The role of a low molecular weight glutenin fraction in the cooking quality of durum wheat pasta

Durum wheat glutenin fractions, composed of two low molecular weight proteins DSG-1 and DSG-2 (durum wheat (Triticum durum Desf) sulphurrich glutenin fractions) were extracted from semolina samples using a low concentration of Na tetradecanoate after extracting albumins, globulins and gliadins. DSG proteins have a high? SH plus S? S content. A highly significant correlation was found between the ? SH plus S? S content of this DSG-rich fraction and the cooking quality of pasta (0.63, P <0.01 with firmness and 0.86, P <0.001 with the state of the surface of the cooked pasta) and this seems to be a functional relationship. The use of acetic acid at various molarities showed the presence of high molecular weight glutenin fractions with differing solubility properties. In this respect, differences were found between varieties which are placed in the same group according to the classification of durum wheats based upon the composition of high molecular weight glutenin subunits.     

The HMW glutenin subunit composition of Canadian wheat cultivars and their association with bread-making quality

The proteins of 70 Canadian-grown wheat cultivars were fractionated by SDS-PAGE to determine their HMW glutenin subunit composition. On the basis of previously established relationships between individual subunits and measures of bread-making quality, Glu-1 scores were calculated for 67 cultivars. The three cuhivars Chinook, Cypress and Supreza were found to contain novel HMW glutenin subunits previously uncatalogued. The Glu-1 scores accounted for 59–69% of the variation in bread-making quality of these cultivars whereas flour ash accounted for none. The implications of these results to wheat breeding programmes are discussed.     

Wheat protein composition and properties of wheat glutenin in relation to breadmaking functionality

The unique breadmaking properties of wheat are generally ascribed to the visco-elastic properties of its gluten proteins. While monomeric gluten proteins (gliadin) show viscous behavior, polymeric gluten proteins (glutenin) are elastic. The unique elasticity of glutenin results to a large extent from its polymeric nature. Glutenin is a highly heterogeneous mixture of polymers consisting of a number of different high- and low-molecular-weight glutenin subunits linked by disulfide bonds. Although glutenin obviously is the major polymeric protein in wheat, other polymeric proteins occur as well. Their importance in breadmaking may be underestimated. Nevertheless, variations in both quantity and quality of glutenin strongly determine variations in breadmaking performance. Structural features of different classes of glutenin subunits are described. Variations in glutenin quality may result from variations in its (1) structure, (2) size distribution, and (3) subunit composition. Some hypotheses on glutenin structure and current insights into the role of glutenin size distribution are evaluated. Finally, different ways in which variation in glutenin composition may directly or indirectly (by affecting glutenin structure and/or size distribution) influence glutenin quality are discussed.     

The relationship between HMW glutenin subunit composition and the bread-making quality of British-grown wheat varieties

Based on previous work, which related individual HMW glutenin subunits to bread-making quality by genetical analysis, quality scores were assigned to each of the commonly occurring subunits. The grain proteins of 84 home-grown wheat varieties were fractionated by SDS—PAGE to determine their HMW glutenin subunit composition. The quality scores of each of the subunits were summed to create a Glu-1 quality score for each variety. The results indicated that 47-60% of the variation in the independently established bread-making qualities of this set of varieties could be accounted for by variation in HMW subunits of glutenin. The presence or absence in the varieties of a translocated chromosome, which consisted of the long arm of 1B and the short arm of 1R from rye, was also established because of its known association with poor bread-making quality. A correction factor was applied to the Glu-1 quality score of those varieties that contained the 1 BLURS chromosome. The variations in the rye-adjusted Glu-1 quality scores were compared with those of the bread-making qualities of the varieties, and the proportion of variation in quality accounted for was raised to 55-67%. The Glu-1 quality score and the biscuit-making qualities of the same set of varieties were negatively related. The results are discussed in relation to future strategies recommended to wheat breeders for developing new varieties with improved bread-making quality.     

