary fibre content and DPPH radical scavenging activity in WB after SE increased by 198%, 83%, 27% and 21% respectively compared with those after conventional thermal sterilization (0.1 MPa (121 °C) for 20 min), while fatty acid value and peroxide value and insoluble dietary fibre content deceased by 21%, 75% and 24%, respectively. SE inhibited hydrolysis rancidity of wheat bran and reconstituted whole wheat flour (wholemeal) in the accelerated storage test. Therefore, SE may be a new efficient technology that could stabilize cereal bran and further promote its products development.
... FFA, conjugated dienes, peroxide value, and hexanal were measured on stored flour. FFA and conjugated dienes were measured as described (Doblado-Maldonado, Arndt, & Rose, 2013). Peroxide value was measured as described (Wrolstad et al., 2005, chap. ...
The effects of steaming wheat kernels on lipolytic degradation of resulting whole flour was studied by quantifying enzyme activities and lipid degradation products during storage. Lipase, lipoxygenase, polyphenol oxidase, and peroxidase activities were decreased by up to 81%, 63%, 22%, and 34%, respectively, as the time of steaming increased up to 90 s. Steaming had no effect on starch and gluten properties. Upon storage free fatty acids decreased with respect to time of steaming. Time of steaming did not affect lipid oxidation in flour; however, total carbonyls produced in dough made from stored flour were decreased with the increase in steaming duration. Thus, steaming wheat kernels prior to milling reduced lipase activity and consequently hydrolytic rancidity during storage without affecting starch and gluten fractions. Steam treatment did not affect oxidative rancidity in flour during storage, but did reduce oxidation once the flour was made into a dough.
... For example, Munshi et al. 13 found that lipid rancidity of RB could be inhibited by spraying solutions of FeCl 3 or NiCl 2 over the bran during storage. Doblado-Maldonado et al. 14 reported that replaced tempering water by NaCl, KCl and FeNaEDTA solutions prior to wheat milling could reduce the lipid rancidity of whole wheat flour during storage. Based on the higher effectiveness of wet heating compared to dry heating for RB stabilization, metal salt solutions might be able to replace water to moistening the RB and exert the synergy effect for inactivation of lipase during RB stabilization using dielectric heating. ...
Dielectric heating including microwave (MW) and radio frequency (RF) energy has been regarded as alternative thermal treatments for food processing. To develop effective rice bran (RB) stabilization treatments based on RF and MW heating, dielectric properties (DPs) with dielectric constant (ε') and loss factor (ε″) of RB samples at frequencies (10-3000 MHz), temperatures (25-100 °C), moisture content (MC, 10.36-24.69% w.b.) and three metal salt levels (0.05-2.00%) were determined by an open-ended coaxial probe and impedance analyzer. Results indicated that both ε' and ε″ of RB samples increased with increasing temperature and MC. The increase rate was greater at higher temperature and moisture levels than at lower levels, especially at frequencies lower than 300 MHz. Cubic order models were developed to best fit the relationship between DPs of RB samples and temperature/MC at five frequencies with R2greater than 0.994. Both ε″ and RF heating rate of RB samples increased significantly with added NaCl (2%), KCl (1%) and Na6O18P6(2%). The obtained data are useful in developing computer models and simulating dielectric heating for RB stabilization and may also provide theoretical basis for synergistic stabilization of RB under combined dielectric heating with metal salts.
... For many foods, it is desired to have low residual enzyme activity to stabilize the quality of the product. Examples where high residual enzyme activity detrimentally affects food quality are enzymatic browning in vegetables and fruits, starch degradation in grain products, and enzymatic reactions causing rancidity and off-flavors, etc. (Doblado-Maldonado, Arndt, & Rose, 2013;Kalita, Sarma, & Srivastava, 2017;Lante, Tinello, & Nicoletto, 2016;Luyben, Liou, & Bruin, 1982). In some other cases, one strives to retain high residual activity of the enzyme after processing, for example when the enzyme is used as a food ingredient or a processing-aid to achieve a specific transformation (Guidini, Fischer, Resende, De Cardoso, & Ribeiro, 2011;Ramos & Malcata, 2011;Wu, Dong, Lu, & Li, 2010). ...
... HPH did not influence either the fatty acid composition or the free acidity of EYC, in agreement with Pereda et al. [22] and Rodriguez et al. [23]. The decreased free acidity observed in EYC containing the highest NaCl concentration could be accounted to changes in lipase activity, already reported in flours having 1% NaCl concentration [24]. ...
