Molecular Analysis of the Polymeric Glutenins with Gliadin‐Like Characteristics That Were Produced by Acid Dispersion of Wheat Gluten

We had earlier shown that the dispersion of wheat gluten in acetic acid solution conferred gliadin‐like characteristics to the polymeric glutenins. To elucidate the molecular behavior of its polymeric glutenins, the characteristics of gluten powder prepared from dispersions with various types of acid were investigated in this study. Mixograph measurements showed that the acid‐treated gluten powders, regardless of the type of acid, had dough properties markedly weakened in both resistance and elasticity properties, as though gliadin was supplemented. The polymeric glutenins extracted with 70% ethanol increased greatly in all acid‐treated gluten powders. Size exclusion HPLC and SDS‐PAGE indicated that the behavior of polymeric glutenins due to acid treatment was attributed to their subunit composition rich in high molecular weight glutenin subunit (HMW‐GS) and not their molecular size. The gluten prepared with the addition of NaCl in acid dispersion had properties similar to those of the control gluten. The results suggest that ionic repulsion induced by acid dispersion made the polymeric glutenins rich in HMW‐GS disaggregate, and therefore, act like gliadins.     

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。     

不同面筋蛋白组分对小麦淀粉消化特性的影响机理

分别将面筋蛋白、谷蛋白及醇溶蛋白与淀粉按一定质量比（14∶86）混合,运用流变仪、热重分析仪及激光共聚焦显微镜等手段分析不同面筋蛋白组分与淀粉/α-淀粉酶之间的相互作用,以明确面筋蛋白及其不同组分对淀粉消化特性的影响及潜在机理。结果表明：与纯小麦淀粉相比,添加面筋蛋白、谷蛋白及醇溶蛋白使酶解120 min的淀粉消化率分别下降了39.93%、49.48%及26.61%。淀粉与不同面筋蛋白组分之间通过氢键相互作用形成了更稳定的复合物,提高了样品的热稳定性。与面筋蛋白和醇溶蛋白相比,添加谷蛋白在淀粉基质周围形成了更加致密的物理性屏障,更大程度地抑制了酶对淀粉的水解。此外,谷蛋白对α-淀粉酶的抑制率最高（约79%）,激光共聚焦观察到的结果也证实了谷蛋白和α-淀粉酶之间的结合程度更高。研究结果有助于丰富典型蛋白质组分调控食品体系中淀粉消化的机理,为低血糖指数食品的开发提供一定理论指导。     

面筋蛋白及其组分含量对鲜湿面条色泽的影响研究

研究面筋蛋白、麦谷蛋白及麦醇溶蛋白的不同含量对鲜湿面条色泽品质的影响.结果表明:面筋蛋白含量影响鲜湿面条的色泽亮度,麦谷蛋白及麦醇溶蛋白含量影响鲜湿面条的色泽红色度.测色仪参数△L、△a和△b值和面筋蛋白、麦谷蛋白的含量呈线性相关,与麦醇溶蛋白的含量呈非线性相关.     

小麦谷蛋白亚基的组成及含量与谷蛋白聚合体大分子的关系及其对面包烘焙品质的影响

含有高分子量谷蛋白亚基(HMW-GS)5 10的生物型小麦与2 12的生物型小麦相比，前者谷蛋白具有更大的分子量分布。高低分子量谷蛋白亚基的比例对于谷蛋白聚合体分子量的大小起着重要的作用，谷蛋白聚合体的体积越大，含有的高低分子量谷蛋白亚基的比例越高。SDS非可溶性谷蛋白含有较高比例的高低分子量谷蛋白亚基，并且其分子量要比可溶性谷蛋白聚合体的大。谷蛋白聚合体分子量分布的差异是不同小麦品种面包烘焙品质存在差异的重要因素。     

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.     

柠檬酸处理对小麦面筋蛋白酶解特性的影响

以复合蛋白酶为水解酶,试验研究了小麦面筋蛋白酶解前柠檬酸预处理对其酶解特性的影响.通过单因素试验和正交试验确定柠檬酸预处理的最佳工艺条件为:柠檬酸浓度为0.1%(m/V),温度为50℃,处理时间为30min.同时研究了柠檬酸处理后小麦面筋蛋白在酶解过程中的水解度和蛋白提取率的变化规律.     

