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1.
The contribution of the diploid wheat species Aegilops tauschii (Coss.) Schmall to the technological properties of bread wheat (Triticum aestivum L.) was previously studied by the investigation of synthetic hexaploids derived from tetraploid durum wheat (T. turgidum L.) and three diploid Ae. tauschii lines. The results indicated that bread volume, gluten index, SDS‐sedimentation volume, and maximum resistance of gluten were significantly influenced by the Ae. tauschii lines. To determine the relationship between technological properties and qualitative and quantitative compositions of gluten proteins, the flours of parental and synthetic lines were extracted using a modified Osborne fractionation. Gliadin and glutenin fractions were then characterized by reversed‐phase (RP) HPLC on C8 silica gel. The HPLC patterns revealed typical differences between synthetic and parental lines. The gliadin patterns of three synthetic lines and the glutenin patterns of two synthetic lines were more similar to that of the diploid Ae. tauschii parents involved in the hybrids. In the glutenin pattern of one synthetic line, characteristics from both Ae. tauschii and the durum wheat parents were observed. The amount of total gliadin and gliadin types of the synthetic lines was mostly intermediate between those of the durum and Ae. tauschii parents. The amounts of total glutenin and glutenin types (HMW and LMW subunits) of the synthetic lines were generally higher than those of the parental lines, and the ratio of gliadins to glutenins was significantly decreased. High positive correlations were found between the amount of total glutenins, HMW, and LMW subunits and bread volume, maximum resistance and extension area of gluten, and SDS‐sedimentation volume. The ratio of gliadins to glutenin subunits had a strong negative influence on these properties. The protein content of the flours and the amount of total gluten proteins were not correlated with any of the technological properties. Results on the relationship between biochemical characteristics and the breadmaking properties indicated that wheat prebreeding would benefit from studies on protein types and quantification in the choice of parents. In addition, the potential of the diploid Ae. tauschii for improvement of breadmaking quality should be further exploited. 相似文献
2.
The baking performance of a set of flours from 13 wheat cultivars was determined by means of two different microscale baking tests (10 g of flour each). In the micro‐rapid‐mix test the dough was mixed for a fixed time at a high speed, whereas the microbaking test used mixing to optimum dough consistency in a microfarinograph. Quality parameters such as sedimentation value, crude protein content, dough and gluten extension data, and microfarinograph data were also determined. Finally, quality‐related protein fractions (gliadins, glutenins, SDS‐soluble proteins, and glutenin macropolymer) were quantitated by extraction/HPLC methods with reversed‐phase and gel‐permeation columns. All quality parameters were correlated with the bread volumes of both baking tests. The results demonstrated that the microbaking test (adapted mixing time) was much more closely related to the quality parameters than the micro‐rapid‐mix test (fixed mixing time), which hardly showed any correlation. Among the standard quality parameters, only the crude protein content showed a medium correlation with the bread volume of the microbaking test (r = 0.71), whereas the contents of gliadins (r = 0.80), glutenins (r = 0.76), and glutenin macropolymer (r = 0.80) appeared to be suitable parameters to predict the baking performance of wheat flour. All other quality parameters were not or were only weakly correlated and unsuitable for predicting baking performance. 相似文献
3.
Dragan R.
ivan
ev Aleksandra M. Torbica Jelena M. Tomi&#x; Elizabet P. Jani&#x; Hajnal Miona M. Belovi&#x; Jasna S. Mastilovi&#x;
arko S. Kevre&#x;an 《Cereal Chemistry》2016,93(1):90-99
The primary goal of this study is to improve our understanding of the extent of influence of climatic factors in Serbia and high‐molecular‐weight glutenin subunit (HMW‐GS) composition upon wheat end‐use quality. In‐depth analyses were performed on four bread wheat cultivars that are the most common in agricultural practice in Serbia. Total glutenin content showed significant difference between the production years, in opposition to gliadins. Cluster analysis of different percentages of glutenin and gliadin subunit molecular weight ranges (<40,000, 40,000–80,000, 81,000–120,000, and >120,000) indicated that the year of production and the cultivar did not have a significant effect on the percentage ranges for glutenins. However, they had a considerable impact on the percentage ranges for gliadins. Production year and the interaction of year and cultivar had the strongest influences on the percentage of SDS‐unextractable polymeric proteins. A synergistic effect of the HMW‐GS composition and climatic conditions revealed that all eight samples with HMW‐GS composition 2*, 5 + 10, 7 + 9 along with the highest Glu 1 score of 9 (out of a maximum of 10) produced in the year 2011 belonged to two clusters with the best wheat end‐use quality. Furthermore, the climate conditions in 2011 made it possible for the wheat cultivars with HMW‐GS composition –, 2 + 12, 7 + 9 to possess similar qualities as cultivars with HMW‐GS composition 2*, 5 + 10, 7 + 9 produced in 2012. 相似文献
4.
