青海高原春小麦HMW—GS等位基因变异及其对面团流变学特性的作用

为了给青海高原春小麦改良提供资料。分析了青海育成和国内外引进的125个春小麦品种(系)的HMW—GS等位基因变异。并测定了其中58个品种(系)在青海高原环境下的面团流变学特性。结果表明：(1)参试春小麦品种(系)的HMW—GS存在广泛的变异。Glu—A1位点出现3个等住基因，Glu—B1住点出现5个等住基因，Glu—D1位点出现4个等位基因；共出现了22种HMW—GS组合形式。其中1.7 8.2 12和N，7 8，2 12组合类型出现频率最高。并发现了个别罕见的变异类型，如2 10，10。(2)亚基组合类型对沉淀值、形成时间、稳定时间、评价值等品质性状影响较大，对籽粒蛋白质含量、出粉率和面粉吸水率的影响不显著。试验还表明，HMW—GS组成与面粉的筋力有密切关系。     

微量沉淀值和麦谷蛋白亚基组成对面包烘烤品质的效应

为快速高效地改良中国小麦品种的面包烘烤品质,将72份冬小麦品种(系)于2000～2001年度分别种植于河南郑州和山东济南,分析了它们的蛋白质品质和面包烘烤品质,评价了蛋白质含量、微量沉淀值及高、低分子量麦谷蛋白亚基组成对面包烘烤品质的作用.结果表明,总体上中国冬小麦品种的蛋白质含量和微量沉淀值中等偏高,面包烘烤品质则较差,品种间差别较大.高、低分子量麦谷蛋白亚基的等位变异与面包烘烤品质密切相关,Glu-Dl位点具有5 10亚基和Glu-B3位点具有h亚基的品种,其面包各烘烤品质参数均显著优于具有其他亚基的品种,而Glu-B3j亚基(即1B/1R易位)对微量沉淀值、比沉淀值和面包体积、颈高、外观、质地、结构、色泽、评分等品质参数均具有较大的负向作用.沉淀值对非1B/1R易位系面包体积和评分的作用远大于蛋白质含量的贡献,而单位蛋白质含量的沉淀值即比沉淀值对1B/1R易位系的面包体积和评分更重要.在育种中应针对非1B/1R易位系和1B/1R易位系采用不同的品质改良策略,对非1B/1R易位系可考虑通过提高沉淀值,对1B/1R易位系则应考虑通过提高比沉淀值来改良面包烘烤品质.     

新疆小麦品种籽粒性状、磨粉品质及其关系的研究

为给新疆冬、春小麦品种籽粒性状与磨粉品质改良提供参考依据,以30个新疆冬小麦品种和36个新疆春小麦品种为试验材料,研究了新疆小麦品种籽粒性状、磨粉品质特性及其两者的关系。结果表明,新疆冬、春小麦品种籽粒性状基本相近,各有优劣,主要差异表现在硬度大小不同,冬小麦品种的硬度（47.1）小于春小麦品种（61.8）;冬小麦品种的出粉率和黄度分别高于和低于春小麦品种,说明冬小麦品种的磨粉品质优于春小麦品种。新疆本地育成冬小麦品种的籽粒硬度（51.8）小于春小麦品种（62.9）,出粉率高于春小麦品种,灰分、红度和黄度也高于春小麦品种。综合来看,新疆本地育成春小麦品种的籽粒性状略优于冬小麦品种,磨粉品质优于冬小麦品种。相关分析表明,新疆冬、春小麦籽粒硬度与破损淀粉率呈极显著正相关,与L*值呈极显著负相关;籽粒蛋白含量与面粉灰分呈显著正相关。说明籽粒硬度和籽粒蛋白含量与新疆小麦磨粉品质关系最为密切。总之,在新疆小麦籽粒性状与磨粉品质改良中,应以籽粒硬度和面粉色泽改良为重点,同时也要提高新疆小麦籽粒蛋白含量和出粉率。     