... AACC International, 2013) and subsequently collecting all milling fractions. The nonflour milling fractions (bran, shorts) are then re-milled using a conical or hammer mill and then recombined with the straightgrade flour (Rose et al., 2008; Guttieri et al., 2011; Sanz-Penella et al., 2012; Sapirstein et al., 2012; Doblado-Maldonado et al., 2013). The disparity among milling methods in the literature makes comparing results among studies difficult, since particle size distribution has such an important influence on flour functionality (Noort et al., 2010). ...
The objective of this study was to produce wholegrain wheat flour on a laboratory-scale with particle size distributions similar to commercially-milled samples without re-milling the bran. The moisture contents of four hard winter wheat cultivars were adjusted to 7.29–7.98% (by drying), 9.00–10.6% (“as is”), and 15.6% (by tempering) prior to milling into wholegrain flour. The moisture treatments appeared to affect the partitioning of wholegrain flour particles into each of three categories: fine (<600 μm), medium (600–849 μm) and coarse (≥850 μm). When the distributions of particles were grouped into these categories, wholegrain flours made from dried and “as is” wheat fell within the values for commercial wholegrain flours, while that from tempered wheat contained more coarse particles than even the coarsest commercial wholegrain flour. Loaf volumes and crumb firmness were not significantly different between bread made from wholegrain flour that had been produced from dried or “as is” wheat, but loaf volume was significantly lower and bread crumb firmness was significantly higher when wholegrain flour from tempered wheat was used. These results show that wheat may be milled without tempering to produce wholegrain flour with particle size similar to some commercially-milled flours without needing to re-grind the bran.
Despite its nutritional superiority, the utilization of pearl millet grain and flour is limited
to few specific pockets and regions all-round the world due to the poor keeping quality of the
grain and flour and development of off odour during storage. The poor
keeping quality of pearl millet grain and flour is due to the oxidative and hydrolytic rancidity
caused by Lipase (LA), Lipoxygenase (LOX), Free fatty acids (FFA), Peroxide value (PV),
Acid value (AV), Water activity (aw). So, the innovation of novel technologies in storage of
millets i.e., especially for pearl millet is necessary.
Background and Objectives
Breeding of intermediate wheatgrass ( Thinopyrum intermedium , IWG) culminated in the release of a commercial cultivar (MN‐Clearwater) with attractive environmental and nutritional benefits. Determining the impacts of ambient storage and common postharvest processing on the stability of IWG flour is essential to promote it as a food ingredient. Accordingly, MN‐Clearwater and two other potential cultivars, selected for their unique chemical composition, were subjected to extrusion and germination followed by 8 months of storage. Antioxidants, lipase and lipoxygenase activity, free fatty acid (FFA), peroxide value (PV), and volatile odor compounds (VOC) were analyzed at different timepoints.
Findings
While germination caused a significant increase in lipase activity (~threefold in MN‐Clearwater), extrusion resulted in complete lipase degradation. Additionally, lipase activity was more consequential to hydrolytic rancidity than fat content. Regardless, results indicated that the endogenously abundant antioxidants can combat rancidity facilitated by enzymes and autoxidation as evidenced by significant losses in carotenoids between 3 and 6 months of storage (with 70%–80% reduction after 6 months of storage), when steep increases in FFA (up to 40% oleic acid/100 g fat), PV (two‐fourfolds increase after 6 months of storage), and VOC (hexanal and 2‐pentyl‐furan) occurred.
Significance and Novelty
The findings of this work serve as an impetus for IWG breeding advancements since enzymes and antioxidants can be traits that breeders may consider when selecting cultivar candidates. Results can be also utilized to understand the impact of postharvest processing of the grain on the storage stability of its flour.
During the storage of wheat grains and flours, a natural deterioration occurs due to aging over time, which is accelerated by adverse conditions of temperature and humidity that cause the growth of fungi. The local climates and infrastructure available for storage affect the preservation and duration of the safe storage time. Wheat lipids are a minor component, whose level and composition are decisive in the quality properties of wheat final products. Lipids are easily degraded, which is the main cause of quality loss. The enzymatic degradation of lipids is carried out by the activation of endogenous and/or fungal enzymatic activities, which produces hydrolytic and oxidative rancidity. Fusarium, Aspergillus, Penicillium and Alternaria are the most frequent genera found in infected grains. Wheat infection by Fusarium spp. is associated with considerable economic losses in crops throughout the world. The volatile compounds produced by oxidative rancidity are the main indicators of deterioration. Lipid rancidity must be monitored periodically using a combination of different analytical methods, ranging from traditional to modern alternative techniques of varied scope. Sensitivity to lipid deterioration varies with the wheat cultivar genotype, thus the selection of cultivars with better stability allows to obtain better quality products. In addition, a large proportion of the harvested wheat is usually stored for a long time until use, so achieving suitable environmental conditions and applying control measures prevent quality loss. This review updates the knowledge about wheat lipids, the importance of preserving their integrity during storage, presenting different monitoring alternatives to detect their rancidity, which would allow better decision-making.
