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1.
Gliadins are among the most important protein fractions affecting wheat baking quality, but they are also plant allergens and a cause of celiac disease or food intolerance. Therefore, we investigated how gliadin immunoreactivity and dough rheological properties are influenced by thioredoxin, a regulatory disulfide protein that can reduce disulfide bonds, a typical motive in many allergenic proteins. Ten winter wheat genotypes of different qualities were analyzed. Reduction by thioredoxin strongly (>50%) decreased gliadin immunoreactivity as estimated by enzyme‐linked immunosorbent assay with immunoglobulin E (IgE) sera from allergic patients and standard antigliadin antibodies but did not significantly affect dough rheological properties. Most parameters from the Brabender extensigraph were only slightly lower. Simultaneously, the farinograph curve exhibited a drawdown dislocation, possibly due to increased water absorption by modified flour, and dough consistency visibly improved. Results suggest that thioredoxin may be a universal natural beneficial modifier, able to significantly decrease gliadin immunoreactivity (hence its potential allergenicity) without decreasing the unique technological properties of wheat flour. 相似文献
2.
S. Uthayakumaran H. L. Beasley F. L. Stoddard M. Keentok N. Phan‐Thien R. I. Tanner F. Bks 《Cereal Chemistry》2002,79(2):294-300
The high molecular weight glutenin subunits (HMW‐GS) play an important role in governing the functional properties of wheat dough. To understand the role of HMW‐GS in defining the basic and applied rheological parameters and end‐use quality of wheat dough, it is essential to conduct a systematic study where the effect of different HMW‐GS are determined. This study focuses on the effect of HMW‐GS on basic rheological properties. Eight wheat lines derived from cvs. Olympic and Gabo were used in this study. One line contained HMW‐GS coded by all three loci, three lines were each null at one of the loci, three lines were null at two of the loci and one line null at all three loci. The flour protein level of all samples was adjusted to a constant 9% by adding starch. In another set of experiments, in addition to the flour protein content being held at 9%, the glutenin‐to‐gliadin ratio was maintained at 0.62 by adding gliadin. Rheological properties such as elongational, dynamic, and shear viscometric properties were determined. The presence of Glu‐D1 subunits (5+10) made a significantly larger contribution to dough properties than those encoded by Glu‐B1 (17+18), while subunit 1, encoded by Glu‐A1, made the least contribution to functionality. Results also confirmed that HMW‐GS contributed to strength and stability of dough. 相似文献
3.
R. I. Snchez-Mariez M. O. Cortez-Rocha F. Ortega-Dorame M. Morales-Valdes M. I. Silveira 《Cereal Chemistry》1997,74(4):481-483
The objective of this study was to evaluate how Rhyzopertha dominica infestation of stored wheat grain affects the rheological and baking properties of bread made with the milled flour. Wheat samples were infested with R. dominica and stored for up to 180 days at room temperature. Every 45 days, samples of wheat were collected and evaluated for insect population and flour yield. Flour milled from these wheat samples was evaluated for color reflectance, pH, fat acidity, and rheological properties which were measured by a farinograph. Loaves of bread were baked using a straight-dough procedure. Volume, height, and weight of the loaves were evaluated. None of the analyses performed on the control wheat flours showed any changes during the storage period, and they were similar to the initial wheat. The insect population increased during storage of the wheat up to 90 days, and the flour yield decreased with the storage up to 180 days. Flours from insect-infested wheat absorbed more water than did flours from control wheat. Dough stability and dough development times of infested flours decreased. Bread volume showed a progressive decline throughout the storage experiment. In conclusion, flour from insect-infested wheat exhibited changes in rheological properties such as dough stability, dough development times, water absorption, and mixing stability; bread had an offensive odor; and volume and loaf characteristics were negatively affected. 相似文献
4.