小麦及其面粉品质对馒头品质的影响

综合分析了小麦与面粉的蛋白质品质、淀粉品质、酶、脂类物质等对馒头品质的影响。     

小麦胚芽粉对馒头品质的影响

研究了小麦胚芽粉加入量对馒头品质的影响。测定不同小麦胚芽粉加入量下制得的馒头的比容、白度、硬度以及感官评分等并观察其变化,结果显示,随着小麦胚芽粉含量的增加,馒头的白度和比容均呈下降趋势,而硬度呈现先平缓后上升的趋势,馒头的感官评分则是先增大后减小,在加入量为6%时所制得的馒头的感官评分最高。     

Blocked thiols in glutenin and protein quality

It has already been suggested that when glutenin chains are synthesised, two cysteine residues on each chain preferentially form interchain disulphide bonds (SS) resulting in linear arrays of polypeptide chains. Presumably steric factors stop the growth of a molecule eventually, leaving each terminal chain with a free SH group. It is now postulated that the free SH groups later react with low molecular weight (mol. wt) thiols and SS compounds, which also break some interchain bonds by SS interchange so reducing the average mol. wt of the glutenin. Terminal SH groups and the halves of each broken SS become blocked by low mol. wt compounds. Therefore, if the quantity of glutenin-bound low mol. wt thiols (end-blockers) bound to glutenin could be measured it would enable the number of glutenin molecules to be calculated and hence a number-average mol. wt. When six wheats spanning the normal range of baking quality were tested, glutenin-bound half-cystine and glutathione residues were eventually found, but no SH groups could be detected. The number-average number of chains per glutenin molecule (proportional to mol. wt) was correlated with intrinsic viscosity of glutenin and with loaf volume per gram of loaf protein, thus supporting the hypothesis. It is suggested that the main aim of reducing the native thiol content of flour with improvers is to limit degradation of glutenin molecules. If the hypothesis should be confirmed it may be advantageous to breed wheats with low contents of thiols and active disulphides in the grain, since their quantities may largely account for glutenin mol. wt and, in turn, protein quality.     

Flour quality tests for selected wheat cultivars and their relationship to Arabic bread quality

Analytical and rheological parameters were established for flours from nine selected wheat cultivars, each covering a range of protein contents. Arabic and pan breads were baked from these flours and baking quality was determined. Wheat cultivars were found to differ in their suitability for Arabic bread production. Within cultivars the relationship between protein content and Arabic bread score was best described by a quadratic equation. Traditional flour quality tests do not adequately describe the flour quality requirements for Arabic bread as clearly as for pan bread. Ranges and optimum values for a number of parameters can be set to describe flours most likely to be suited to the production of Arabic bread. However, for reliable evaluation of baking quality for Arabic bread, flours fitting the prescribed range must be test baked.     

Variation in type and relative amounts of the high molecular weight glutenin subunits in dutch wheat varieties

The high molecular weight glutenin (HMWg) subunit genotypes and amounts of the individual subunits of 38 Dutch wheat varieties were determined. In winter wheat varieties, HMWg subunit alleles that, in general, have been shown to be related to a poor bread-making quality predominated. In spring wheat varieties, ‘high-quality’ alleles were most frequent. When examining the published HMWg subunit genotypes of British and German varieties a similar difference was found in HMWg subunit genotype between spring and winter wheats. Because bread-making quality of spring wheat varieties is, in general, superior to that of winter wheats, probably also because of the lower protein content of the latter, the two groups should be taken separately when studying the relation between HMWg subunit genotype and bread-making quality. There was a considerable variation in relative amounts of allelic HMWg subunits and of subunits encoded by different genes (at the same or homeologous loci). Between varieties with the same HMWg subunit genotype, relative amounts of identical subunits differed only slightly. Some of these differences may reflect differences in gene expression, but it is not known to what extent differences in genetic background or differences in gene promoter are involved. There were differences in relative amounts of HMWg subunits encoded by alleles at the Glu-Bl locus. Here, an increase in relative amounts coincided with an increase in contribution to bread-making quality of an allele.     