Suitable conditions of temperature and humidity are required to maintain wheat grains quality, but during processing and storage, the grains can be exposed to adverse environmental conditions and presence of infectious fungi. Fusarium graminearum, the main causal agent of Fusarium head blight on wheat, affects crop yields and grain quality by alteration of their biochemical components and mycotoxin contamination, which reduces the possibilities of wheat end use and compromises food safety. Lipid degradation by hydrolytic, oxidative and microbial deterioration is the predominant cause of the loss of sensory acceptability, nutritional value and baking quality. The aim of this research was to determine the influence of adverse environmental conditions –as the increasing moisture– on lipid patterns of whole wheat flours contaminated with F. graminearum in relation to the infection degree. In vitro cultures of F. graminearum were carried out on wheat grains under different degrees of relative humidity (11, 50, 75 and 100%) throughout 45 days of incubation at 28 °C. The fungal biomass measured by q-PCR increased proportionally with the humidity. A decrease in the signals of saturated (palmitic and estearic) and unsaturated (oleic, linoleic and linolenic) fatty acids, analyzed as fatty acid methyl esters (FAMEs) by GC-MS, was observed in relation with the humidity and infection degree. The degradation rate of the lipids was high during the first 15 days of incubation, reaching the fatty acids content, values around 20-40% of those found in the control. From that moment on, the rate of degradation was slower or even null. It was observed that in all treatments, the linolenic acid reached the highest degradation ratio in comparison with the other fatty acids, which may be caused by the action of lipoxygenases. The lipase activity and the content of deoxynivalenol were also determinate on the flours. The lipase activity increased until day 25 of incubation reaching twice the initial value. The deoxynivalenol content also increased along incubation while fatty acids decreased. Our results demonstrated that the magnitude in the signal of fatty acids in whole wheat flours varied in relation to the degree of humidity and fungal infection of the grains from which they were obtained. Otherwise, lipids and their oxidation products are related with the pathogenesis and production of mycotoxins. These observations highlights the importance of an adequate manipulation of wheat grains on the processing chain to prevent quality changes and mycotoxins contamination.
Superheated steam (SS) was used to inactivate peroxidase and lipolytic enzymes of wheat bran (WB) in this study. Meanwhile, the effects of SS on nutritional attributes of WB were also evaluated. Compared with conventional hot air (HA) treatment (16 min), SS processing could inactivate enzymes of WB within a much shorter time (7 min). SS processing did not cause the loss of non-starch nutrients (lipid, protein, ash and dietary fiber) or promote the oxidation of lipids in WB. Superheated steam-stabilized wheat bran (SS-WB) also showed comparable antioxidant activities to that of native WB. However, compared with hot air-stabilized wheat bran (HA-WB), SS-WB exhibited a brighter color (L* value, 69.96 and 64.65, respectivly), higher extractable phenolic compounds contents (3736.7 and 2952.1 μg GAE/g WB d.b., respectivly) and stronger antioxidant activities (13.76 and 11.95 μmol Trolox equivalent/g WB d.b., respectivly) as well as lower peroxide value (1.27 and 1.81 meq O²/kg d.b., respectivly), higher unsaturated fatty acid contents (64.05% and 58.11%, respectivly) and sensory evaluation scores. Therefore, SS treatment should be a new efficient technology that could stabilize WB while maintain its nutritional attributes at the same time. The resultant SS-WB may be a potential alternative to native WB and HA-WB.
This paper provides an overview regarding the main aspects of seed lipases, such as the reactions catalyzed, physiological functions, specificities, sources and applications. Lipases are ubiquitous in nature and are produced by several plants, animals and microorganisms. These enzymes exhibit several very interesting features, such as low cost and easy purification, which make their commercial exploitation as industrial enzymes a potentially attractive alternative. The applications of lipases in food, detergents, oils and fats, medicines and fine chemistry, effluent treatment, biodiesel production and in the cellulose pulp industry, as well as the main sources of oilseed and cereal seed lipases, are reviewed.