The baking properties of several genotypes of U.S. hard wheats grown in state nurseries for the Wheat Quality Council (WQC) were analyzed by the Hard Winter Wheat Quality Laboratory. Flours (250 mg) from each individual line and location were extracted three times with 50% 1- propanol (1 mL) for 5 min each. Samples were vortexed continually during extraction. This method was effective in removing most monomeric proteins. Negligible detectable protein was found in the third extract. Significant amounts of polymeric glutenin were also extracted. Pellets were oven-dried (130°C) for 1 hr and analyzed for protein content using nitrogen combustion analysis. Protein remaining in the pellet consisted mainly of polymeric protein. The amount of gliadin and soluble polymeric protein could also be measured by separating the supernatant by size-exclusion chromatography. Good correlations between dough strength parameters and amounts of pellet protein and the relative amount of pellet protein (pellet protein/flour protein) were found for all samples. This procedure was simple and rapid, with the potential of analyzing large numbers of samples per day with good reproducibility. 相似文献
5.
Relaxation behavior was measured for dough, gluten and gluten protein fractions obtained from the U.K. biscuitmaking flour, Riband, and the U.K. breadmaking flour, Hereward. The relaxation spectrum, in which relaxation times (τ) are related to polymer molecular size, for dough showed a broad molecular size distribution, with two relaxation processes: a major peak at short times and a second peak at times longer than 10 sec, which is thought to correspond to network structure, and which may be attributed to entanglements and physical cross‐links of polymers. Relaxation spectra of glutens were similar to those for the corresponding doughs from both flours. Hereward gluten clearly showed a much more pronounced second peak in relaxation spectrum and higher relaxation modulus than Riband gluten at the same water content. In the gluten protein fractions, gliadin and acetic acid soluble glutenin only showed the first relaxation process, but gel protein clearly showed both the first and second relaxation processes. The results show that the relaxation properties of dough depend on its gluten protein and that gel protein is responsible for the network structure for dough and gluten. 相似文献
6.
S. Uthayakumaran M. Newberry M. Keentok F. L. Stoddard F. Bekes 《Cereal Chemistry》2000,77(6):744-749
The uniaxial elongational and shear rheology of doughs varying in either the protein content or glutenin‐to‐gliadin ratio were investigated. Increasing the protein content at constant glutenin‐to‐gliadin ratio increased the strain‐hardening properties of the dough, as shown by increasing elongational rupture viscosity and rupture stress. Glutenin and gliadin had a more complex effect on the elongational properties of the dough. Increased levels of glutenin increased the rupture viscosity but lowered the rupture strain, while elevated gliadin levels lowered the rupture viscosity but increased the rupture strain. These observations provide rheological support for the widely inferred role of gliadin and glutenin in shaping bread dough rheology, namely that gliadin contributes the flow properties, and glutenin contributes the elastic or strength properties. The shear and elongational properties of the doughs were quite different, reflecting the dissimilar natures of these two types of flow. Increasing protein content lowered the maximum shear viscosity, while increasing the glutenin‐to‐gliadin ratio increased maximum shear viscosity. Strong correlations between the results of basic and empirical rheology were found. These basic, or fundamental, rheological measurements confirmed prior empirical studies and supported baking industry experience, highlighting the potential of basic rheology for bread and wheat research. 相似文献
7.
The effect of genetic substitution of two to four glutenin and gliadin subunits from a Canada Prairie Spring (CPS) cv. Biggar BSR into Alpha 16, another CPS wheat line, was studied for rheological and baking quality. Results from double substitution showed that the presence of a gliadin component from Biggar BSR (BGGL) and low molecular weight glutenin subunit 45 (LMW 45) contributed to improved dough strength characteristics. Presence of BGGL in combination with high molecular weight glutenin subunit 1 (HMW 1) or 17+18 (HMW 17+18) also showed improved dough strength over control Alpha lines. When three or four protein subunits were substituted, even though improved quality performance was observed, it was associated with the negative effect of lowered flour water absorptions in spite of similar protein contents. The study confirms that LMW glutenins, as well as gliadins, play an important role along with HMW glutenins in wheat flour quality. CPS wheat lines with improved dough strength properties can be selected from the double substitution lines with the combination of BGGL/LMW 45 and BGGL/HMW 1. 相似文献
8.
