The influence of temperature extremes on some quality and starch characteristics in bread,biscuit and durum wheat

Environmental conditions during grain-fill can affect the duration of protein accumulation and starch deposition, and thus play an important role in grain yield and flour quality of wheat. Two bread-, one durum- and one biscuit wheat were exposed to extreme low (−5.5 °C for 3 h) and high (32 °C/15 °C day/night for three days) temperatures during grain filling under controlled conditions for two consecutive seasons. Flour protein content was increased significantly in one bread wheat, Kariega, under heat stress. Cold stress significantly reduced SDS sedimentation in both bread wheats. Kernel weight and diameter were significantly decreased at both stress treatments for the two bread wheats. Kernel characteristics of the biscuit wheat were thermo stable. Kernel hardness was reduced in the durum wheat for the heat treatment. Durum wheat had consistently low SDS sedimentation values and the bread wheat high values. Across the two seasons, the starch content in one bread wheat was significantly reduced by both high and low temperatures, as is reflected in the reduction of weight and diameter of these kernels. In the durum wheat, only heat caused a significant reduction in starch content, which is again reflected in the reduction of kernel weight and diameter.     

山西小麦品种籽粒硬度与主要品质性状研究

为明确山西省近十年育成小麦新品种的籽粒硬度和品质状况,利用单籽粒谷物特性测定仪(SKCS)、DA7200多功能近红外分析仪,对来自山西省近十年审定的56个小麦新品种的籽粒硬度、蛋白质含量、出粉率等指标进行了检测和分析。结果发现,山西省近十年审定的小麦品种中,硬质麦比例较高,为78%,混合型麦和软质麦比例较低,分别为12%和8%;硬度指数范围较宽,为16.33～78.93。经相关分析,小麦籽粒硬度指数与被测品质性状均呈正相关关系,其中,与出粉率、吸水率、最大拉伸阻力均呈极显著正相关(P0.01)。硬质麦的蛋白质含量、湿面筋含量、出粉率、沉降值等品质参数均显著高于混合型麦和软质麦。混合型麦的蛋白质含量、湿面筋含量、出粉率、沉降值等品质参数略高于软质麦。     

Physicochemical control of durum wheat grain filling and glutenin polymer assembly under different temperature regimes

Durum wheat is grown in the Mediterranean area where drought and high temperature frequently prevail and impact grain texture, composition and yield. The purpose of this work was to examine the effect of high temperature on grain development and final composition according to the timing of exposure. High temperature (up to 27.5 °C) was applied either during the linear grain filling or drying phases or during whole grain development. The dynamics of grain dry mass, water, glutenin polymers, and protein bodies during grain development were determined. Irrespective of high temperature timing, the arrest of grain filling was observed at 45.9% grain moisture content. At that point, starch granules included in endosperm cells reached their physical packing limit, limiting further deposits. HT applied before physiological maturity shortened the duration of grain filling and resulted in a significant increase in grain protein concentration and in the proportion of vitreous grain. Late formation of sodium dodecyl sulfate (SDS)-insoluble glutenin polymers below 32% grain moisture content was also favored. The ability of wheat storage protein to form a viscoelastic matrix embedding starch granules at the beginning of grain desiccation is proposed to be mandatory for gaining vitreous grains and a high proportion of SDS-insoluble glutenin polymers.     

The impact of Septoria tritici blotch in bread making quality among argentinean wheat cultivars

Septoria tritici blotch (STB), caused by Zymoseptoria tritici is a relevant foliar wheat disease worldwide. Several reports show the importance of STB on grain yield, their components and grain protein while little is known about its effect on the rheological properties of the wheat flour. The scarce literature found, only mentions the effect of the complex of foliar diseases on wheat quality, without individualizing the effect of the different pathogens separately. This study analyze the influence of increasing doses of inoculum of Zymoseptoria tritici, on the bread making quality of ten Argentinean wheat cultivars and its possible variation according to their quality group. The increase of inoculum concentration augmented the area under disease progress curve, decreased green flag leaf area duration and green leaf area duration. Cultivars K. Flecha and B.75 Aniversario had the lowest green flag leaf area duration causing higher reduction in grain filling period and higher reductions in P, indicating a lower gliadin/glutenin ratio. STB decreased P/L and E while L, W, D, SV and bread volume increased. Cultivars differed in rheological parameters according to their quality group. Gluten/protein relationship was significant in quality group 1 and non-significant in cultivars belonging to quality group 2 and 3.     

