Effect of heat on rheology,surface hydrophobicity and molecular weight distribution of glutens extracted from flours with different bread-making quality

Gluten was extracted from flours of several different wheat varieties of varying baking quality. Creep compliance was measured at room temperature and tan δ was measured over a range of temperatures from 25 to 95 °C. The extracted glutens were heat-treated for 20 min at 25, 40, 50, 60, 70 and 90 °C in a water bath, freeze-dried and ground to a fine powder. Tests were carried out for extractability in sodium dodecyl sulphate, free sulphydryl (SH) groups using Ellman's method, surface hydrophobicity and molecular weight (MW) distribution (MWD) using field-flow fractionation and multi-angle laser light scattering. With increasing temperature, the glutens showed a decrease in extractability, with the most rapid decreases occurring between 70 and 90 °C, a major transition in tan δ at around 60 °C and a minor transition at 40 °C for most varieties, a decrease in free SH groups and surface hydrophobicity and a shift in the MWD towards higher MW. The poor bread-making variety Riband showed the highest values of tan δ and Newtonian compliance, the lowest content of free SH groups and the largest increase of HMW/LMW with increasing temperature. No significant correlations with baking volume were found between any of the measured parameters.     

Migration of gluten under shear flow as a novel mechanism for separating wheat flour into gluten and starch

This paper describes a novel principle for the separation of wheat flour into starch and gluten in a concentrated medium. The process is based on the use of simple shear flow in a cone-and-cone device. The separation takes place in two steps. Initially, local segregation of gluten and starch phases occurs, leading to formation of macroscopically visible gluten patches distributed throughout the dough. This local segregation can be understood by considering the dough as a visco-elastic matrix containing an inert filler (starch). Further shearing leads to aggregation of those patches and migration (large-scale separation) towards the apex of the cone. As a result, the wheat dough is separated into a protein-poor fraction, containing less than 4% protein, and a protein-rich fraction containing almost 50% protein on a dry weight basis. However, under the process conditions used, upon a very long shearing, a redistribution of the aggregated gluten structures in the starch phase was observed, demonstrating a processing limit for the separation performance. Compared to traditional processing, the separation process presented shows opportunities for producing high quality gluten accompanied with significant water savings. Considering the fact that simple shear flow in steady rate is less harmful to gluten quality, such a separation process could benefit gluten quality.     

A parametric and microstructural study of the formation of gluten network in mixed flour–water batter

The mechanism of gluten network development is still unclear and remains difficult to study since gluten network formation in bread dough is a rather quick process. In order to better characterize this dynamic event, we slowed down its kinetics by increasing the dough water content. During mixing, performed with a planetary mixer at variable mixing speeds and flour/water ratios, the torque was recorded. Common flours from wheat cultivars Orvantis, Caphorn and Isengrain, similar in composition and Farinograph parameters, were studied.     

模拟漆酶——Ⅰ.铜和弱碱性苯乙烯系阴离子交换树脂的复合物Cu-D370模拟漆酶催化漆酚氧化聚合成膜的红外光谱分析

用红外光谱研究了Cu-D370催化漆酚氧化聚合交联过程。在漆酚氧化聚合阶段,漆酚醌的特征吸收峰先涨后落;三取代苯型结构变为四取代联苯型;共轭双烯型结构变为共轭三烯型;并出现Ar-O-R型醚结构。所以漆酚的氧化聚合反应主要发生在苯环上。在漆酚聚合物交联阶段,双键数目迅速减少,共轭三烯也减少。而α,β—不饱和醛或酮以及不饱和醚型结构却逐渐增加。所以交联反应主要发生在漆酚的侧链上。这些结果表明,在漆酚氧化聚合交联过程中Cu-D370模拟了漆树酶和固定化漆树酶的催化作用。     

Effects of species and breeding on wheat protein composition

Wheat proteins are characterized by their excellent contribution to technological and baking properties. However, wheat proteins, especially gluten and amylase-trypsin inhibitors (ATIs), are also known to be responsible for a broad range of intolerances and allergies. In order to evaluate the impact of genetic variability on the composition of these functional but immunogenic protein types, a set of different Triticum species, including common wheat, durum, spelt, emmer and einkorn, was examined regarding ATI and gluten concentrations by RP-HPLC. Additionally, inhibition towards trypsin was determined by an enzymatic assay. Based on the results, none of the investigated wheat species can be considered to be less ‘immunogenic’. Nevertheless, due to the large variability of ATI and gluten amounts among different genotypes, the selection of less-immunoreactive wheat varieties for individuals that suffer from wheat related diseases (WRDs) might be possible. The impact of breeding was assessed for different varieties of common wheat from different breeding periods. Results revealed significant improvement of technologically valuable parameters such as the amount of high molecular weight (HMW) glutenins and the gliadin to glutenin ratio, but no increase in immunogenic proteins.     