宁夏引黄灌区冬小麦谷蛋白亚基组成和1BL/1RS易位分析及品质性状研究

为全面了解宁夏引黄灌区冬小麦品质概况,为冬小麦品质改良和粮食生产提供理论依据。选用冬小麦主栽品种、亲本材料和高代品系30份。用SDS-PAGE分析了其中18份材料的HMW—GS、LMW—GS组成和1BL／1RS易位系分布状况。并对23个冬小麦品种的营养与加工品质进行了研究。结果表明,2#、7＋9、2＋12、Glu-A3a、Glu-A3c、Glu-B3h和Glu—B3j在宁夏引黄灌区冬小麦中分布较广,1BL／1RS易位系分布相当普遍。分布频率为27．8％。参试品种的籽粒硬度、面粉PPO活性、SDS沉淀值、形成时间、稳定时间和评价值的变异范围较大,变异系数分别为25．37％、33．68％、21．42％、26．58％、43．95％和29．31％。多数冬小麦品种（系）的千粒重、出粉率和湿面筋含量低于对照宁春4号。而蛋白质含量、SDS沉淀值、吸水率和稳定时间优于宁春4号。供试品种（系）中。HMW-GS品质评分、籽粒硬度、蛋白质含量、SDS沉淀值均较高,并且不含1BL／1RS易位系的有烟优361、济麦20、鲁875067和923—9等,可用于宁夏引黄灌区冬麦品质改良。     

小麦高分子量谷蛋白亚基与品质性状的关系

为了明确甘肃省小麦的高分子量麦谷蛋白亚基(HMW—GS)组成及其对品质的贡献率，选用30个甘肃省近几年推广品种、后备品系及优良亲本，分析了它们的HMW—GS、品质性状及其之间的关系。结果表明：(1)适宜于甘肃省种植和利用的小麦品种(系)的HMW—GS类型较丰富，但与优质有关的亚基(2^*，17 18，14 15，5 10)分布频率较低；(2)Glu—A1和Glu—D1位点的等位变异与品质性状关系密切，特别是Glu—D1位点含有5 10亚基的品种比含有2 12亚基的品种沉淀值高、稳定时间长，且稳定时间的差异达到极显著水平。其余品质性状如湿面筋含量、粗蛋白含量等之间的差异不显著。     

相同HMW—GS组合小麦品种的主要品质指标分析

为了研究具有相同高分子量谷蛋白亚基（HMW—GS）组合的小麦品种间是否存在品质差异,采用SDS-PAGE电泳技术从200多份黄淮冬麦区新育成的小麦品种（系）中筛选鉴定出12个具有1／7＋9／2＋12HMW—GS组合的小麦品种（系）,并对其主要品质性状进行分析。结果表明,12个具有相同HMW—GS组合（1／7＋9／2＋12）小麦品种的面粉蛋白质含量、湿面筋含量和Zeleny沉淀值均存在差异,其中蛋白质含量和湿面筋含量差异不大,但Zeleny沉淀值差异较大（平均为30．2mL,变幅为23．3～45．9mL,变异系数为22．4％）。在面团流变学特性中除吸水率外,形成时间、稳定时间和评价值均有较大变异,形成时间平均为3．7min,变幅为2．2～7．4min,变异系数为36．9％;评价值平均为57．9,变幅为36～149,变异系数为53．0％;稳定时间变异最大,平均为3．7min,变幅为1．6～15、1min,变异系数为99．8％。表明具有相同HMW—GS组合的小麦品种的主要品质性状仍存在较大的差异。     

春小麦品种高分子量谷蛋白亚基与品质的关系

选用甘肃省河西地区种植的57个春小麦品种。在已经分析HMW—GS组成的基础上。测定了这些品种的理化特性和面团流变学特性。对这些品种的HMW—GS和品质性状的变异情况、HMW—GS与品质性状之间的关系、具有不同HMW—GS的品种间品质的差异和同-HMW—GS品种间的品质差异进行了研究。结果表明，Glu-Ⅰ位点的亚基总评分与面筋指数、沉淀值、面团变形功、面团形成时间及稳定时间呈显著或极显著正相关；HMW—GS数目的多少与其品质优劣有关，亚基数目越多，面粉筋力越好；采用不同品质指标评价小麦HMW—GS对品质的贡献，结果表明以变形功的评价排序的意义更明确。     