Molecular and biochemical impacts of environmental factors on wheat grain development and protein synthesis

Wheat grain yield and flour quality are strongly influenced by the effects of environment during grain fill. Environmental variables such as temperature, water and fertilizer influence the rate and duration of wheat grain development, protein accumulation and starch deposition in unique ways, and by different mechanisms. The effects of environment are superimposed on the intrinsic temporal patterns of gene expression during grain development. Integration of genomic and proteomic studies with developmental studies under controlled environmental conditions should make it possible to resolve complex patterns of gene expression during grain development, pinpoint key regulatory processes that are influenced by the environment, and reveal the molecular basis for environmental impacts on flour composition and quality.     

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。     

小麦三个品质性状微量检测方法的应用与评价

为探讨小麦育种中简单、可行和高效的品质选择指标,给小麦品质改良提供借鉴,对蛋白质含量、籽粒硬度和SDS沉淀值在本单位育种中的应用效果进行分析,结果表明籽粒硬度在不同基因型间的变异系数最大,在不同栽培条件和不同年份表现稳定,是有效、可靠的选择指标;SDS沉淀值与蛋白质含量、籽粒硬度均呈极显著正相关,在基因型间的变异较大,可作为一个能反映总体品质水平的选择指标;蛋白质含量在基因型间变异系数小,受环境影响大,用于早代选择效果不理想。品质育种中可根据籽粒硬度和SDS沉淀值进行初步选择。     

生态环境和播期对小麦籽粒产量及品质性状间相关性的影响

为了解不同生态环境下小麦产量与品质性状间的相关性及其受主要气候生态因子影响的变化规律,选用6个不同类型小麦品种在5个不同生态点分期播种。研究结果表明,小麦产量与品质性状间的相关性在不同品种、不同生态点与不同播期条件下存在显著差异。在6个小麦品种中,淀粉含量与面粉筋力间存在负相关关系。南京与姜堰两地在提高小麦品质时产量水平相应降低,而徐州、泰安与保定三地可以同步增加产量与蛋白质含量,但面粉筋力与烘烤品质不能保证相应的提高。晚播与早播、适播相比,蛋白质含量虽有所增加,但产量与其它品质性状都有所下降。随着灌浆期日均温的升高以及日较差的增大,蛋白质含量与沉淀值的相关系数减小;灌浆期间日较差越大,蛋白质含量与千粒重的相关性以及淀粉含量与沉淀值间的相关性均由负相关逐渐趋向于正相关;随灌浆期间的总日照时数增加,淀粉含量与沉淀值间的相关系数增大,由负相关逐渐变为正相关。因此,在小麦生态育种和调优栽培研究中,需要重视不同生态环境因子对小麦籽粒品质性状影响的不同步性。     

Durum wheat quality in Mediterranean environments: II. Influence of climatic variables and relationships between quality parameters