Three winter wheat varieties with differing breadmaking quality were grown at two locations in two years at 0 or 3 × 60 kg of nitrogen application. The effect of nitrogen on amount of different components of gluten proteins was determined by reverse-phase HPLC. A high amount of nitrogen led generally to a significant increase of total protein content. However, this increase was obvious only for the gluten proteins; albumins and globulins remained nearly unaffected. The effect of increased protein content on gliadin to glutenin (gli-glu) ratio was inconsistent. While increased protein content increased the gli-glu ratio in the variety Capo, the opposite was true for the variety Renan. Gli-glu ratio of the variety Lindos showed no discernible tendency. As total protein content increased, the ratio of low molecular weight (LMW) to high molecular weight (HMW) glutenins decreased consistently, i.e., in all varieties, in both years and locations. Change of LMW to HMW ratio showed a significant negative correlation to sedimentation value and bread volume. There was no consistent change in the ratio between x- and y-type HMW subunits due to fertilization, as could be shown by densitometric measurements on SDS-PAGE gels. This ratio appeared to be dependent on the genotype and has decreased with decreasing quality. The amount of x-type subunits correlated closely with sedimentation value and bread volume. These results suggest that ratio of HMW glutenins, especially x-type subunits, to total protein content could be the best early detectable parameter with high predictive value for breadmaking quality. 相似文献
5.
Concepcin L. Medina‐Rodríguez Patricia Torres Fernando Martínez‐Bustos Benjamin Ramirez‐Wong Octavio Paredes‐Lpez Eduardo Castao‐Tostado 《Cereal Chemistry》2009,86(2):127-132
Microbial transglutaminase (MTGase), a protein‐glutamine γ‐glutamyl transferase (E.C. 2.3.2.13), catalyzes acyl transfer reactions by introducing a covalent cross‐link between l ‐lysine and l ‐glutamine residues. The use of this enzyme has been proposed as an improver to increase dough strength. The objective of this study was to assess and compare the effect of MTGase on different fractions of dough proteins found in hard, soft, and durum wheat. Three different concentrations of the MTGase (0, 5, and 10U/g of gluten) were tested. Moisture, protein, and dry gluten contents were determined for each concentration in addition to rheological measurements done with the farinograph. Following each treatment, the dough proteins were extracted and analyzed by SE‐HPLC and RP‐HPLC. Soluble polymeric protein, gliadins, albumins, and globulins were quantified in addition to the gliadin subclasses and glutenin subunit types. The combustion procedure was used to determine the amount of insoluble polymeric protein. Differences were observed in susceptibility to MTGase catalysis among the dough proteins of the cultivars studied: the cultivar Cortazar (soft wheat) was the most susceptible. The proteins of this cultivar had a characteristically higher amount of ω and α+β gliadins when compared with the other cultivars. As reported earlier, solubility of high molecular weight glutenin subunits and ω‐gliadins was reduced because of the MTGase treatment. However, all gliadin subclasses, including the γ and α+β gliadins, also participated in cross‐linking. The proteins of the cultivar Altar (durum wheat) were the least susceptible to the effects of MTGase. Albumins and globulins did not show any reduction in solubility, implying that they did not participate in cross‐linking. 相似文献
6.