Six genotypes of hard red spring (HRS) wheat were grown at seven environments in North Dakota during 1998. Effects of genotype and environment on glutenin polymeric proteins and dough mixing and baking properties were examined. Genotype, environment, and genotype‐by‐environment interaction all significantly affected protein and dough mixing properties. However, different protein and quality measurements showed differences for relative influences of genotype and environment. Total flour protein content and SDS‐soluble glutenin content were influenced more by environmental than genetic factors, while SDS‐insoluble glutenin content was controlled more by genetic than environmental factors. Significant genotypic and environmental effects were found for the size distribution of SDS‐soluble glutenins and between SDS‐soluble and SDS‐insoluble glutenins as well as % SDS‐insoluble glutenins. With increased flour protein content, the proportions of monomeric proteins and SDS‐insoluble glutenin polymers appeared to increase, but SDS‐soluble glutenins decreased. Flour protein content and the size distribution between SDS‐soluble and SDS‐insoluble glutenin polymers were significantly correlated with dough mixing properties. Environment affected not only total flour protein content but also the content of different protein fractions and size distributions of glutenin polymers, which, in turn, influenced properties of dough mixing. Flour protein content, % SDS‐insoluble glutenin polymers in flour, and ratio of SDS‐soluble to SDS‐insoluble glutenins all were highly associated with dough mixing properties and loaf volume. 相似文献
9.
Kari M. Tronsmo Ellen Merethe Magnus Ellen Mosleth Frgestad J. David Schofield 《Cereal Chemistry》2003,80(5):575-586
The rheological properties of fresh gluten in small amplitude oscillation in shear (SAOS) and creep recovery after short application of stress was related to the hearth breadbaking performance of wheat flours using the multivariate statistics partial least squares (PLS) regression. The picture was completed by dough mixing and extensional properties, flour protein size distribution determined by SE‐HPLC, and high molecular weight glutenin subunit (HMW‐GS) composition. The sample set comprised 20 wheat cultivars grown at two different levels of nitrogen fertilizer in one location. Flours yielding stiffer and more elastic glutens, with higher elastic and viscous moduli (G′ and G″) and lower tan δ values in SAOS, gave doughs that were better able to retain their shape during proving and baking, resulting in breads of high form ratios. Creep recovery measurements after short application of stress showed that glutens from flours of good breadmaking quality had high relative elastic recovery. The nitrogen fertilizer level affected the protein size distribution by an increase in monomeric proteins (gliadins), which gave glutens of higher tan δ and flatter bread loaves (lower form ratio). 相似文献
10.
Fluids applied to large‐sale, technical separation of wheat starch and protein also extract soluble proteins. The degree and rate of extraction and the specific components extracted depend on the flour, the flour hydration and development, the starch‐displacing fluid composition, the temperature, and the mechanical processing method. This study sought to identify major extracted protein groups using high‐performance capillary zone electrophoresis (CZE) applied directly to fluids obtained during laboratory‐scale technical separations. A dough‐ball or compression separation method was applied using a Glutomatic system and a batter or dispersion method was applied using a a McDuffie mixer and Pharmasep vibratory separator. Process fluids were water at 22°C to model commercial practice and 70 vol% ethanol in water at ‐13°C to model the cold ethanol process being developed here. Data were referenced to use of 70 vol% ethanol in water at 22°C in the Glutomatic compression method. The dough processed by each method was developed by mixing to a separable state. When flooded with excess water, this dough immediately released starch and water‐soluble or albumin proteins. When flooded with excess cold aqueous ethanol, neither the albumin nor gliadin proteins appeared in significant amounts until the bulk of the starch had been displaced, regardless of the mechanical method. Even with extraction and manipulation well beyond that necessary for starch displacement, the net amount of gliadin proteins dissolved was only ≈10% of that available from wet developed dough using 70 vol% ethanol at 22°C. There was more gliadin protein in the fluids at earlier stages of processing when the batter dispersion method was applied using cold ethanol. The most common soluble proteins revealed in the electrophoresis patterns for the batter compression method using cold aqueous ethanol were initially albumins and later γ‐gliadins. Albumins not appearing as soluble in cold 70 vol% ethanol were found in the insoluble crude starch, suggesting their precipitation in the dough fluids during the change from free water to cold aqueous ethanol. These results establish that some protein is dissolved during starch displacement by cold aqueous ethanol, but that the amounts may be limited by control of the mechanical working of the dough in the presence of the displacing fluids. 相似文献
11.