A total of 10 field experiments were carried out during the 1998 and 1999 growing seasons both in the north (Lleida) and the south (Granada and Jerez) of Spain. In Lleida and Granada, the experiments were conducted under both irrigated and rainfed conditions, while the Jerez trials were carried out only under rainfed conditions. Ten durum wheat genotypes were used in this study. Quality determinations consisted of 1000-kernel weight (TKW), test weight, vitreousness, ash content, protein content, pigment content and SDS sedimentation test. The influence of environment was predominant in determining the majority of quality traits, although pigment content and SDS volume were also genetically controlled. Environmental effects, studied by the mean of the climatic patterns influencing each trial, showed that total water input during grain filling appears to negatively affect grain quality by reducing test weight, grain vitreousness, and SDS volume, and by increasing ash content. High seasonal temperatures increased pigment content in the grain, but reduced TKW. From the correlations between quality parameters, an inverse and interesting relationship was found between protein content and SDS volume. Relationships between quality traits appear to be influenced to a certain extent by climatic conditions during grain filling and, depending on temperatures and water input during this phase, correlation coefficients can be either positive, negative or close to zero.     

不同土壤肥力下施氮量对小麦产量和品质的影响

为探究氮肥在不同土壤肥力条件下对小麦的增产提质效应,以强筋小麦品种丰德存麦5号和中筋小麦品种百农207为供试材料,分别在三个地点设置0、180、240和300 kg·hm^-2四个施氮水平,研究了不同施氮量对冬小麦籽粒产量和品质的影响。结果表明,地点、品种和施氮量均对小麦产量有显著影响,其中地点的影响最大,其次是施氮量,品种最小。在高肥力麦田,施氮量为180 kg·hm^-2时产量最高,中高肥力麦田和低肥力麦田均以施氮量为240 kg·hm^-2时产量最高。不施氮肥条件下,品质指标以高肥力麦田较高,低肥力麦田最低,表明基础肥力高有利于改善小麦品质。施用氮肥均显著提高了小麦籽粒中的蛋白质含量、蛋白质产量、沉淀值和湿面筋含量,延长了形成时间和稳定时间,各试验点表现一致。利用主成分分析将小麦品质性状转化为蛋白质因子和面粉粉质因子,结果表明,在低肥力麦田,施氮量对蛋白质因子的增强效应较大,在中高肥力麦田,施氮量能均衡提高蛋白质因子和粉质因子;在高肥力麦田,施氮量对小麦粉质因子的增强效应较大。不论土壤肥力高低,均以施氮量为240 kg·...     

Effect of temperature variation during grain filling on wheat gluten resistance

The objective was to investigate effects of natural variation in temperature during grain filling on wheat (Triticum aestivum L) gluten quality. Seventeen field trials with four different varieties were conducted during the years 2005–2008. Temperature records were obtained from automatic weather stations located near the field trial sites. The period from heading to yellow ripeness was divided into 20 sub-phases of equal thermal time units, and a last sub-phase comprising the seven days after yellow ripeness. Partial Least Squares Regression was used to relate the temperature records of the different sub-phases to gluten quality analysed by the Kieffer Extensibility test and the SDS sedimentation test.     

Winter wheat genotypes under different levels of nitrogen and water stress: Changes in grain protein composition

Hard white winter wheat with superior and consistent quality is preferable for Asian markets. This study investigated the combined influences of moisture deficit during grain-fill and N management on protein quality, dough rheological properties, and protein molecular weight distributions in soft and hard winter wheats. Genotypes were grown under an irrigation gradient and two N-fertilization levels. Grain polyphenol oxidase (PPO) activity, SDS sedimentation, and Mixograph analyses were evaluated. Flour protein composition was characterized using SE-HPLC. Moisture stress during grain-fill increased flour protein content. N fertilization increased flour protein content. No significant correlation was found between flour protein and PPO. Changes in protein composition were related to general increases in protein content, regardless if the result of reduced irrigation or increased fertilization rate. The percentage of monomeric proteins increased more than the polymeric proteins as flour protein increased. Similarly, SDS sedimentation volume increased as a function of protein content. As expected, subunit GluD1 5+10 was associated with larger sedimentation volume and higher dough strength in genotypes as compared to those with subunit GluD1 2+12. Biplot analyses showed that genotypes of similar protein quality and composition responded similarly to N and irrigation treatments.     

