Effects of α-, β-, γ- and ω-Gliadins on the Dough Mixing Properties of Wheat Flour

Gliadins were extracted from wheat and individual groups (α-, β-, γ-, ω-1 and ω-2) purified. The effects of the individual groups of gliadin on the mixing properties of doughs from low and high protein flours were measured on a 2-g Mixograph and a prototype microextension tester. The addition of all groups of gliadin resulted in a decrease in dough strength. The relative weakening effects were ω-1>ω-2≈α-≈β->γ- in the Mixograph, and γ->α-≈β-≈ω-2≈ω-1 in the Extensograph.     

The effects of sodium reduction on the mechanical properties of doughs made from flours with a range of strengths using a mixograph

To devise strategies for meeting Health Canada's target for reduced-sodium bread production, relationships between dough formula (i.e., red spring wheat flour, salt (NaCl) and water content) and dough mechanical properties were examined. Mixograph energy to peak (ETP), peak height (PKH), and peak bandwidth (PBW) were used to define changes in the properties of doughs induced by sodium reduction. ETP measurements indicated that dough strength characteristics were less responsive to sodium reduction as water content was increased. ETP was a good indicator of the cultivar-dependent response of doughs to sodium reduction, with doughs made from stronger flours being more sensitive to sodium reduction. According to ETP results, sodium reduction led to a decrease in flour strength discrimination. Sodium reduction at NaCl contents below ~1.5% led to more obvious changes in dough mixing characteristics (indicated by the ratio of PBW to PKH). Mixograph analyses of dough tolerance to sodium reduction will guide wheat breeding programs to select cultivars suitable for reduced sodium breadmaking.     

Improvement on Mixograph test through water addition and parameter conversions

To improve Mixograph testing effect, Farinograph measurements were adopted as a quality standard and changes in water absorption and parameter conversion in Mixograph test were explored. Comparative study showed that increasing water absorption to about 73% and converting original parameters to compound parameters in Mixograph tests significantly increased their predictive power for flour quality. These efforts also enabled the adoption of fixed water addition level in Mixograph test and simplified the test procedure significantly. With the success in parameter conversions, Mixograph test results were successfully described by Farinograph parameters, which allow breeders to compare and exchange test results easily. All these changes optimized the official method of Mixograph test with simplified procedure and enhanced reliability and made the Mixograph being the superior tool for quality assessment in wheat-breeding programs.     

从产量和品质性状的变化分析北方冬麦区小麦品种抗热性

培育抗热性强的品种对应对气候变化,保障小麦稳产性具有重要意义。选用北方冬麦区53份主栽品种和苗头品系,于2008—2009年度分别种植在北京、石家庄、衡水、安阳和泰安5点,各点设正常温度和塑料棚热胁迫处理。结果表明,千粒重可作为抗热性筛选的简易指标。农大189、CA0518和京冬8号的产量和千粒重在正常和热处理环境中均较高,抗热性好;衡观33和CA0736的产量在正常和热处理环境中均较高,但千粒重均表现中等,抗热性较好;农大211、石麦15、济麦22、农大3432和山农2149在正常环境中的产量和千粒重均较高,但在热处理环境中产量和千粒重均较低,抗热性差。53份品种按和面时间和峰值曲线面积可分为强筋、中强筋、中筋、中弱筋和弱筋5大类。热处理使所有类型材料的蛋白质含量和籽粒硬度增加,峰值带高、8min带高和8min带宽降低,并降低强筋、中强筋和中筋类型材料的和面时间与峰值曲线面积,增加中弱筋和弱筋类型材料的和面时间与峰值曲线面积。     

Effects of α-, β-, γ- and ω-Gliadins on the Dough Mixing Properties of Wheat Flour

Gliadins were extracted from wheat and individual groups (α-, β-, γ-, ω-1 and ω-2) purified. The effects of the individual groups of gliadin on the mixing properties of doughs from low and high protein flours were measured on a 2-g Mixograph and a prototype microextension tester. The addition of all groups of gliadin resulted in a decrease in dough strength. The relative weakening effects were ω-1>ω-2≈α-≈β->γ- in the Mixograph, and γ->α-≈β-≈ω-2≈ω-1 in the Extensograph.     

The gluten protein and interactions between components determine mixograph properties in an F6 recombinant inbred linepopulation in bread wheat

One hundred and sixty-eight F₆ recombinant inbred lines (RILs) derived from Chinese wheat cultivars, PH82-2 and Neixiang188, were used to determine the cumulative effects of HMW-GS and LMW-GS composition and quantity of gluten protein fractions on dough mixograph properties. A wide range of variation for all parameters in the RILs was detected. Major gene loci of HMW-GS were associated with variation in mixograph characters, but accounted for no more than 25.3% of the phenotypic variations. Glu-D1, together with Glu-B3, played the most important role in determining the properties. Additive effects of HMW-GS and LMW-GS showed major contributions to most of the variation of mixograph parameters, and epistatic effects were also important and could be counter to additive effects of individual loci. The quantity of gluten protein fractions, especially the quantity of glutenin, LMW-GS, and Glu-B3, showed highly significant correlations with most of the quality parameters, but the correlation coefficients were influenced by grain hardness, protein content, or both. Protein quality could be greatly improved through increasing the quantity of glutenin, while holding desirable composition of HMW-GS and LMW-GS alleles, with an appropriate ratio of quantity of glutenin to gliadin.     