不同筋性春小麦籽粒不同发芽程度下的品质分析

为了解穗发芽不同程度下对不同筋性春小麦品种品质的影响,该实验选取强筋小麦品种克春1号、克丰6号,中筋品种克旱16、克旱21,弱筋小麦品种新克旱9、克丰9为实验材料,利用人工智能气候培养箱模拟自然环境,人为控制种子发芽程度并测定相关数据,结果表明:出粉率在萌动状态下,强筋>中筋>弱筋,随着发芽程度的加深,出粉率并未表现出与小麦筋性相关的规律性;强筋粉降落值在萌动状态下,较正常状态下降幅度大于中筋粉,中筋粉大于弱筋粉;各筋性小麦品种其湿面筋含量、干面筋含量以及面筋指数均随发芽程度的加深,而降低。     

小麦面团粘度与面粉主要品质指标相关性研究

以山东省32个小麦品种为材料,进行面团粘度性状和蛋白质含量、面筋指数、面团流变学特性指标之间的相关性的研究。结果表明:(1)面团的粘度性状与面粉很多品质指标具有非常显著的相关性,可以使用面团粘度性状对面粉品质进行评价。(2)面团粘度与代表面团筋力强弱的品质指标都有非常显著的负相关,说明小麦面团粘度与小麦面团的筋力强度和面团的抗揉混强度之间具有非常显著的负相关性,表明降低面团的粘度,可以提高面筋质量、面团的抗揉混能力和面筋筋力强度。     

影响面条品质的小麦品质性状及其QTLs定位的研究进展

本文总结了国内外近几年关于面条品质的研究资料,对影响面条品质的小麦品质性状,包括蛋白质的含量、麦谷蛋白亚基组成、直链淀粉的含量、淀粉特性、Waxy蛋白、面筋的含量、沉淀值、面团的主要特性等进行了概述,对这些小麦品质性状在染色体上QTLs定位的研究情况进行了综述,以期为面条专用小麦的选育和我国面条加工业的发展提供科学的参考。     

Effect of tolerance to Septoria tritici blotch on grain yield,yield components and grain quality in Argentinean wheat cultivars

Septoria tritici blotch (STB) caused by Zymoseptoria tritici (Mycosphaerella graminicola) is a major disease of wheat worldwide due to significant losses in grain yield and quality. Disease tolerance is the ability to maintain yield performance in the presence of disease symptoms. Therefore, it could be a useful tool in the management of the disease. Although it is known, that there is disease tolerance to STB in some wheat cultivars, this aspect has not been studied among Argentinean cultivars. The aims of this study were to evaluate genotypic differences in tolerance to STB among Argentinean cultivars, considering the relationship between the area under disease progress curve or the green leaf area or the non-green leaf area duration with the grain yield. In addition the effect of the disease on yield, yield components, test weight, grain protein concentration, wet and dry gluten concentration and the influence of tolerance on these traits was investigated. Field experiments were carried out with ten cultivars in a split-split-plot design during 2010 and 2011. Inoculation treatments were the main plots and cultivars, the subplots. STB significantly reduced grain yield, their components, test weight and increase grain protein and gluten concentration. Cultivar Baguette 10 showed major tolerance to STB, indicated by a consistent low regression slope between the green area duration and yield, while Klein Chaja was non-tolerant due to a high regression slope. However, many cultivars such as Buck Brasil, Buck 75 Aniversario, Klein Escorpion and Klein Flecha had considerably similar regression slopes to Baguette 10, provided good levels of tolerance. Other cultivars presented no significant differences. The correlation coefficient between tolerance and grain yield potential was not significant, suggesting that tolerant high-yielding cultivars can be obtained. No relationship was found between quality group or tolerance with the increase in protein and gluten concentration due to STB either.