Molar fractions of high-molecular-weight glutenin subunits are stable when wheat is grown under various mineral nutrition and temperature regimens

Molar fractions of the high-molecular-weight glutenin subunits (HMW-GS) were determined for flour from bread wheat (Triticum aestivum L. cv Butte86) produced under 13 different combinations of temperature, water and mineral nutrition. Albumins, globulins and gliadins were removed from the flour by extraction with 0.3 M NaI in 7.5% 1-propanol. Total HMW-GS were recovered by extracting the remaining protein with 2% SDS and 25 mM DTT. Individual HMW-GS were then separated and quantified by RP-HPLC. Constant molar fractions for the five HMW-GS were maintained under all environmental conditions, despite large differences in duration of grain fill, total protein per grain, flour protein percentage, and total HMW-GS per grain. Similar molar fractions were found for five other US wheat varieties. The Bx7 subunit accumulated to the highest level at 30% of total HMW-GS. The Dx and Dy subunits were present in smaller but nearly equal proportions, 22% and 23%, respectively, and the Ax and By subunits were the least abundant, 14% and 12%, respectively. Although the amounts of HMW-GS per unit of flour are strongly affected by environment, the different subunits respond so similarly to external conditions that their final proportions appear to be determined mainly by genetic factors.     

不同品质类型小麦灌浆期旗叶Rubisco降解变化研究

为了解小麦籽粒蛋白品质的形成机制,以弱筋和强筋小麦为材料,研究了小麦灌浆期间旗叶叶绿素含量以及Rubisco （1,5二磷酸核酮糖羧化酶/加氧酶）降解的变化。结果表明,小麦灌浆期间不同品质类型品种旗叶叶绿素含量和Rubisco含量差异明显,弱筋小麦品种宁麦9号和扬麦15花后15~25 d旗叶叶绿素含量分别降低16.8%和19.6%,而强筋小麦品种郑麦9023和镇麦168花后15~25 d叶绿素含量下降幅度分别为52.8%和34.6%;旗叶灌浆期内肽酶活性呈先升高后降低的趋势,并且2个强筋品种花后5~25 d内肽酶活性始终高于2个弱筋品种;小麦旗叶Rubisco含量在开花后呈逐渐降低的趋势,但两个弱筋小麦品种旗叶中Rubisco含量始终高于两个强筋小麦品种。此外,扬麦15花后15～20 d才可以看出Rubisco亚基出现降解现象,郑麦9023在花后15 d就已经明显出现了Rubisco大亚基降解,说明强筋小麦郑麦9023旗叶较弱筋小麦扬麦15衰老早。     

我国小麦品质现状分析

为给小麦生产及粮食购销、加工企业提供小麦品种品质方面的信息,2003～2005年从全国各地征集了1334份小麦样品（包括369个品种）,对其籽粒品质、面粉品质、面团特性及加工品质进行了测定和评价。结果表明,在所测试的品质性状中,稳定时间的变异系数最高（83．28％）,其次为最大阻力、形成时间、拉伸面积、沉淀值、降落数值、延伸性、湿面筋和蛋白质含量,容重、出粉率和吸水率的变异系数较低（2．44％、2．84％、6．06％）。稳定时间、拉伸面积、形成时间、沉淀值、最大阻力等品质性状在品种间和年度间变化较大。与国家标准相比对,2003、2004和2005年测试样品中分别达到强筋和弱筋小麦国家标准主要指标的品种数为7、24、39个和2、6、12个。与农业部1986、1990、1994年三次面包品质测定结果相比较,我国强筋小麦的烘焙品质呈逐步改良趋势。     