小麦蛋白质的特性与面条品质

面条是中国、日本、韩国等国家的主要食品之一,其品质关系到多数人的健康。现介绍面条的品质评价、小麦蛋白质的组成特性以及小麦蛋白质的含量、组成和特性与面条之间的关系。     

小麦面筋蛋白组成、结构和功能特性

小麦面筋蛋白(俗称谷朊粉)主要由麦醇溶蛋白和麦谷蛋白组成,其蛋白组成和结构是影响小麦面团特性和烘焙品质重要因素。该文对小麦面筋蛋白组成、结构进行综述,以更清楚了解其结构对功能性影响。     

Variation in bread-making quality: effects of weather parameters on protein concentration and quality in some Swedish wheat cultivars grown during the period 1975–1996

Two spring and two winter wheat cultivars were investigated for bread volume, grain protein concentration and mixogram index. Data for the weather conditions—mean day temperature per month, precipitation per month, and sun hours per month—were collected for the same period. Relationships between the quality factors were studied as well as relationships between these factors and weather conditions. The bread volumes varied from 910 to 1415 ml, and from 630 to 1067 ml for the spring and winter wheats, respectively. The grain protein concentrations were between 11.1 and 14.9% for the spring wheats, and between 10.6 and 16.7% for the winter wheats. Mixogram indexes varied from 110 to 156, and from 89 to 139, for spring and winter wheats, respectively. A strong correlation was found between the bread-making quality and the grain protein concentration and quality. The grain protein concentration and mixogram index accounted for 19% and 15% of the variation in bread volume, respectively. The climatic variables influenced on bread volume, and grain protein concentration and quality. The temperature, specially during the grain filling period, was the most important weather parameter, explaining 34% of the variation in grain protein concentration and 49% of the variation in mixogram index in spring wheat. The influence of the weather on the quality parameters, were more complex in the winter wheats. © 1998 Society of Chemical Industry.     

Interaction between nitrogen and sulfur by foliar application and its effects on flour bread‐making quality

BACKGROUND: Optimization of nitrogen (N) and sulfur (S) nutrition of wheat influences the bread‐making quality of grain. This study was conducted to determine whether the application of N and S in winter wheat at anthesis stage during two field trials could influence the absorption and distribution of N and S in grain and flour bread‐making quality RESULTS: The incorporation of ¹⁵N and ³⁴S tracers in various plant parts (leaves, stems, spikes) was determined by isotopic ratio mass spectrometry coupled with an elemental analyser (EA‐IRMS). The effects of foliar fertilization on percentage of ¹⁵N and ³⁴S recovery in various plant parts, grain yield, flour protein content, and dough properties were investigated after a combination of treatments: N (urea), S (micronized elemental S) and NS (both urea and micronized elemental S). Nitrogen (70–80%) and S (35–55%) were quickly assimilated during the days following application. Sixty days after application, 42–68% N and 6–12% S were recovered in the grain. When N and S fertilizers were applied simultaneously, N and S recoveries (68% and 12%), N/S ratios (11–14), flour protein content (115 g kg^?1) and dough strength (310 × 10^?4 J), swelling (21.8 mmH₂O) and extensibility (96.4 mm) were increased. CONCLUSION: A synergistic effect between the foliar applied N and S fertilizers appears to increase N and S assimilation in grain and may improve bread‐making qualities. Copyright © 2007 Society of Chemical Industry     

我国优质面包小麦品种的现状和建议

本文根据７０年代以来我国进行的３次小麦品质的评定结果分析,指出当前我国小麦品质的现状、存在问题及发展对策,以期推动我国优质小麦品种的研究与开发。     

微细化麦麸膳食纤维制备及其对面制品品质影响

该文报道以麦麸为原料制备膳食纤维工艺,确定最佳技术条件并制备微细化麦麸膳食纤维;且在面粉中分别添加5%、8%、10%、12%和15%麦麸膳食纤维配制膳食纤维面粉。按我国传统工艺技术制备不同麦麸膳食纤维添加量的馒头和中式面条样品,并据行业标准分别进行品质评价;结果表明,添加麦麸膳食纤维使馒头体积及感官指标评价得分均呈下降趋势,当其添加量为8%时,馒头总体品质评价得分高于80%;麦麸膳食纤维添加量不超过5%的麦麸膳食纤维面条,其感官品质指标与空白样面条接近,都可被市场所接受。     