Bread is widely considered to be the foodstuff that provides the most dietary salt to the diet. As such, it is one of the key public health targets for a salt reduction policy. In this respect, it has been shown that a reduction in the salt content of bread is possible, and an alternative approach involves partial replacement with other, mainly potassium-based salts, which also counteract the effects of sodium. This replacement should be undertaken on the basis of criteria that maintain the product's sensory profile, and it tends to be more successful in breads with more naturally flavorful taste. The present review was conducted to examine salt intake in Europe and the health problems associated with its excessive consumption; particular focus is placed on the salt content of bread and the effects of its possible reduction and/or correction. The beneficial effects of such changes are highlighted by way of a theoretical calculation in baguette-type wheat bread. European legislation in the field of nutrition and health claims allows the positive aspects of such salt reduction and replacement methods to be stated.
Kama flour is a traditional Estonian food, consisting of a newly milled powder mixture of roasted barley, rye, wheat and pea flour. For consumption it is normally mixed with sour milk and sweetened with sugar. In this study the aroma profile of Kama flour was studied. For the analysis, the solid-phase microextraction (SPME) method was optimized and used in combination with gas–chromatography/mass spectrometry (GC/MS) and GC–olfactometry (GCO), where the human nose is used as a sensitive and specific detector for odour-active compounds. For a positive identification of the aroma-active compounds, calculation of retention indices combined with the odour impression of pure reference compounds in a comparable concentration, and the mass spectrum under the same conditions as GC-O were used. The analysis of Kama flour headspace by GC/MS led to the detection of 89 compounds, of which 62 were found to have odour impression according to the literature. However, in total, 30 odour-active compounds were detected with GCO from which seven could not be detected under the same chromatographic conditions either by GC/MS or GC with FID. Most of the identified aroma compounds belonged to pyrazines coming from roasting process of Kama flour due to the Maillard reaction. Additionally, 2,3-butadedione, hexanal and 1-octen-3-one contributed to the aroma of Kama flour. Copyright © 2010 John Wiley & Sons, Ltd.
The effect of packaging materials on the physicochemical and rheological characteristics of iron-fortified wholemeal flour (WMF) during storage was determined. WMF was fortified with three fortificants, namely ferrous sulfate (30 ppm), ferrous sulfate + ethylenediamine tetraacetic acid (EDTA) (20 + 20 ppm) and elemental iron (60 ppm). Each flour was also fortified with 1.5 ppm folic acid. Moisture, flour acidity and peroxide value increased during storage, while protein and fat contents decreased. Highest conversion of Fe2+ into Fe(3+)was observed in flour fortified with ferrous sulfate (2.72%), followed by that fortified with ferrous sulfate + EDTA (1.49%) and elemental iron (1.06%). Water absorption and dough viscosity of iron-fortified flours increased during storage. The flour containing ferrous sulfate was most acceptable regarding sensory characteristics, followed by samples containing ferrous sulfate + EDTA. Fortified flours were more stable during storage than unfortified. Addition of EDTA increased the stability of flours and fortificants. The fortified flours stored in polypropylene bags proved more stable than those stored in the tin boxes.
Sodium iron ethylenediaminetetraacetic acetate (NaFeEDTA) is a promising iron fortificant for populations consuming high-phytate diets. It produces fewer organoleptic effects than other fortificants do, especially when the matrix of the food vehicle contains fat, and has a bioavailability two to four times higher than that of ferrous sulfate. This study investigated the effects of varying levels of NaFeEDTA (576-1152 mg kg(-1)) on the physicochemical and sensory characteristics of Petit Beurre biscuits.
There were no significant differences in pH, ash, moisture and breaking strength values among all formulae. The iron content (7.2-14.4 mg per 100 g) of the biscuits increased with increasing fortificant level. During a 60 day storage period the peroxide value increased in both fortified and non-fortified formulae, especially after 28 days. The addition of NaFeEDTA had a significant (P < 0.05) effect on the colour, texture and flavour of fortified biscuits.
Based on the range proposed for the use of NaFeEDTA as a fortification agent (10 mg iron and 67 mg EDTA per person per day), the results of this study reveal that 720 mg kg(-1) NaFeEDTA (9 mg iron per 100 g) is the optimum level for iron fortification in Petit Beurre biscuits.
Iron fortification of wheat flour is widely used as a strategy to combat iron deficiency.
