青稞和小麦醇溶蛋白和谷蛋白结构性质的比较研究

采用Osbron法分别提取青稞和小麦中的醇溶蛋白和谷蛋白,对这4 种蛋白质进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE）分析和红外光谱分析,并测定其表面疏水性、热稳定性、总巯基和二硫键含量。结果表明：醇溶蛋白在青稞蛋白质中的含量为16.96%,低于其在小麦蛋白质中的含量;谷蛋白在青稞蛋白质中的含量为47.83%,高于其在小麦蛋白质中的含量,但经SDSPAGE分析发现青稞中高分子质量谷蛋白亚基（high molecular weight glutenin subunit,HMW-GS）含量远低于小麦中的。青稞醇溶蛋白和谷蛋白中的二硫键和总巯基含量均低于小麦中的。4 种蛋白的表面疏水性差异不大。青稞谷蛋白的热稳定性高于小麦谷蛋白,不利于其吸收水分和部分展开。红外光谱分析发现小麦醇溶蛋白和青稞醇溶蛋白的二级结构主要由β-转角和β-折叠组成,而小麦醇溶蛋白中的β-转角所占比例更高;青稞谷蛋白和小麦谷蛋白的二级结构主要以β-折叠为主。     

Application of Capillary Electrophoresis to Determine the Technological Properties of Wheat Flours by a Glutenin Index

ABSTRACT:  Capillary electrophoresis was used to characterize glutenin proteins from ancient varieties of Southern Italy common wheat and to determine the technological properties of wheat flours based on a glutenin index. Three zones were identified in the electropherograms, indicated as A, B, and C according to electroelution order. The three zones corresponded to the low molecular weight glutenin subunits and to the y- and x-type high molecular weight subunits, respectively. The ratio B/C was correlated to the alveographic parameter P/L. These results indicated that flours resulting in a B/C ratio lower than 2 produced elastic doughs whereas flours resulting in a B/C ratio higher than 2 produced doughs more resistant to extension. This study showed that capillary electrophoresis is useful for determining the types and quantities of gluten proteins in the evaluation of wheat-flour technological properties of a limited number of noncommercial varieties as evidenced by the x-type content which seems to strongly influence the flour technological parameters.     

不同类型专用小麦HMW-GS和GMP含量与面筋含量的关系

高分子质量谷蛋白质亚基(HMW-GS)是决定小麦加工品质的重要因子,以25个小麦品种为材料,采用SDS-PAGE电泳方法研究亚基组成、各位点(Glu-A1、Glu-B1、Glu-D1)亚基积累量、谷蛋白大聚合体(GMP)含量及其与面筋含量的关系.研究结果表明:低蛋白小麦品种HMW-GS组成主要以"N、7+8/7+9、2+12"亚基组合为主,高蛋白小麦品种HMW-GS组成则主要以"1、7+8/7+9、5+10"亚基组合为主,中等蛋白小麦品种兼有以上两种类型亚基组合;亚基组成相同的小麦,籽粒GMP含量和蛋白质含量仍有较大差异.相关分析表明,HMW-GS亚基总积累量与籽粒蛋白质含量和GMP含量呈极显著正相关,与干、湿面筋含量成正相关;GMP含量与干、湿面筋含量、蛋白质含量均呈极显著正相关,说明小麦品质类型虽与HMW-GS组成有关,但亚基积累强度不同可能是导致籽粒品质类型差异的重要因素之一.     

小米谷蛋白及醇溶蛋白结构特征

采用碱提酸沉法提取小米谷蛋白,乙醇浸提小米醇溶蛋白,对2种蛋白的结构特征进行研究。结果表明,小米醇溶蛋白的组成较为简单,且分子量较小,而小米谷蛋白在高分子量和低分子量都有分布。XRD分析发现二者皆为无定型结构。圆二色光谱测定结果表明,小米醇溶蛋白属于全α型结构,有序性优于小米谷蛋白。另外,通过原子力显微镜观测发现,小米醇溶蛋白呈球状结构,分散状态,而小米谷蛋白分布较为密集。     

干热处理小麦粉对面团品质及流变学特性的影响机制研究

目的 探究干热处理小麦粉对面团品质及流变学特性的影响。方法 将小麦粉分别在80、100、120、140℃温度下干热处理1.0 h,对不同干热处理小麦粉制得面团的湿面筋含量、面筋指数、粉质特性、麦谷蛋白溶胀指数、巯基和二硫键含量、动态流变学特性、微观结构、蛋白间分子作用力进行测定。结果 与未处理组相比,80、100和120℃干热处理湿面筋含量升高2.65%、3.56%和2.21%,140℃干热处理湿面筋含量降低32.07%, 100℃和120℃干热处理,面筋指数升高5.88和1.47, 100℃干热处理1.0 h可以使湿面筋含量和面筋指数达到最大值;面团的形成时间从3.5 min增加至6.0 min,稳定时间从5.0 min增加至7.0 min;面团的拉伸力和麦谷蛋白溶胀指数也呈现出相同的变化趋势。随着干热处理温度的升高,小麦粉中游离巯基含量降低,二硫键含量在100℃处理1.0h时达到最大值9.55μmol/g。此外,小麦粉100℃干热处理提高了面团的黏弹性,面团中的高聚物含量增加;面团中面筋蛋白网络结构形成的更加均匀;面团中蛋白质的共价键和非共价键作用力增强。结论 干热处理小麦粉提升了...     