Mariotti M Lucisano M Pagani MA Iametti S 《Journal of agricultural and food chemistry》2008,56(11):4258-4267
The physicochemical properties of the protein and starch fractions of flour obtained from buckwheat grains that were previously dehulled or puffed after dehulling were investigated. Dehulling removed most of the nonprotein, nonstarch components of the grain, without affecting the chemical and structural features of the protein and starch components, as made evident by microstructural and spectroscopic measurements. Puffing resulted in extensive modifications of the interprotein network as well as in most of the properties of the buckwheat starch. Flours obtained from dehulled or puffed after dehulling grains were blended with 60-80% wheat flour and tested for their dough-making ability. Blends containing dehulled and puffed buckwheat flours gave dough of much lower quality than dehulled, but had water-holding properties that may be of interest for the shelf life of baked products. 相似文献
12.
Noor Hasniza M. Z. Meredith A. Wilkes Surjani Uthayakumaran Les Copeland 《Cereal Chemistry》2014,91(2):169-175
The objectives of this study were to assess how functional properties of proteins in whole meal wheat (Triticum aestivum L.) flour vary across different growth environments. Grain from three commercial Australian Hard milling wheat cultivars was analyzed from four growth locations in 2008 and from two of the corresponding cultivars and locations in 2009. The protein content of the grain, soluble and insoluble extractable protein fractions, swelling index of glutenin (SIG), glutenin‐to‐gliadin ratio (Glu:Gli), percent unextractable polymeric protein (%UPP), and dough properties including force at maximum resistance (Rmax) and extensibility were measured. Based on analysis of variance of aggregated data for the cultivars, growth locations, and seasons, growth environment factors made significant contributions to variability in the total grain protein, Glu:Gli ratio, %UPP, SIG, Rmax, and extensibility of the wheat flour. Variability of protein content of the soluble and insoluble extractable protein fractions was mostly owing to genotype. 相似文献
13.
We investigated the relationship between the protein content and quality of wheat flours and characteristics of noodle dough and instant noodles using 14 hard and soft wheat flours with various protein contents and three commercial flours for making noodles. Protein content of wheat flours exhibited negative relationships with the optimum water absorption of noodle dough and lightness (L*) of the instant noodle dough sheet. Protein quality, as determined by SDS sedimentation volume and proportion of alcohol‐ and salt‐soluble protein of flour, also influenced optimum water absorption and yellow‐blueness (b*) of the noodle dough sheet. Wheat flours with high protein content (>13.6%) produced instant noodles with lower fat absorption, higher L*, lower b*, and firmer and more elastic texture than wheat flours with low protein content (<12.2%). L* and free lipid content of instant noodles were >76.8 and <20.8% in hard wheat flours of high SDS sedimentation volume (>36 mL) and low proportion of salt‐soluble protein (<12.5%), and <75.7 and >21.5% in soft wheat flours with low SDS sedimentation volume (<35 mL) and a high proportion of salt‐soluble protein (>15.0%). L* of instant noodles positively correlated with SDS sedimentation volume and negatively correlated with proportion of alcohol‐ and salt‐soluble protein of flour. These protein quality parameters also exhibited a significant relationship with b* of instant noodles. SDS sedimentation volume and proportion of salt‐soluble protein of flours also exhibited a significant relationship with free lipid content of instant noodles (P < 0.01 and P < 0.001, respectively). Protein quality parameters of wheat flour, as well as protein content, showed significant relationship with texture properties of cooked instant noodles. 相似文献
14.