To review recent efficacy studies and update the guidelines for the iron fortification of wheat flour.
Efficacy studies with a variety of iron-fortified foods were reviewed to determine the minimum daily amounts of additional iron that have been shown to meaningfully improve iron status in children, adolescents, and women of reproductive age. Recommendations were computed by determining the fortification levels needed to provide these additional quantities of iron each day in three different wheat flour consumption patterns. Current wheat flour iron fortification programs in 78 countries were evaluated.
When average daily consumption of low-extraction (< or = 0.8% ash) wheat flour is 150 to 300 g, it is recommended to add 20 ppm iron as NaFeEDTA, or 30 ppm as dried ferrous sulfate or ferrous fumarate. If sensory changes or cost limits the use of these compounds, electrolytic iron at 60 ppm is the second choice. Corresponding fortification levels were calculated for wheat flour intakes of < 150 g/day and > 300 g/day. Electrolytic iron is not recommended for flour intakes of < 150 g/day. Encapsulated ferrous sulfate or fumarate can be added at the same concentrations as the non-encapsulated compounds. For high-extraction wheat flour (> 0.8% ash), NaFeEDTA is the only iron compound recommended. Only nine national programs (Argentina, Chile, Egypt, Iran, Jordan, Lebanon, Syria, Turkmenistan, and Uruguay) were judged likely to have a significant positive impact on iron status if coverage is optimized. Most countries use non-recommended, low-bioavailability, atomized, reduced or hydrogen-reduced iron powders.
Most current iron fortification programs are likely to be ineffective. Legislation needs updating in many countries so that flour is fortified with adequate levels of the recommended iron compounds.
Enzymatic properties of a galactolipase (G–2) which has the highest activity in four galactolipases of rice bran were investigated. The molecular weight was estimated to be about 4 × 104 by gel filtration, and the Km value was 0.34 mm for monogalactosyldiacylglycerol. The enzyme was activated markedly by sodium deoxycholate and slightly by calcium ion, but inhibited by EDTA, Triton-X–100, sodium dodecylsulfate, NaCl and organic solvents. The enzyme lost more than 95% of its original activity when heated at 50°C for 10 min at pH 7.5. The enzyme catalyzed the hydrolysis of both galacto- and phospholipids. The relative hydrolysis rates decreased in the order of digalactosyldiacylglycerol > monogalactosylmonoacylglycerol > monogalactosyldiacylgiycerol > lysophosphatidylcholine > phosphatidylcholine. The enzyme catalyzed the hydrolysis of fatty acid ester bonds at both C − 1 and −2 positions of galactolipid. It is suggested that serine and cystine residues are important to the enzymic activity.
Whole wheat flour is increasingly popular as research continues to reveal the benefits of whole grains and the food industry offers more whole grain options for consumers. The purpose of this review is to address milling and shelf-life issues that are unique to whole wheat flour. No standard methods are available for whole wheat flour milling, resulting in very different bran particle sizes. Literature suggests that moderate bran particle size is the best for bread production, while small particle size is better for non-gluten applications. Shelf-life of whole wheat flour is shorter compared to white flour due to the presence of lipids and lipid-degrading enzymes. Lipolytic degradation leads to reduction in functionality, palatability and nutritional properties. Strategies to stabilize whole wheat flour have focused on controlling lipolytic enzyme activity and have marginally succeeded.
The purpose of this study was to determine the effectiveness of dry heat, steam, and microwave treatments in decreasing lipase activity, while retaining antioxidant activity, to stabilize whole wheat flour against lipid degradation during storage. Bran was heat-treated in 230-g batches using four levels (exposure times) for each of the three treatment methods. Lipase activity and antioxidant activity were quantified for all treatment combinations. None of the treatments significantly decreased antioxidant activity; the levels determined to be optimal, inasmuch as further heating did not significantly decrease lipase activity, were 25 min of dry heat, 60 sec of microwave (1000W), and 60 sec of steam. These treatments effectively decreased lipase activity by 74, 93, and 96%, respectively. Optimum treatments were evaluated for acceptance using a consumer sensory panel during a 12-month storage period. No significant differences in acceptance were found between the control and any of the samples either at baseline or after storage. This suggests that whole wheat flour can be stabilized against lipolysis by utilizing the treatments described in this study without decreasing antioxidant activity, and that manufacturers may utilize these treatments without risking decreased consumer acceptance.