新疆春小麦籽粒性状与磨粉品质及其关系研究

为给新疆春小麦籽粒性状和磨粉品质的遗传改良提供理论依据,对386份新疆春小麦材料(55个地方品种、207个自育材料和124个引进材料)的籽粒性状与磨粉品质及其关系进行了研究。结果表明,不同来源春小麦材料的籽粒性状和磨粉品质各有优劣。386份供试材料的千粒重为37.48 g,容重为737.76 g·L~(-1),籽粒硬度为54.71,粒径为2.88 mm,籽粒蛋白含量为15.95%,出粉率为53.06%,灰分为0.54%,L~*值为96.86,a~*值为-1.16,b~*值为9.83。整体而言,籽粒蛋白质含量、L~*值较高;籽粒硬度较低,a~*值和b~*值较高,三者的变异系数较大,分别为22.26%、25.86%和15.67%,具有较好的改良潜力。籽粒性状与磨粉品质关系密切,其中千粒重、粒径与灰分含量呈极显著负相关,籽粒硬度、籽粒蛋白含量与灰分含量呈显著正相关,千粒重、粒径与L~*值呈显著负相关,与a~*值呈显著正相关,籽粒硬度与a~*值呈显著负相关,容重、粒径与b~*值呈显著或极显著正相关。昌春3号、伊春4号、中作8131、新春26号、新春33号等可用于新疆春小麦籽粒性状和磨粉品质改良的优选品种(系)。     

小麦磨粉品质的高分子量麦谷蛋白亚基评分系统研究

为了给优质小麦选育和栽培提供一定的参考，选用100个春小麦品种测定了其高分子量麦谷蛋白亚基（HMW—GS）以厦出粉率、降落数值、面粉白度和面粉黄度等4项磨粉品质，通过数量化理论及统计学鉴评方法研究了HMW—GS与小麦磨粉品质的关系，得到了4个多元回归方程（决定系数均在0．97以上），能准确预测4项小麦磨粉品质；建立了针对不同小麦磨粉品质的HMW-GS评分系统。总体来看，1、2^＊、7、5＋10亚基和10亚基对小麦磨粉品质而言，属于优质亚基。但对不同的品质指标，各亚基的贡献不尽相同：10亚基有利于出粉率的提高；1亚基除了能改善面粉黄度外，还可以提高降落数值；5＋10亚基是公认的优质亚基，2＋10、2＋12亚基是公认的劣质亚基，但对于面粉白度而言，2＋10和2＋12亚基评分较高，而5＋10亚基评分反而最低。因此，不能仪根据某一项指标对亚基进行评分。     

甘肃省冬小麦农家品种与改良品种的HMW GS变异及品质效应比较

为了解甘肃冬小麦农家品种和改良品种HMWGS变异及品质效应,为小麦品质改良和亲本选用提供依据,采用SDSPAGE法和近红外反射光谱法检测340份品种的HMWGS和其中252份的沉淀值、蛋白质和湿面筋含量。结果表明,340份品种在Glu1位点共有14种亚基变异,34种亚基组合形式。GluA1位点共有3种变异,亚基缺失（null)的频率最高,1和2^*亚基出现的频率改良品种（36.9%）比农家品种（12.0%）高;GluB1位点共有7种变异,7+8亚基出现的频率最高,改良品种比农家品种降低36.1个百分点;GluD1位点有4种亚基变异,2+12亚基出现频率最高,改良品种比农家品种降低11个百分点,5+10亚基的频率改良品种较农家品种提高17.6个百分点。含5+12亚基的农家品种及含14+15亚基的改良品种综合品质较优。从供试改良品种中筛选出在2个以上基因位点具有优质亚基的品种46个,其中10个品种在3个位点上都具有优质亚基。     

Impact of Starch Properties on Hearth Bread Characteristics. II. Purified A- and B-granule Fractions