The objective of this study was to investigate the quantitative variation of HMW glutenin subunits in relation to glutenin polymers and hence breadmaking quality across different environments. Six genotypes of hard red spring (HRS) wheat were grown at seven locations in North Dakota in 1998 in a randomized complete‐block experimental design with three replicates at each location. Unreduced SDS‐soluble glutenins of flour were fractionated by multistacking SDS‐PAGE into different sized glutenin polymers, followed by SDS‐PAGE and imaging densitometry to determine the quantitative variation of HMW glutenin subunits. SDS‐insoluble glutenin polymers also were examined for their quantitative composition of HMW glutenin subunits. The results showed that the percentage of HMW glutenin subunits was significantly affected by growing locations. The quantity of HMW glutenin subunits in SDS‐insoluble glutenins was significantly and positively correlated with loaf volume. SDS‐insoluble glutenin polymers had a higher percentage of HMW glutenin subunits than did SDS‐soluble glutenins. SDS‐insoluble glutenin polymers in flour were positively and significantly correlated in proportions of both total and individual HMW glutenin subunits in total SDS glutenins. SDS‐insoluble glutenin polymers also were positively and significantly correlated with the combined proportion of HMW glutenin subunits 2* + 5. The results of this study indicated that either subunit 2* or 5 might be more important in forming a greater quantity of larger SDS‐insoluble glutenin polymers than other subunits. SDS‐insoluble glutenin polymers from different cultivars or locations could have different quantities of HMW glutenin subunits in their composition. SDS‐insoluble glutenin polymers with more HMW glutenin subunits might be larger sized than those with less HMW glutenin subunits. Environment significantly influenced the quantitative variation of HMW glutenin subunits, which in turn affected the size distribution of glutenin polymers, and hence breadmaking quality. 相似文献
7.
N. Radovanovic S. Cloutier D. Brown D. G. Humphreys O. M. Lukow 《Cereal Chemistry》2002,79(6):843-849
A total of 162 doubled haploid (DH) lines were produced from a cross between Triticum aestivum L. ‘AC Karma’ and line 87E03‐S2B1 to study the genetic contribution of high molecular weight (HMW) glutenin subunits to gluten strength. HMW glutenin subunit composition of each DH line was determined by SDS‐PAGE. The population was grown in the field at one location in 1999 and at three locations in 2000. Gluten strength and dough mixing properties were measured by mixograph test and SDS‐sedimentation test. Variance components were estimated for each measurement to determine the variability contributed by HMW glutenin subunits. Results indicated significant environmental impact on tested mixograph parameters, SDS‐sedimentation volumes and grain and flour protein concentration. Significant main effects of Glu‐1D loci encoded subunits were obtained for mixograph development time, energy to peak, slope after peak, and first minute slope. Lines containing 5+10 combination of subunits had higher values for mixograph development time and energy to peak, while slope after peak and first minute slope were lower as compared with 2+12 containing lines. Low intergenomic interactions were observed for bandwidth energy (BWE), total energy (TEG), and SDS‐sedimentation test, involving B and D genomes only. A portion of the genetic variability for gluten strength was accounted for overexpression of Bx7 subunit originating from the cultivar Glenlea derived line 87E03‐S2B1. There was no significant effect of Glu‐A1 encoded subunits on any of the tested parameters. Estimated genetic variability for gluten strength contributed by Glu‐B1 and Glu‐D1 encoded HMW glutenins was 55% for mixing development time and 51% for energy to peak. 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.
M. Eugenia Steffolani Gabriela T. Prez Pablo D. Ribotta M. Cecilia Puppo Alberto Edel Len 《Cereal Chemistry》2008,85(1):39-43
The effect of transglutaminase (TG) on glutenin macropolymer (GMP) properties could help to understand changes in bread quality. The aim of the present study was to analyze modifications in GMP and dough properties caused by TG addition. Transglutaminase introduced cross‐links to gluten proteins, mainly high molecular weight glutenins. This effect modified the protein structure and markedly increased dough strength. These changes in the structure of glutenins increased SDS solubility and decreased GMP content and GMP storage modulus. However, TG increased GMP particle size, notably at higher doses. TG affected rheological characteristics of dough in that increasing TG doses decreased tan δ, and increased G'. In all the studies conducted, the TG increased GMP polymer size, but contrary to what was expected, this increase did not involve an increase in GMP content. These results confirmed the effect of TG on dough quality and the great differences found with different TG doses. 相似文献
10.