The lipases responsible for the initiation of lipid degradation in milled wholemeal wheat products on storage were studied. Two major lipase activities were separated from whole flour samples by ion exchange chromatography on DE-32. The wheat lipases were found to be membrane-bound, but their activity could be solubilized with Triton X-100.
In order to study the lipases, a purification protocol was devised. Lipase activity was enriched by the isolation of membrane fragments, with the solubilized membrane proteins being fractionated by both DE-32 and hydroxylapatite chromatography. Purification was carried out using either whole flour, isolated bran or isolated germ as starting material. Properties of both the bran- and germ-derived lipases were studied. Different pH optima and heat stabilities were observed, indicating the involvement of two separate enzymes. The two lipases, however, were shown to have similar molecular weights of 67k (germ) and 70k (bran) and were, apparently, devoid of essential thiol groups.
The effect of a variety of metal ions and enzyme inhibitors on lipase preparations were evaluated, with a view to suggesting a means of controlling their activities. No potent inhibitors were shown under the conditions tested, although the addition of 100 mm NaCI was shown to cause a reduction in lipase activity of whole flour (55%).
The incipient rancidity of wholemeal flour, measured as the rate of oxygen uptake by aqueous suspensions, increased linearly with storage at 20 °C and was correlated closely (r = 0·96, P < 0·001) with increases in unesterified fatty acids. Fourteen out of 16 samples of finely-milled (< 0·5 mm) wholemeal from wheat of various origins showed similar rates of deterioration; one had a higher, and another a lower rate of deterioration. The rates of oxygen uptake by aqueous suspensions increased linearly with relative humidity (r.h.) during storage (from 5 to 81% r.h.) and were not due to microbial growth. Using finely-milled components of grain, the rate of deterioration of bran over 30 days at 20 °C was five-fold greater than that of a relatively pure germ fraction, but was only half the rate of a 5:1 (w/w) blend of bran and germ; increases in the rate of O2- uptake and fatty acid content were highly correlated (r = 0996, P < 0·001). Fine milling of bran, germ and blends increased the rate of deterioration and enhanced the observed synergistic effect between bran and germ on both 02 uptake and fatty acid increases. Lipid analyses of bran-germ blends supported the conclusion that, during storage, there is a relatively slow (over several weeks) release of fatty acids, catalysed by a lipolytic enzyme in the bran component of wholemeal, but that lipid oxidation occurs rapidly (within minutes) when excess water is added, facilitating lipoxygenase-catalysed peroxidation of polyunsaturated fatty acids.
Commercially produced wheat bran was stored at +20 or –20 °C, both as received and after further milling to give batches with different particle size distributions. The rates of deterioration of the bran and bran/flour blends were monitored by measurements of fatty acid contents and oxygen uptake of aqueous suspensions. During storage over 21 weeks the bran samples and bran/flour blends were subjected to sensory analysis. After storage for 4 weeks, untreated bran and finely milled (<0·5 mm) bran were blended with flour and baked into bread. The rates of deterioration were dependent upon particle size distribution in the bran. Finely milled bran, after storage at 20 °C for 4 weeks, gave a significantly lower loaf volume compared with untreated bran stored at +20 °C or with finely-milled bran stored at –20 °C. However, no significant differences in bread flavour were detected. The off-flavour intensity of bran-water mixtures increased as particle size decreased, and the differences in intensity between particle size fractions increased with the time of storage. Off flavour intensity scores, as reported by a taste panel, were highly correlated with oxygen uptake capacity (r2 = 0·998; P <0·001) and fatty acid content (r2 = 0·993; P <0·01) of the bran samples.
Three white bread flours, stored in good conditions for 5 years have been investigated for the presence of non-volatile oxidation products of linoleic acid. Two products have been identified and their rate of accumulation with time of storage determined.
The inactivation of rice bran lipase was studied in vitro and in vivo using metal ions in methanol or HCl. Lipase was extracted from rice bran in 0.1 M potassium phosphate buffer, pH 7.0 and purified by ammonium sulphate fractionation. The 25–55% ammonium sulphate fraction was subjected to DEAE-cellulose ion exchange chromatography and the fraction (F6) eluted at Ve/Vo of 14.37 was purified about 333-fold. In-vitro studies on F6 lipase showed that Fe3+ and Ni2+ completely inhibited the lipase activity at 5 × 10−5 M concentration, while Zn2+ and Cu2+ did so at 2.5 × 10−4 M. The results on in-vivo inactivation of rice bran lipase showed that Fe3+ and Ni2+ at 200 μg g−1 significantly checked the release of free fatty acids (FFA) from rice bran for 6 days of storage when compared with using concentrated HCl (2%, v/w) only. The triglyceride content of oil was also maximum with Fe3+ and Ni2+ treatment at 200 μg g−1. The present results suggest that Fe3+ and Ni2+ could be effectively used to arrest the release of FFA in rice bran and thus contribute to improving the edible quality of rice bran oil.