Flours obtained by a specific polishing process were used to prepare sourdough and bread. Three fractions designated C‐1 (100–90%), C‐5 (60–50%), and C‐8 (30–0%) were studied. The pH, total titratable acidity levels, and buffering capacity of sourdoughs made from polished flours were significantly different from those of the control sourdough with No. 1 Canada Western Red Spring (CW), and they provided sourdough breads with better qualities than that of CW. The growth of lactic acid bacteria and yeast in polished flour sourdoughs were significantly accelerated during fermentation over that in CW sourdough. Higher maturation of polished flour sourdoughs softened the hardness of mixed dough. The intricate network of honeycomb structure gluten and uneven surface of starch granules were distinctly observed in SEM images. Substitutions of C‐5 or C‐8 sourdoughs for CW significantly increased the loaf volume and softened breadcrumbs more than CW sourdough. Flour qualities of polished flours such as suitable acidity and good buffering capacity caused by the bran fraction were effective for better growth and longer life of yeast in the dough during fermentation. Therefore, application of polished flours in sourdough bread would improve rheological properties of dough and bread as compared with CW sourdough. 相似文献
15.
Relationships between flour functional properties and protein composition were studied using a set of 138 Argentinean wheat samples. Among different protein groups, the incremental increase of gliadin with increasing grain protein content was highest followed by polymeric protein with albumin‐globulin content much lower. Functional properties could be divided into two groups based on dependence on protein composition. Properties such as dough extensibility and bake test loaf volume correlated highly with the percentage of polymeric protein in the grain. Properties such as mixograph dough development time were best correlated with the percentage of polymeric protein in the protein (PPP). Alveograph tenacity showed no significant dependence on PPP. as found previously for extensigraph maximum resistance, but it was correlated with the percentage of unextractable polymeric protein in the protein. Energy (W) appeared to be a more useful alveograph parameter for predicting flour quality. 相似文献
16.
《Cereal Chemistry》2017,94(5):881-886
In this study, the impact of characteristics (physicochemical, rheological, and pasting properties) of different wheat flours on the quality of frozen cooked noodles was investigated. In this sample set, results showed the cooking loss of noodles related negatively to flour swelling power. The water absorption of noodles related negatively to the dough stability time, the area, and the resistance to extension. The wheat flour with higher dough development time resulted in frozen cooked noodles with higher hardness, chewiness, and adhesiveness. Springiness of noodles correlated negatively to degree of softening. The tensile properties of frozen cooked noodles were influenced by rheological and pasting properties of wheat flours. The present study indicated high quality of frozen cooked noodles demanded wheat flours with high dough gluten strength, peak viscosity, and final viscosity and with low pasting temperature. 相似文献
17.
The aim of this study was to analyze sulfur content, protein size distribution, and free amino acids in flour mill streams (FMS) and their associations to dough rheology and breadmaking traits. Break FMS had higher nitrogen and sulfur quantities than reduction FMS. The third break FMS had the highest nitrogen and sulfur contents among FMS but low bread loaf volume partly due to high ash content. Sulfur quantity had greater or equivalent correlations with dough rheology and breadmaking properties compared with nitrogen quantity when the effect of percent ash content was removed statistically. FMS also showed significant quantitative variation in HMW polymeric proteins of the SDS‐unextractable fraction that had greater association with sulfur content and dough rheology and breadmaking traits than other protein fractions. Asparagine, which is a major amino acid in flour, was found at higher levels in the third break and third reduction FMS. Ratio of nitrogen to sulfur was significantly correlated with asparagine concentration (r = 0.73, α = 0.01). This study indicates that information on sulfur, protein size distribution, and free amino acid is potentially useful in research for more precise blending of FMS in commercial flour mills to meet customer specifications for high quality flour. 相似文献
18.