Three cultivars of hard red spring (HRS) wheats with identical high molecular weight (HMW) glutenin subunit composition (5+10 type, Glu-D1d) but different dough properties and breadmaking quality were used in this study. The synthesis and accumulation characteristics of different protein fractions during grain development were examined. Samples were collected at three-day intervals from anthesis to maturity between day 10 to day 37. The nonreduced SDS-extractable glutenin aggregates of developing grains were characterized by a multistacking SDS-PAGE procedure to obtain information on the size distribution and polymerization of glutenin aggregates. The HMW to low molecular weight (LMW) glutenin subunit ratio was determined for its relationship to polymerization of the various glutenin aggregates of different molecular sizes. Glutenin proteins were quantified using an imaging densitometer. In addition, albumins and globulins, α- and β-gliadins, γ-gliadins, and ω-gliadins were separated by capillary zone electrophoresis. The results indicated that albumins-globulins, gliadins, and glutenins in developing grains were present at 10 days after anthesis or earlier. Albumin-globulins decreased in proportion, while gliadins increased in proportion during grain development. Polymerization of glutenin aggregates occurred 10 days after anthesis or earlier and increased significantly throughout the grain-filling period until maturity. Larger aggregates of glutenin increased in proportion, while smaller ones decreased in proportion during grain development. Ratio of polymers to monomers increased significantly from day 10 to day 22 of grain development and then remained constant until grain maturity. Glutenin polymers arrived at their maximum in proportion to total SDS-extractable proteins or monomers at day 22 after anthesis while the molecular size of these polymers continued to increase, as indicated by a rapid increase in proportion of HMW to LMW glutenin subunits. Significant differences were found in accumulation rates of glutenin polymers among the three cultivars. Cultivars Kulm and Grandin, with better breadmaking quality, appeared to have greater rates of accumulation and HMW subunit synthesis or formation of larger polymers than did Sharp, a cultivar with poorer quality. Significant differences were found among the three cultivars in the proportion of albumins-globulins and gliadins during grain development. However, no significant differences were found among the cultivars in the proportion of albumins-globulins, α-, β-, γ-, and ω-gliadins at grain maturity. Varietal differences in breadmaking quality were due mainly to the differences in glutenin polymers such as ratio of polymeric to monomeric proteins, molecular size distribution, and ratio of HMW to LMW glutenin subunits among wheat cultivars of 2*, 7+9, and 5+10 subunit types. The better breadmaking cultivars might be characterized with higher proportions of glutenins and greater proportion of HMW subunits in total SDS-extractable proteins than the poorer quality cultivar. However, more genotypes need to be examined. 相似文献
11.
Gluten proteins from two cultivars of hard red spring (HRS) wheat with good and poor breadmaking quality were fractionated into 13 fractions by sequential extraction with dilute hydrochloric acid. Each subfraction was characterized by multistacking (MS) SDS‐PAGE under nonreducing conditions, followed by imaging densitometry. The glutenin polymers from the origins of MS‐SDS‐PAGE were analyzed by SDSP‐PAGE under reducing conditions to determine the composition of high and low molecular weight subunits. The results showed that fractions differed significantly in glutenin‐to‐gliadin ratios and in the size distribution of glutenin polymers. The earlier precipitated fractions were composed of more gliadins but fewer glutenin polymers. However, the glutenin polymers gradually increased in their relative quantities with the residue having the largest glutenin‐to‐gliadin ratio. The size distribution of glutenin polymers differed significantly from early precipitated to later fractions. The relative quantities of glutenin aggregates at the 4% origins increased significantly. The ratio of high molecular weight (HMW) to low molecular weight (LMW) glutenin subunits increased significantly from early to intermediate fractions. Between the two cultivars, significant differences were found in the ratio of HMW to LMW glutenin subunits and quantity of SDS insoluble glutenin polymers in the residue fraction with the better breadmaking quality cultivar ND706 having a greater ratio than the cultivar Sharp. It was concluded that the size distribution of glutenin polymers played an important role in determining the differences in breadmaking quality between the good and poor HRS wheat cultivars. 相似文献
12.