Variation in concentrations of high-molecular-weight glutenin subunits and macropolymers in wheat grains of a recombinant inbred lines population and in two contrasting eco-sites in China

BACKGROUND: Concentrations of high‐molecular‐weight glutenin subunits and macropolymers in wheat grains are important indicators of grain quality, which are genetically determined and affected by environmental factors. The 6 VS·6AL translocation chromosome segment is reported to own high powdery mildew and yellow rust resistance genes of Pm21 and Yr26. This study investigated the variation in concentrations of high‐molecular‐weight glutenin subunits (HMW‐GS) and glutenin macropolymer (GMP) in response to the 6 VS·6AL translocation segment and the two contrasting sites. RESULTS: Large variations in concentrations of HMW‐GS and GMP were observed within lines containing different HMW‐GS compositions and between the contrasting eco‐sites. However, 6 VS·6AL chromosome translocation segment showed no significant effects on concentrations of HMW‐GS and GMP. In addition, HMW‐GS concentration was also found to be significantly correlated with the GMP concentration. CONCLUSION: Concentrations of HMW‐GS and GMP are largely affected by the eco‐sites and the composition of HMW‐GS, whilst not by the presence of 6 VS·6AL chromosome segment translocation. The 6 VS·6AL translocation is suggested as potential donor for breeding wheat cultivars for high resistence to powdery mildew and yellow rust with less risk of undesirable effects on grain quality. Copyright © 2012 Society of Chemical Industry     

Functional properties of acetylated glutenin and gliadin at varying pH values

Applications of glutenin and gliadin in food products are limited as they cannot provide desirable functional properties. The objectives of this study were to improve the functional properties of glutenin and gliadin by acetylation using acetic anhydride and to study these properties at pH 3, 6 and 9. Under the experimental conditions, about 53.88% of glutenin and 28.46% of gliadin were acetylated. pH of the medium and acetylation of the proteins affected water solubility, water absorption, water holding capacity, emulsifying and foaming properties of the samples. The results of the sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that high and low molecular weight glutenin subunits and ω-gliadins were affected by acetylation, while pH changes had no significant effect on the molecular weight of the proteins. Taken together, the results showed that acetylated glutenin and gliadin can be used as protein sources with good functional properties, particularly at alkaline pH.     

小麦麦谷蛋白与面包品质之间的关系

由于麦谷蛋白在面包制作品质中的重要性，目前有关麦谷蛋白、麦谷蛋白组分、麦谷蛋白多肽和品质之间的关系研究非常活跃。不能被ＳＤＳ或乙酸提取的麦谷蛋白部分与品质指标密切相关，高分子麦谷蛋白亚基与品质相关性并不显著。研究表明某些ＨＭＷ—ＧＳ的存在与不能被ＳＤＳ或乙酸提取的麦谷蛋白含量相关，ＨＭＷ—ＧＳ可能是通过这部分麦谷蛋白含量的变化影响面包制作品质。面团加工过程中面筋提取率有很大变化，这些变化对面团性质和面包品质的重要性有待进一步研究。     

谷蛋白溶涨指数与面制食品质量控制

选用27个中国小麦样品，研究了谷蛋白溶涨指数对于评价中国白盐面条品质评价的适用性。谷蛋白溶涨指数与面带长度呈极显著负相关，与面带厚度呈极显著正相关。谷蛋白溶涨指数各时间(0min，5min，20min)与面条最佳煮面时间、鲜面条最大拉伸阻力、拉伸能量、拉伸长度均呈极显著正相关(除SIGO与最佳煮面时间呈显著正相关)；谷蛋白溶涨指数与可溶性谷蛋白、不溶性谷蛋白含量、面筋指数及蛋白质含量呈极显著正相关；谷蛋白溶涨指数与煮后面条表面韧性呈显著或极显著负相关，与剪切韧性呈显著正相关。谷蛋白溶涨指数可以作为一种品质指标控制面制食品的质量。     

葡萄糖氧化酶对玉米粉品质的影响

本研究以SIG为主要评价指标结合保水力研究了葡萄糖氧化酶对面玉米粉的改良作用。最终确定当葡萄糖氧化酶的浓度为80mg／kg在25℃浸泡6小时后可以使玉米粉的粉质在一定程度上得到改善；同时也证实SIG作为玉米粉加工适性衡量方法具有一定的指导意义。