The purpose of this research was to develop a simple method for measuring lipase activity as an indicator of wheat and wheat
bran storage quality. This simplified method does not require the separation or purification of lipase. Optimal conditions
for lipase activity measurements were determined by varying the substrate (olive oil) and water concentrations, temperature,
and incubation time. Following incubation, FFA were quantified spectrophtometrically using a copper soap assay, and lipase
activity was expressed as units/gram (U/g), where 1 U was defined as the microequivalents of oleic acid liberated per hour.
The method was tested on one commercial and four pure wheat cultivars. The lipase activity was also correlated with the development
of FFA during actual storage of heat-treated commercial bran. Lipase activity in wheat bran ranged from 2.17 to 9.42 U/g,
and in whole kernel wheat from 1.05 to 3.54 U/g. Optimal olive oil and water concentrations were 0.4 to 0.8 mL and 0.15 to
0.20 mL per g of defatted sample, respectively. Optimal incubation temperature was 40°C, and incubation times of up to 8 h
were linear. Lipase activity was highly correlated with the buildup of FFA in stored wheat bran (R
2=0.97).
A new simple chemical method for stabilization of rice bran is described. The process, based on the principle that lipase
activity will be low at low pH, uses hydrochloric acid at 40 l/ton of bran for lowering the pH of rice bran from 6.9–6.0 to
4.0. The acid can be applied easily by sprinkling or spraying. The operation on small lots can be done by hand mixing of bran,
but it is more efficient and effective if mechanical mixing, like a rotary or a trough mixer, is used. This simple method,
which takes less than 4 min for a batch of 15 kg, will be useful for stabilization of rice bran in rice mills or where steam
or electricity is unavailable. The process is being evaluated in commercial trials.
The vast majority of bread is traditionally produced from wheat flour. Apart from its major constituent starch, wheat flour also contains many other types of substances of which the gluten, the non-starch polysaccharides as well as the lipids are the most important in terms of their impact on the processability of the raw material and in terms of the quality of the final products. We here provide the basics on the processability and quality determining wheat flour constituents and present common concepts on their fate during the breadmaking process as well as on approaches targeted to influence their functionality.
The oxygen consumption values (µmol O2/10 min/g at 25°C) of aqueous suspensions of wheat wholemeal (0·1–3·0, bran (1–18) and germ (1–11) are substantially higher than those of white flours (0·01–0·03). The actual values depend upon storage history; the O2 consumption value of materials stored 2–4 weeks at 20°C, 65% r.h. are many-fold higher than those of the same materials from freshly-milled grain. The O2 consumption of mixtures of finely-ground (< 0·5 mm) bran and germ increases on storage more rapidly than that of bran or germ stored separately. The O2 uptake is due primarily to oxidation of unesterified, polyunsaturated fatty acids, catalysed by lipoxygenase that is concentrated in the germ fraction. The increased O2 demand of stored materials is due to higher levels of polyunsaturated fatty acids, released during storage, by hydrolysis of triacylglycerols, catalysed by a triacylglycerol hydrolase (lipase) that is concentrated in the bran fraction. The triacylglycerol-hydrolase activity of wheat germ is relatively low. Thus, O2-uptake by aqueous suspensions of wholemeal flour can be explained in terms of the combined effects of the bran component, causing lipolysis during storage of wholemeal, and the germ component, catalysing the O2-dependent peroxidation of polyunsaturated fatty acids when the wholemeal is added to water; both bran and germ components contribute triacylglycerols as the substrates for lipolysis.