Ten glutenin fractions were separated by sequential extraction of wheat gluten protein with dilute hydrochloric acid from defatted glutenin‐rich wheat gluten of the Canadian hard red spring wheat (HRSW) cultivar Glenlea. The molecular weight distribution (MWD) of 10 different soluble glutenin fractions was examined by multistacking SDS‐PAGE under nonreduced conditions. Also, the subunit composition of the different glutenin fractions was determined by SDS‐PAGE under reduced conditions. The MWD of the fractions (especially HMW glutenins) varied from fraction to fraction. From early to later fractions, the MWD shifted from low to high. The early extracted fractions contained more LMW glutenin subunits (LMW‐GS) and less HMW glutenin subunits (HMW‐GS). The later extracted fractions and the residue fraction contained much more HMW‐GS (2*, 5, and 7 subunits) than the early extracted fractions. The trend in the amounts of 2*, 5, and 7 subunits in each fraction from low to high matched the extraction solvent sequence containing from lower to higher levels of HCl. The influence of glutenin protein fractions from the extra‐strong mixing cultivar, Glenlea, on the breadmaking quality of the weak HRSW, McVey, was assessed by enriching (by 1%) the McVey base flour with isolated glutenin protein fractions from Glenlea. The mixograph peak development times and loaf volumes of enriched flour were measured in an optimized baking test. The results indicated that the higher content in Glenlea glutenin of HMW‐GS with higher molecular weight, such as 2*, 5, and 7, seem to be the critical factor responsible for the strong mixing properties of Glenlea. Our results confirmed that subunit 7 occurred in the highest quantity of all the HMW‐GS. Therefore, it seems that the greater the content of larger molecular weight glutenin subunits, the larger the glutenin polymers and the stronger the flour. 相似文献
13.
Flour mill streams obtained by milling grain of 10 bread wheat cultivars grown in the Skopje region of Macedonia were analyzed for rheological and breadmaking quality characteristics and for composition of gliadins and HMW‐GS. The objective of this study was to examine the relationships between the composition of gluten proteins and breadmaking quality, as well as to determine the importance of gluten proteins for technological quality of flour mill streams. The grain was milled in an experimental mill according to a standardized milling procedure, with three break and three reduction passages. The addition of two vibratory finishers in the milling scheme enabled better separation of bran. A small‐scale baking method for evaluation of the breadmaking properties was developed, and electrophoretic methods including acid‐PAGE and SDS‐PAGE were used to determine the composition of the gluten proteins. There were significant differences in the degree of dough softening of individual and total flour fractions of the flour mill streams for cultivars with different alleles from six loci, for farinograph water absorption from seven loci, and for bread loaf volume and crumb quality score from six loci. The Glu‐1 quality scores for the wheat cultivars investigated were 3–9 and proved to be a useful indicator of breadmaking quality. The novel feature of the investigation related to the breadmaking potential of the flour mill streams compared with straight‐run flours. 相似文献
14.
The influence of nitrogen (N) fertilizer application rate (0 vs. 70 vs. 140 kg N ha–1) and timing (early = at sowing vs. late = at sowing and before heading) on the amount of protein groups, amount and size distribution of mono‐ and polymeric proteins, and gluten strength was investigated in one set of wheat cultivars (Triticum aestivum L.). Due to their genetic background, the cultivars had different protein concentrations and gluten strengths. Despite this, all of them reacted similarly on rate and timing of nitrogen application. The rate of nitrogen fertilizer increased the variation in protein concentration, gluten strength, and also the variation in most of the investigated protein components. Higher nitrogen fertilizer rate increased protein concentration, decreased gluten strength, and increased the total amount of glutenins and gliadins as well as the amounts of most mono‐ and polymeric proteins. Timing of fertilizer did not influence protein concentration. The gluten strength and the relations of proteins were changed by the timing of fertilizer. Early nitrogen feritilizer applications led to higher gluten strength and a higher percentage of total unextractable polymeric protein in the total polymeric protein and large unextractable polymeric protein in the total large polymeric protein, compared to late nitrogen fertilizer applications. 相似文献
15.