Using the nine different wheat varieties, sixteen different flours were blended to achieve two protein levels 11 and 13%. Mixing characteristics of the flours were analysed by Farinograph and Mixograph. Thermal properties of flour were measured by differential scanning calorimetry (DSC). Starch gelatinisation, pasting viscosity, and gelation properties were assessed by a Rapid Visco-Analyser (RVA). Hearth bread loaves were produced from the flours using a small-scale baking method. The results from the analyses of flour were related to the properties of hearth bread loaves by multivariate statistical methods. The Partial Least Squares Regression (PLS) model (Model 1) obtained using results from grain and flour analysis (no starch analysis included) as X – matrix explained 70% of the total variance in hearth bread characteristic form ratio. If flour-pasting properties were included in the PLS1 model (Model 2) the explained variance increased to 77%. The model obtained including the DSC parameters of wheat flour explained 76% of the total variance in form ratio (Model 3). This emphasises the importance of starch in wheat flour and that it is possible to find wheat flour starch quality parameters in addition to protein quality that is important for hearth bread quality. No good models were obtained for hearth bread characteristics loaf volume and weight.     

黄淮冬麦区强筋小麦品种的产量及品质分析

为了解当前黄淮冬麦区强筋小麦品种的产量和品质表现,选用9个近年来黄淮麦区育成、在河南省大面积推广种植的强筋小麦品种,种植于河南的郑州和泛区,按AACC或国标的方法对其蛋白质和淀粉品质进行分析。结果表明,供试强筋小麦品种的产量显著低于高产对照品种周麦18;有5个品种的有效穗数显著高于周麦18,有3个品种与周麦18差异不显著;分别有1个品种的穗粒数、千粒重与周麦18差异不显著,其余品种均显著低于周麦18。说明黄淮冬麦区强筋小麦品种的穗粒数和千粒重有待提高。分析各品种的品质指标,对于湿面筋含量,有5个品种在两个试点均达国标,有2个品种在一个试点达国标;弱化度、面包体积、面包评分等反映面筋质量的品质指标均表现为郑州点优于泛区点;弱化度、面包体积在2个试点的差异达极显著水平;面包评分在2个试点的差异达显著水平。含5+10亚基的品种中,非1BL/1RS易位品种的烘焙品质显著优于1BL/1RS易位品种。郑麦366、师栾02-1、新麦26的麦谷蛋白亚基构成和面包烘焙品质均较优。郑麦366、矮抗58的峰值黏度较高,淀粉糊化特性较好,适合制作优质面条。     

Phytate negatively influences wheat dough and bread characteristics by interfering with cross-linking of glutenin molecules

The influence of added phytate on dough properties and bread baking quality was studied to determine the role of phytate in the impaired functional properties of whole grain wheat flour for baking bread. Phytate addition to refined flour at a 1% level substantially increased mixograph mixing time, generally increased mixograph water absorption, and reduced the SDS-unextractable protein content of dough before and after fermentation as well as the loaf volume of bread. The added phytate also shifted unextractable glutenins toward a lower molecular weight form and increased the iron-chelating activity of dough. It appears that phytate negatively affects gluten development and loaf volume by chelating iron and/or binding glutenins, and consequently interfering with the oxidative cross-linking of glutenin molecules during dough mixing. Phytate could be at least partially responsible for the weak gluten network and decreased loaf volume of whole wheat flour bread as compared to refined flour bread.     

Effect of physicochemical and empirical rheological wheat flour properties on quality parameters of bread made from pre-fermented frozen dough

The objective of this study was to examine the influence of flour quality on the properties of bread made from pre-fermented frozen dough. The physicochemical parameters of 8 different wheat flours were determined, especially the protein quality was analysed in detail by a RP-HPLC procedure. A standardized baking experiment was performed with frozen storage periods from 1 to 168 days. Baked bread was characterised for specific loaf volume, crumb firmness and crumb elasticity. The results were compared to none frozen control breads. Duration of frozen storage significantly affected specific loaf volume and crumb firmness. The reduction of specific loaf volume was different among the used flours and its behaviour and intensity was highly influenced by flour properties. For control breads wet gluten, flourgraph E7 maximum resistance and RVA peak viscosity were positively correlated with specific loaf volume. However, after 1–28 days of frozen storage, wet gluten content was not significantly influencing specific loaf volume, while other parameters were still significantly correlated with the final bread properties. After 168 days of frozen storage all breads showed low volume and high crumb firmness, thus no significant correlations between flour properties and bread quality were found. Findings suggest that flours with strong gluten networks, which show high resistance to extension, are most suitable for frozen dough production. Furthermore, starch pasting characteristics were also affecting bread quality in pre-fermented frozen dough.     