Ozonated water is reported to be effective in reducing the microbial load in foods such as fruits, vegetables, and grains. Ozonated water may be an effective alternative to chlorinated water in treating durum wheat before milling. Therefore, durum wheat was washed with ozonated water and analyzed for yeast and mold count (YMC) and aerobic plate count (APC). A system for producing and monitoring ozonated water was developed. The effect of water quality (tap, distilled, and ultra-pure), temperature (7, 15, and 25 degrees C), and pH (2, 4, and 6.5) was evaluated on the following: steady-state dissolved ozone concentration, ozone decay constant, half-life, mass transfer coefficient, equilibrium ozone concentration, and solubility ratio. The study of these parameters was important to attain a stable, high dissolved ozone concentration at the outset of washing and to have information for system improvement and scale-up. A 1% acetic acid solution (pH 2) at 15 degrees C resulted in high dissolved ozone concentration (21.8 mg/L) and long half-life (9.2 min). Subsequently, wheat was washed with 5 wash water types: distilled water, ozonated water (16.5 mg/L), chlorinated water (700 mg/L), acetic acid solution (1%), and acetic acid + ozonated water (1%, 20.5 mg/L). The treated samples were analyzed for YMC and APC. The acetic acid + ozonated water treatment was the most effective, with a reduction of 4.1 and 3.2 log(10) colony forming units/g in YMC and APC, respectively. Though ozonated water was not very effective alone, it was useful in combination with acetic acid.
Both the natural lipids of flour and added fats are known to play an important role during the production of bread. In this review, the chemical and physical interactions of fat have been assessed in an attempt to explain these technological functions. Particular emphasis has been placed on the "binding" or complexing of lipid by flour proteins during the development of dough. While publications in this field have frequently been contradictory, evidence now indicates that observed lipid binding may involve lipid mesophase transformation and the nonspecific occlusion of lipid phases within the gluten network. The significance of these suggested events has been compared with current theories of lipid function in the breadmaking process.
We identified volatile compounds of barley flour and determined the variation in volatile compound profiles among different types and varieties of barley. Volatile compounds of 12 barley and two wheat cultivars were analyzed using solid phase microextraction (SPME) and gas chromatography. Twenty-six volatiles comprising aldehydes, ketones, alcohols, and a furan were identified in barley. 1-Octen-3-ol, 3-methylbutanal, 2-methylbutanal, hexanal, 2-hexenal, 2-heptenal, 2-nonenal, and decanal were identified as key odorants in barley as their concentration exceeded their odor detection threshold in water. Hexanal (46-1269 microg/L) and 1-pentanol (798-1811 microg/L) were the major volatile compounds in barley cultivars. In wheat, 1-pentanol (723-748 microg/L) was a major volatile. Hulled barley had higher total volatile, aldehyde, ketone, alcohol, and furan contents than hulless barley, highlighting the importance of the husk in barley grain aroma. The proanthocyanidin-free varieties generally showed higher total volatile and aldehyde contents than wild-type varieties, potentially due to decreased antioxidant activity by the absence of proanthocyanidins.
A high sodium intake, to which bread makes a major contribution, and a low potassium intake are believed to be important factors in the promotion of cardiovascular disease. Our aims was to determine to what extent salts of potassium could substitute sodium chloride and potassium-rich soya flour could replace wheat flour without detrimental effect on acceptability, and to measure the bioavailability of a potassium salt added to bread. A single-blind organoleptic evaluation was carried out on eight different potassium-enriched breads by 41 panellists. Thereafter, six volunteers consumed standard or potassium-chloride-fortified bread in an 11-day single-blind cross-over feeding trial to determine the bioavailability of the supplemental potassium. Two breads in which 30% of the sodium was replaced by potassium salts, and bread in which 10% of wheat flour was replaced with soy flour, had acceptability scores similar to the standard bread. In the metabolic study a supplement of 22 mmol/day potassium chloride incorporated into the bread was found to be wholly bioavailable. A substantial reduction in sodium and an increase in potassium intake could be achieved by substituting potassium salts for sodium chloride in bread.
Looking for my lost shaker of salt. . .replacer: Flavor, function, future. Cereal Foods World
- B B Heidolph
- D K Ray
- S Roller
- P Koehler
- J Weber
- S Slocum
- M W J Noort
Heidolph, B. B., Ray, D. K., Roller, S., Koehler, P., Weber, J., Slocum, S., & Noort, M. W. J. (2011). Looking for my lost shaker of salt...replacer: Flavor, function, future. Cereal Foods World, 65, 5–19.
Recommendations on wheat and maize flour fortification, meeting report: Interim consensus statement Available at: http://www.who.int/ nutrition
- Pdf A F Doblado-Maldonado
WHO (2009). Recommendations on wheat and maize flour fortification, meeting report: Interim consensus statement. Available at: http://www.who.int/ nutrition/publications/micronutrients/wheat_maize_fort.pdf. A.F. Doblado-Maldonado et al. / Food Chemistry 140 (2013) 204–209