Nondeveloped, partially developed with shear and extensional deformations, and developed doughs represent different stages of dough development. To understand the relationship between gluten proteins and dough rheology, this study used disulfide‐sulfhydryl analyses, gel filtration chromatography, SDS‐PAGE, acid polyacrylamide gel electrophoresis (A‐PAGE), and densitometry to examine proteins in the four types of doughs mentioned. Free sulfhydryl content was the lowest in native flour and nondeveloped dough, and the highest in partially developed doughs, while a reverse trend was observed for disulfide content. For each flour sample, the protein elution profile from gel filtration chromatography shifted with the level of dough development. With respect to the smallest sized molecules, native flour had the most, followed by nondeveloped, partially developed, and then developed doughs. SDS‐PAGE and A‐PAGE exhibited similar protein patterns among the same chromatographed protein fractions of each native flour and its different doughs. Densitometric data showed that the amount of high molecular weight (HMW) glutenins increased and the amounts of low molecular weight (LMW) glutenins, gliadins, and albumins/globulins decreased with progressive stages of dough development. In conjunction with previously published results, indications are that the increase in the size and the amount of HMW glutenins is related to the strength of dough and the amount of protein matrix present in the dough. 相似文献
16.
N. P. Ames J. M. Clarke J. E. Dexter S. M. Woods F. Selles B. Marchylo 《Cereal Chemistry》2003,80(2):203-211
Field studies were conducted over three years at two locations in Saskatchewan, Canada, to determine the effect of nitrogen fertilizer on protein quantity and protein strength in 10 cultivars of durum wheat (Triticum turgidum L. var. durum) representing a range of gluten strength. Increasing nitrogen fertilizer resulted in increased protein content in all cultivars across environments. Cultivars were clearly differentiated on the basis of gluten strength using a gluten index (GI), SDS sedimentation (SDSS), alveograph indices of overpressure (P) and deformation energy (W), mixograph energy to peak (ETP), and mixograph bandwidth energy (BWE) at all fertilizer levels. Variable cultivar response to nitrogen fertilizer was observed only for protein content, GI, and alveograph W. The nature of the cultivar‐by‐fertilizer interaction for GI suggested that the conventional strength cultivars would benefit more from nitrogen fertilizer than the extra‐strong types, which showed no change or slight decreases in GI with nitrogen fertilizer despite an increase in total gluten. SDSS increased with nitrogen fertilizer, following similar trends as protein. Gluten strength rankings of the cultivars by SDSS were maintained with increased fertilizer. Fertilizer had little effect on alveograph P, mixograph ETP, and mixograph BWE. Overall, GI values were more stable across increasing levels of nitrogen fertilizer and resultant increased protein content compared with SDSS, mixograph development time, and alveograph W and L, suggesting it is a good test for estimating intrinsic gluten strength for cultivars with a wide range of protein content. 相似文献
17.
Two biotypes of an Australian wheat cultivar, Warigal, differing only in the Glu-D1 high molecular weight (HMW) glutenin subunits 5+10 and 2+12 were used in this study. The objective was to examine the effects of nitrogen fertilization and allelic variation at the Glu-D1 locus on the characteristics of glutenin polymers. Unreduced proteins containing the SDS-soluble glutenins and the other protein classes were analyzed by multistacking SDS-PAGE which separates the glutenin into six distinctly different-sized aggregates. The results showed that nitrogen fertilization significantly increased protein quantity, ratio of polymers to monomeric proteins, and sizes of SDS-soluble glutenins. Nitrogen fertilization affected the proportions of HMW subunits in both SDS-soluble and SDS-insoluble glutenin polymers and the ratio of x to y subunits in SDS-insoluble glutenin polymers. Nitrogen fertilization, however, did not cause a significant change in ratio of SDS-soluble to SDS-insoluble glutenins. SDS-insoluble glutenins had a greater ratio of HMW to LMW and x to y subunits, especially with a higher increase of 1Dx subunits, than SDS-soluble glutenins. The HMW/LMW subunit ratio and the x/y subunit ratio may be used to predict sizes of glutenin polymers. The biotype with 5+10 subunits had a greater x/y subunit ratio in the SDS-insoluble glutenins than the 2+12 type. A greater proportion of subunit 5 was formed than subunit 2 in the SDS-insoluble glutenin polymers. Both nitrogen fertilization and allelic variation at Glu-D1 loci could affect the characteristics of glutenin polymers. 相似文献
18.