Interrelationships of Protein Composition, Protein Level, Baking Process and the Characteristics of Hearth Bread and Pan Bread

Baking performance of hearth bread and pan bread were investigated using 10 wheat varieties with variable protein quality. For most varieties, samples were selected at two protein levels, approximately 11 and 13% (d.m.). The effects of flour quality on loaf characteristics were different for hearth bread compared to pan bread, where both protein quality and protein content affect loaf volume positively in an optimised baking test. Hearth bread is more complex as both the form ratio and loaf volume are critical external characteristics. When using fixed proving time, the form ratio was positively affected by dough resistance and mixing peak time at high speed mixing, and negatively affected by dough extensibility. Dough resistance and mixing peak time correlated strongly to the HMW glutenin composition, whereas dough extensibility was related to protein content. In contrast to the form ratio, loaf volume was positively affected by dough extensibility, whereas protein quality had no significant effect. This was seen both for doughs produced at optimal mixing time at high speed mixing (126 rev/min) and for doughs produced at fixed mixing times at low speed mixing (63 rev/min). When proving time was optimised to achieve a defined form ratio, flours of strong protein quality should be proved longer than flours of week protein quality, resulting in higher loaf volume for flours of the strongest protein quality. With respect to protein content, the positive effect of protein content on loaf volume was counteracted due to reduced proving time when aiming for a defined form ratio.     

Extensional Flow Studies of Wheat Flour Dough. I. Experimental Method for Measurements in Contraction Flow Geometry and Application to Flours Varying in Breadmaking Performance

An experimental method is reported for extensional measurements on wheat flour doughs in contraction flow geometry. In this method the transient stress under constant extension rate was measured, followed by stress relaxation measurement after cessation of flow. Four different wheat cultivars (with large differences in bread volume) were used to evaluate the usefulness of the method and to find how different parameters relevant to baking quality could be extracted from the data. The plot of transient viscosity against time showed the effect known as strain hardening, appearing at a Hencky strain roughly independent of the strain rate but differing between the wheat varieties. The relaxation rate curves for the four wheat varieties were similar except at the highest strain rate, 7·40 s⁻¹. It was decided in the following case study to use the highest strain rate, 7·40 s⁻¹and to extract three parameters from the stress growth plot and three parameters from the stress relaxation rate plot. In the case study, flours of 17 wheat varieties were mixed in the Mixograph to maximum resistance before being subjected to the contraction flow measurement. The six parameters extracted from each wheat flour dough measurement, together with the corresponding protein content, Zeleny value, and bread volume, were evaluated by multivariate analysis. A model for predicting the bread volume from the contraction flow parameters explained 94·6% of the variation in bread volume, while a model with Zeleny values and protein contents included explained 97·2%.     

Can bread wheat quality be determined by gluten index?

In recent years, the Israeli wheat industry has suffered from quality problems that endangered the possibility of growing bread wheat in Israel. In addition to relying upon grain protein and test weight, the Israeli wheat market has therefore begun using the gluten index (GI) test method. To shed new light on wheat grain quality determinations, wheat grain samples were analyzed for GI and other quality parameters such as dry and wet gluten, SDS-sedimentation, and loaf volume. In many cases, low-GI grains exhibited good dough and bread quality. This could be attributed to the difference in GI values of the wheat versus the corresponding flour. Hence, milling plays a major role in GI determination. Furthermore, grain and white flour GI values did not correlate with other accepted quality parameters, such as SDS-sedimentation and loaf volume. Therefore, it is suggested that the GI be used with caution, and that the addition of other methods can improve wheat quality determination.     