宁麦9号及其衍生品种(系)揉混特性的关联分析

揉混特性是评价面团流变学特性的重要指标,影响面食产品的品质。宁麦9号曾是我国长江中下游小麦生产中大面积应用的优质软质小麦品种,而且以其为亲本育成了17个小麦品种。研究与宁麦9号揉混特性相关的分子标记可为该品种在软质小麦品种育种中的应用提供依据。以宁麦9号及其117个衍生品种(系)为材料,利用覆盖小麦全基因组的185对多态性SSR引物对其进行基因组扫描,并结合2009–2010和2010–2011生长季的揉混参数表型数据,应用混合线性模型(Mixed-linear Model, MLM)进行全基因组关联分析,发掘与其相关联的分子标记位点。共检测到13个与揉混参数相关联的标记位点(P<0.01),表型贡献率为5.71%~12.33%。其中,与和面时间关联的有3个,Xwmc594连续两年被检测到;与峰值高度关联的有3个;与峰值宽度关联的有2个,Xgwm299连续两年被检测到;与8 min带宽关联的7个中,4个(Xwmc11、Xbarc320、Xbarc110和Xgwm577)连续两年被检测到。此外,Xwmc594和Xgwm577同时与和面时间、8 min带宽相关联。以上6个稳定的关联位点均对相应揉混参数起负向调控作用,其连锁的分子标记有望应用于以宁麦9号为亲本的软质小麦遗传改良。     

Relationships between dough strength,polymeric protein quantity and composition for diverse durum wheat genotypes

Five different Glu-B1 HMW-GS patterns were identified among a collection of diverse durum wheat genotypes grown in 2001 in two locations in western Canada. The durum wheat lines exhibited a wide range of dough and gluten strength characteristics as measured by alveograph and 2 g mixograph parameters, gluten index (GI), and protein composition as measured by unextractable polymeric protein (UPP) content and the ratio of high-molecular weight (HMW) glutenin subunits (GS) to low-molecular weight (LMW) GS. HMW-GS subunits patterns represented within the genotypes were 6+8, 7+8, 7+16, 14+15 and 20. Two of the genotypes expressed Glu-A1 HMW-GS 2* in combination with other HMW-GS. Approximately 95% of the durum genotypes were γ-gliadin 45 types. Analysis of variance indicated that genotype was a greater source of variation in all measurements than was growing location, with the exception of protein content which showed less variation contributed by genotype and more contributed by location than for other quality parameters. UPP was strongly associated with all strength measurements. All of the γ-gliadin 42 types were low in UPP and weak. Among the γ-gliadin 45 types, those possessing HMW-GS 20 were typically in the lower half of the UPP and strength range. There was no clear evidence of an association between any of the other HMW-GS patterns and gluten strength. The majority exhibited HMW to LMW-GS ratios that were within the relatively narrow range of 0.15–0.25, yet there were wide variations in dough strength among genotypes within that range. Increasing proportions of HMW-GS resulting in ratios of greater than 0.30 were generally associated with weak dough and gluten and low UPP content.     

我国冬小麦品种谷蛋白聚合体的分布及其与和面仪参数的关系

利用GMP的丙醇--双缩脲改良测定法,对我国冬麦区124份有代表性的冬小麦品种和品系的谷蛋白聚合体进行了测定,系统探讨了谷蛋白聚合体与和面仪参数的关系.结果表明:(1)我国小麦品种面粉谷蛋白大聚合体(GMP)含量的分布范围在1.70%～6.60%之间,平均含量为3.87%;GMP在面粉蛋白质中所占的比例(GMP/Pr)平均为31.21%;面粉可溶性谷蛋     

小麦面团揉混特性的遗传变异及与其他品质性状的相关性

为了解小麦种质资源的品质状况,并给小麦品质改良提供参考,以来源于国外及国内不同麦区的230个小麦品种(系)为材料,研究小麦面团揉混特性参数的变异和分布特点及与其他品质性状的相关性.结果表明,参试品种(系)面团揉混参数间均存在极显著差异(P＜0.01),除峰值高度、尾高和8 min尾高外,其他揉混参数的变异系数均在30％以上.同时,在本试验中,国外引进品种的面团揉混参数均高于国内品种,多数参数的差异达到显著水平(P＜0.05);来源于北方春麦区的品种(系)面团揉混参数值较高,来源于华南冬麦区的品种(系)各揉混参数均最低,且部分参数达显著差异(P＜0.05).同时筛选出一批揉混参数值极高或极低的材料,可作为小麦品质育种的优选亲本.相关性分析结果表明,多数揉混参数与籽粒硬度、蛋白含量、吸水率、形成时间、稳定时间、粉质质量指数和干、湿面筋含量呈显著或极显著相关.