The aim of this study was to isolate high‐molecular‐weight (HMW) gliadins from wheat flour and to characterize the protein components that contribute to HMW gliadins. Wheat flour Akteur was extracted with a modified Osborne procedure, and the fraction soluble in 60% ethanol (total gliadins) was separated by gel‐permeation HPLC, yielding three fractions, GP1–GP3. GP1 (21.5%) consisted of oligomeric HMW gliadins, GP2 (15.2%) of ω5‐gliadins, and GP3 (63.3%) of ω1,2‐, α‐, and γ‐gliadins. Two‐dimensional SDS‐PAGE of HMW gliadins showed that interchain disulfide bonds were present in HMW gliadins. The molecular mass distribution of HMW gliadins determined by gel‐permeation HPLC was in a range from 66,000 to 680,000 with an average degree of polymerization of 13. Reduced HMW gliadins were further separated by preparative reversed‐phase HPLC into four subfractions (RP1, RP2, RP3, and RP4), which were characterized by SDS‐PAGE and semiquantitative N‐terminal sequencing. HMW gliadins of the wheat flour Akteur contained all types of gluten proteins: 48% low‐molecular‐weight glutenin subunits, 18% γ‐gliadins, 13% α‐gliadins, 9% ω1,2‐gliadins, 8% HMW glutenin subunits, and 4% ω5‐gliadins. We postulate that the existence of HMW gliadins can be explained by the presence of terminators, which interrupt the polymerization of glutenin subunits during biosynthesis and lead to polymers of limited size (oligomers) that are still soluble in aqueous ethanol. 相似文献
19.
Three samples of Nekota (hard red winter wheat) were milled, and six mill streams were collected from each sample. The 18 mill streams were analyzed separately as well as recombined to form three patent flours. The methods of multistacking (MS)‐SDS‐PAGE and SDS‐PAGE were used to separate the unreduced SDS‐soluble glutenins and the total reduced proteins, respectively. The separated proteins were quantified by densitometry. The quantity of unreduced SDS‐soluble proteins was significantly different among the mill streams at the 4% (largest molecular weight polymeric glutenins) and at the 10 and 12% (smaller molecular weight polymeric glutenins) origins of the MS‐SDS‐PAGE gels. The quantities of total HMW‐GS, LMW‐GS, 2*, 7+9, and 5+10 subunits and the ratio of HMW‐GS to LMW‐GS in polymeric protein samples isolated using preparative MS‐SDS‐PAGE and in total reduced protein extracts were significantly different among mill streams. The quantities of HMW‐GS, LMW‐GS, 2*, 7+9, and 5+10 subunits from total reduced proteins were positively and significantly correlated with loaf volume. The quantities of glutenin subunits (both HMW‐GS and LMW‐GS) from unreduced SDS‐soluble proteins were positively or negatively correlated with loaf volume at the various MS‐SDS‐PAGE gel origins but the levels of correlation were not significant. These results showed that the glutenin protein composition was different among the various mill streams and demonstrated that electrophoretic analysis of the proteins in these fractions is a useful tool for studying the variation in functional properties of flour mill streams. 相似文献
20.
Twenty‐seven durum wheat genotypes originating from different geographical areas, all expressing LMW‐2 at Glu‐B3, and five bread wheats were evaluated for flour mixing properties, dough physical characteristics, and baking performance. Gluten polymeric composition was studied using size‐exclusion HPLC of unreduced flour protein extracts. As a group, durum wheats had poorer baking quality than bread wheats in spite of higher protein and total polymer concentrations. Durum wheats exhibited weaker gluten characteristics, which could generally be attributed to a reduced proportion of SDS‐unextractable polymer, and produced less extensible doughs than did bread wheats. However, substantial variation in breadmaking quality attributes was observed among durum genotypes. Better baking performance was generally associated with greater dough extensibility and protein content, but not with gluten strength related parameters. Extensibility did not correlate with gluten strength or SEHPLC parameters. Genotypes expressing high molecular weight glutenin subunits (HMW‐GS) 6+8 exhibited better overall breadmaking quality compared with those expressing HMW‐GS 7+8 or 20. Whereas differences between genotypes expressing HMW‐GS 6+8 and those carrying HMW‐GS 7+8 could only be attributed to variations in extensibility, the generally inferior baking performance of the HMW‐GS 20 group relative to the HMW‐GS 6+8 group could be attributed to both weaker and less extensible gluten characteristics. 相似文献