Genetic and Environmental Effects on Puroindoline-a and Puroindoline-b Content and their Relationship to Technological Properties in French Bread Wheats

Grain hardness (GHa) in hexaploid wheat (Triticum aestivum L.) is a major factor of end use quality. The variation of texture has been related to the Hardness locus, closely linked with the puroindoline-a (PIN-a) and puroindoline-b (PIN-b) genes. In order to study the role of puroindoline content in texture variation, the quantity of puroindolines was determined. Puroindoline-a (PIN-a) and puroindoline-b (PIN-b) content was determined and a total of 11 bread making parameters were obtained from 40 bread wheat cultivars grown in four experimental locations. The 11 parameters were significantly influenced by the genotype whereas location did not significantly affect PIN-a or PIN-b content and loaf volume. PIN-b and grain hardness displayed the highest heritability coefficients (both 0.88). PIN-a and PIN-b content were not correlated with grain protein content (Prot) and grain hardness in hard and soft wheat types. In soft samples PIN-(a+b) content was negatively correlated, with loaf volume in two locations. Multiple regression analyses, carried separately for soft and hard types, revealed that PIN-b content explained variation of dough strength (W) and loaf volume, however their influence was mostly significant in soft types. For each location, from 22 to 91% of the phenotypic variation of strength and loaf volume was explained by combining up to three flour traits. Protein content, PIN-b and the average score of high molecular weight glutenin subunits (HMW-GS) were frequently introduced by multiple regression (without GHa) as explanatory variables of strength and loaf volume. These results strengthened the significant role of PIN-b in breadmaking (loaf volume), and indicated that biochemical factors other than puroindolines are involved in the grain hardness variation.     

Dough mixing characteristics measured by Mixsmart software as possible predictors of bread making quality in three production regions of South Africa

South Africa has three wheat production regions, the winter rainfall region where spring wheat is planted; the summer rainfall where winter and intermediate wheat is cultivated; and the irrigation region where spring wheat is grown. The aim of this study was to determine dough mixing characteristics as measured by Mixsmart^® software in these three regions over seasons and locations, and to relate this to important quality characteristics. In the winter rainfall area Mixsmart characteristics were very poor predictors of baking quality, especially of loaf volume, flour protein content and wet gluten content. The best predictors of loaf volume in this region were flour protein content and wet gluten content, which were highly interrelated. In the irrigation area, midline peak value and midline right value were very good predictors of flour protein content, gluten content and loaf volume. Midline peak value was highly correlated with protein content in both the irrigation and summer rainfall areas and was a better predictor than peak time of baking quality. The ideal would be to select several parameters from the mixograph and use them in a multivariate statistical analysis to obtain a more accurate prediction of loaf volume in the irrigation and summer rainfall areas.     

Wheat Bread Quality as Influenced by the Substitution of Waxy and Regular Barley Flours in Their Native and Extruded Forms

The substitution of wheat flour with barley flour (i.e. native or pretreated/extruded) reduced the loaf volume. Depending on the barley variety and flour pretreatments, the colour and firmness/texture of the bread loaves were altered. Amongst the barley breads prepared from native flours (at 15% barley flour substitution level), Phoenix had higher loaf volume and lower crumb firmness than Candle. However, amongst the barley breads prepared from extruded flours, CDC-Candle had higher loaf volume and lower crumb firmness than Phoenix. The lower loaf volume and firmer crumb texture of barley breads as compared with wheat bread may be attributed to gluten dilution. Also, the physicochemical properties of barley flour components, especially that of β-glucan, can affect bread volume and texture. β-glucan in barley flour, when added to wheat flour during bread making, could tightly bind to appreciable amounts of water in the dough, suppressing the availability of water for the development of the gluten network. An underdeveloped gluten network can lead to reduced loaf volume and increased bread firmness. Furthermore, in yeast leavened bread systems, in addition to CO₂, steam is an important leavening agent. Due to its high affinity for water, β-glucan could suppress the amount of steam generated, resulting in reduced loaf volume and greater firmness. In the present study, breads made with 15% HTHM CDC-Candle flour had highly acceptable properties (loaf volume, firmness and colour) and it indicated that the use of extruded barley flours would be an effective way to increase the dietary fibre content of barley breads.