The effects of bread‐making process factors on Australian sweet lupin‐wheat bread quality characteristics

Factorial experimental design was used to investigate the effects of: sponge proofing time (min), sponge and dough mixing time (min), final proofing time (min), final proofing temperature (°C) and baking time (min) on Australian sweet lupin‐wheat bread physical attributes. Factorial models show that bread specific volume was positively associated with sponge and dough mixing time (P = 0.01) and baking time (P = 0.02). Crumb area was positively associated (P = 0.01) with sponge and dough mixing time. Final proofing time positively influenced cell wall thickness (P < 0.01) and cell diameter (P < 0.01) but negatively affected number of cells (P < 0.01). Cell diameter was positively associated with baking time (P = 0.04), whilst number of cells was negatively influenced by sponge and dough mixing time (P = 0.01). Instrumental springiness was positively associated with sponge and dough mixing time (P = 0.02). Sponge and dough mixing and baking times were the two most significant process parameters affecting the bread physical quality and hence should be optimised.     

黄淮麦区小麦馒头加工品质影响因素的研究

选用黄淮麦区南部主栽品种和近几年国家审定的品种共42个,研究其馒头加工品质与小麦品种品质性状的关系及影响馒头品质的主要小麦品质性状.结果表明:42个小麦品种馒头总评分75.8分,达到80分以上的占24%;适合制作优质馒头的品种有豫农035、郑育麦029、周99133、周麦16、花培5号、周麦19、偃展4110、漯4518、豫麦34和丰舞981.馒头总评分与面粉白度和亮度呈极显著正相关,与面粉灰分、直链淀粉和膨胀势呈显著负相关.对主要小麦品质性状进行协调选择是选育优质馒头小麦品种的关键     

小麦粉中磷酸盐本底含量检测研究

小麦粉是日常生活和许多食品加工行业常用的食品原料,而磷酸盐在其加工制品生产加工过程中起着重要的膨松、抗氧化等作用,国标要求用GB/T 5009.87 - 2003《食品中磷的测定》第三法对小麦粉及其加工制品进行磷酸盐含量检测,但小麦粉的磷酸盐本底含量对小麦粉加工制品磷酸盐检测结果的影响,目前国内外未有相关报道.为了确认国标法测定市售小麦粉磷酸盐含量时,小麦粉本底对结果的影响,测定了华北、东北地区10个自磨小麦粉磷酸盐含量,结果显示自磨小麦粉的磷酸盐检测值达到了2.55g/kg～3.59g/kg,此检测值已经接近国家卫生标准规定的磷酸盐限量值5g/kg.市售小麦粉及其制品的磷酸盐检测量实则为小麦粉本底磷酸盐含量及磷酸盐添加剂的总量.因此在小麦粉磷酸盐检测时有必要考虑本底值的影响,以上检测结果为小麦粉生产加工过程中磷酸盐添加限量值提供科学数据.     

小麦谷蛋白溶胀指数与面团特性及面条品质相关性分析

选用30种小麦,通过谷蛋白溶胀指数(SIG)与面团特性及面条品质的相关性研究,进而评价谷蛋白溶胀指数在预测蛋白质品质中的应用.结果表明:SIG与面团品质参数形成时间、稳定时间、弱化皮、拉伸曲线面积具有显著相关性,相关系数分别为0.537,0.547,-0.516,0.469;SIG20与面条品质参数最佳蒸煮时间、咀嚼性、弹性具有显著相关性,相关系数分别为0.455,0.477,-0.521,与硬度具有相关性,相关系数为0.334.谷蛋白溶胀指数比其他3种预测方法更简单,相关性更好,更适合中国小麦蛋白质品质预测,可以用于指导品质育种、谷物化学研究、面制食品加工.