灌水对冬小麦品质和产量的影响

为研究水分对冬小麦籽粒产量和品质的影响,选择鲁麦22和烟农15两个品种,在防雨棚池栽条件下设置了“越冬水＋拔节水＋挑旗水”（处理A）、“越冬水＋拔节水＋挑旗水＋灌浆水”（处理B）和“越冬水＋拔节水＋挑旗水＋麦黄水”（处理C）三种灌水处理,研充不同处理下的冬小麦品质和产量性状的变化.结果表明：（1）不同灌水处理对两个冬小麦品种品质性状的影响趋势一致。浇灌浆水的（处理B）对两品种的籽粒容重、出粉率、湿面筋含量、沉淀值和粉质仪指标均无明显影响,但浇麦黄水（处理C）后两品种籽粒的容重、出粉率、湿面筋含量、沉淀值均显著降低,粉质仪指标也显著变劣;（2）不同灌水处理对两个冬小麦品种产量性状的影响不同：鲁麦22的粒重和籽粒产量均以处理B最高,处理A次之,处理C最低;烟农15粒重和籽粒产量表现为处理A与处理B无显著差异,处理C则显著降低。     

我国春麦区部分小麦品种品质状况分析

1999年将 38份春小麦品种 (品系 )种植于内蒙古呼和浩特 ,对其磨粉品质和面包烘烤品质进行了评价。结果表明 ,我国春小麦品种的面包烘烤品质较差 ,不同地区品种间品质差异较大 ,辽宁和内蒙品种的磨粉品质和面包烘烤品质优于其它地区的品种。回归分析表明 ,蛋白质含量和单位蛋白质含量的面包体积决定了面包体积总变异的 99.9% ,硬度、沉淀值和吸水率对面包总分有重要作用。品种的出粉率主要取决于 1心槽路出粉率 ,2心和 1皮槽路出粉率对出粉率贡献也较大。高分子量麦谷蛋白亚基 (HMW GS)Glu A1和Glu D1位点的等位变异与品质性状密切相关。面包烘烤品质的改良应在分析HMW GS的基础上 ,将硬度作为选择指标之一 ,适当提高蛋白质含量 ,重点加强对沉淀值的选择     

Accelerated ageingof wheat grains: Part I- Influence on rheological properties of wheat flour

Natural ageing is defined as handling and storage of freshly harvested grain for several years under storage condition to achieve suitable flour quality after milling. Accelerated ageing of wheat which is obtained using higher temperature during a specific storage time under controlled relative humidity may improve the quality of wheat flour. The present study addresses the effect of accelerated ageing on the rheological properties of wheat flour produced by freshly harvested wheat. The process of accelerated aging was performed by three different factors including rise in wheat moisture content (16, 18 and 20% w/w), control of storage temperature (30, 40 and 50°C) and control of the storage time (2, 5 and 8 days) using a central composite design. After the grain milling, rheological properties of wheat flour of different treatments were studied. Results indicated that promoting the storage time to 8 days and temperature up to 40°C could improve rheological properties such as dough stability, dough development time and farinograph quality number. This phenomenon may be due to oxidation and rearrangement of disulfide bonds resulting in increasing strength and improving flour quality. Increasing moisture content and storing in higher temperatures resulted in weakening rheological properties.     

行距配置对高产冬小麦籽粒灌浆特性及淀粉和蛋白质积累的影响

为研究不同行距配置对小麦籽粒发育及淀粉和蛋白质积累的影响,以4个高产冬小麦品种为材料,在河南浚县农业科学研究所超高产攻关田研究了不同行距配置下小麦籽粒灌浆特性及淀粉、蛋白质的积累动态.结果表明,高产小麦籽粒中可溶性糖含量下降与淀粉含量的增加趋势基本吻合,宽窄行种植模式(S1)籽粒中可溶性糖含量较高,且转化利用较快,促进了籽粒淀粉积累.从行距配置看.周麦22籽粒蛋白质含量以等行距种植模式(S2)较高,偃展4110和矮抗58均以S1较高,而豫麦49-198在两种种植模式下无明显差异.籽粒灌浆速率、千粒重和产量则表现为豫麦49-198、周麦22和矮抗58均以S较高,而偃展4110以S2较高.灌浆模型分析表明,灌浆持续天数和最大灌浆速率出现时间是行距配置影响粒重的主要因素.