The effect of flour type and dough rheology on cookie development during baking was investigated using seven different soft winter wheat cultivars. Electrophoresis was used to determine the hydrolyzing effects of a commercial protease enzyme on gluten protein and to evaluate the relationships between protein composition and baking characteristics. The SDS‐PAGE technique differentiated flour cultivars based on the glutenin subunits pattern. Electrophoresis result showed that the protease degraded the glutenin subunits of flour gluten. Extensional viscosities of cookie dough at all three crosshead speeds were able to discriminate flour cultivar and correlated strongly and negatively to baking performance (P < 0.0001). The cookie doughs exhibited extensional strain hardening behavior and those values significantly correlated to baking characteristics. Of all rheological measurements calculated, dough consistency index exhibited the strongest correlation coefficient with baking parameters. The degradation effects of the protease enzyme resulted in more pronounced improvements on baking characteristics compared with dough rheological properties. Stepwise multiple regression showed that the dough consistency index, the presence or absence of the fourth (44 kDa) subunit in LMW‐GS and the fifth subunit (71 kDa) subunit in HMW‐GS were predominant parameters in predicting cookie baking properties. 相似文献
19.
The application of the cold‐ethanol laboratory fractionation method to the bulk separation of wheat starch and gluten is accompanied by incidental dissolution, removal, or redeposition of a small part of the functional gliadin protein. The new distribution resulting from process incidental redeposition of soluble components or by purposeful add‐back of soluble and leached components can lead to differences in functionality and more difficult recovery of native properties. To assess this issue, we exposed several wheat flour types to ethanol and water (50–90% v/v) solutions, water, and absolute ethanol at 22°C and –12°C. The exposure was mass conserving (leached components returned to substrate by evaporation of the solvent without separation of phases) or mass depleting (leached components not returned to substrate). The result of the mass‐conserving contact would be flour with altered protein distributions and intermolecular interactions. The result of the mass‐depleting contact would also include altered protein content. Furthermore, the mass‐conserving contact would model an industrial outcome for a cold‐ethanol process in which leached components would be added back from an alcohol solution. The leaching result was monitored by mixography of the flour, nitrogen analysis, and capillary zone electrophoresis of extracts. Although dough rheology was generally like that of the source flour, there were notable differences. The primary change for mass‐conserving contact was an increase in the time to peak resistance and a decrease in the rate of loss of dough resistance following peak resistance. These changes were in direct proportion to the amount of protein mobilized by the solvent. Leaching at 22°C, prevented dough formation for most aqueous ethanol concentrations and greatly reduced gliadin protein content. Minimal changes were noted for solvent contact at –12°C regardless of the ethanol concentration. The data suggested that 1) the conditions applied in cold‐ethanol enrichment of protein from wheat will generally preserve vital wheat gluten functionality, 2) functionality losses can be recovered by returning the solubilized fractions, and 3) the flour to which the gluten is added may require more mixing. 相似文献
20.
H. L. Beasley S. Uthayakumaran F. L. Stoddard S. J. Partridge L. Daqiq P. Chong F. Bks 《Cereal Chemistry》2002,79(2):301-307
Understanding the relationship between basic and applied rheological parameters and the contribution of wheat flour protein content and composition in defining these parameters requires information on the roles of individual flour protein components. The high molecular weight glutenin subunit (HMW‐GS) proteins are major contributors to dough strength and stability. This study focused on eight homozygous wheat lines derived from the bread wheat cvs. Olympic and Gabo with systematic deletions at each of three HMW‐GS encoding gene loci, Glu‐A1, Glu‐B1, and Glu‐D1. Flour protein levels were adjusted to a constant 9% by adding starch. Functionality of the flours was characterized by small‐scale methods (2‐g mixograph, microextension tester). End‐use quality was evaluated by 2‐g microbaking and 10‐g noodle‐making procedures. In this sample set, the Glu‐D1 HMW‐GS (5+10) made a significantly larger contribution to dough properties than HMW‐GS coded by Glu‐B1 (17+18), while subunit 1 coded by Glu‐A1 made the smallest contribution to functionality. These differences remained after removing variations in glutenin‐to‐gliadin ratio. Correlations showed that both basic rheological characteristics and protein size distributions of these flours were good predictors of several applied rheological and end‐use quality tests. 相似文献