基质固相分散-高效液相色谱法测定蔬菜中邻苯二甲酸酯类

研究了蔬菜中的邻苯二甲酸二丁酯(di-n-butyl phthalate,DBP)和邻苯二甲酸二辛酯(di-2-ethylhexyl phthalate,DEHP)基质固相分散处理和高效液相色谱测定方法。蔬菜样品经弗罗里硅土和石墨化碳黑研磨均匀后,用乙酸乙酯淋洗净化。结果表明:DBP和DEHP在0.1～10mg/L范围内具有良好的线性,样品的添加回收率在86.2%～91.4%,相对标准偏差2.9%～4.8%。该方法操作简便经济,分析速度快,可适用于大批量样品分析。     

Laboratory‐scale Dry/Wet‐Milling Process for the Extraction of Starch and Gluten from Wheat

A laboratory‐scale process is presented for the manufacture of starch and gluten from wheat. Main feature of this process is that whole wheat kernels are crushed dry between smooth rolls prior to wet disintegration in excess water in such way that gluten formation is prevented and fibres can be removed by sieving. Centrifugation of the endosperm suspension yields a dough which can be separated into starch and gluten using an established batter process. The results suggest that starch recovery is increased in comparison to a conventional wheat flour process without a concomitant decrease in protein recovery. Although starch purification was omitted, a total starch with a low protein content is obtained. On the other hand, the protein content of the gluten fraction is rather low due to difficulties in removing the starch. Despite this, the effect on dough mechanical properties by the addition of gluten obtained from wet‐milled wheat is comparable to the effect of gluten from flour.     

Utilization of Barley or Wheat Bran to Bioconvert Glutamate to γ‐Aminobutyric Acid (GABA)

This study deals with the utilization of agro‐industrial wastes created by barley and wheat bran in the production of a value‐added product, γ‐aminobutyric acid (GABA). The simple and eco‐friendly reaction requires no pretreatment or microbial fermentation steps but uses barley or wheat bran as an enzyme source, glutamate as a substrate, and pyridoxal 5’‐phosphate (PLP) as a cofactor. The optimal reaction conditions were determined on the basis of the temperatures and times used for the decarboxylation reactions and the initial concentrations of barley or wheat bran, glutamate, and PLP. The optimal reactions produced 9.2 mM of GABA from 10 mM glutamate, yielding a 92% GABA conversion rate, when barley bran was used and 6.0 mM of GABA from 10 mM glutamate, yielding a 60% GABA conversion rate, when wheat bran was used. The results imply that barley bran is more efficient than wheat bran in the production of GABA.     

Protein Characteristics that Affect the Quality of Vital Wheat Gluten to be Used in Baking: A Review

The use of vital wheat gluten in the baking industry and wheat flour mills aims to improve the rheological characteristics of flour considered unsuitable to obtain products such as sliced bread, French bread, high‐fiber breads, and other products that require strong flours. To improve characteristics such as flour strength, dough mixing tolerance, and bread volume, vital wheat gluten is added to flour at levels that can vary from 2% to 10% (flour basis), with 5% being a commonly used dosage. However, the vital wheat gluten commercialized in the market has few quality specifications, especially related to the characteristics of the proteins that constitute it and are responsible for the formation of the viscoelastic gluten network. Information on protein quality is important, because variations are observed in the technological quality of vital wheat gluten obtained from different sources, which could be associated to damage caused to proteins during the obtainment process. Several tests, either physical–chemical analyses, or rheological tests, are carried out to establish gluten quality; however, they are sometimes time‐consuming and costly. Although these tests give good answers to specify gluten quality, flour mills, and the baking industries require fast and simple tests to evaluate the uses and/or dosage of vital gluten addition to wheat flour. This review covers the concepts, uses, obtainment processes, and quality analysis of vital wheat gluten, as well as simple tests to help identify details about protein quality of commercial vital wheat gluten.     

Characteristics of yeast flora in Chinese strong‐flavoured liquor fermentation in the Yibin region of China

The yeast community in the Chinese strong‐flavoured liquor region of Yibin was investigated and the ethanol producing abilities and extracellular enzymes activities of the isolates were tested. A total of 110 yeast were isolated on Wallerstein Laboratory medium and through 26S rRNA D1/D2 region sequence analysis identified as 13 yeast species. These were Wickerhamomyces anomalus, Debaryomyces hansenii, Issatchenkia orientalis, Lodderomyces elongisporus, Clavispora lusitaniae, Saccharomyces cerevisiae, Pichia fermentans, Pichia manshurica, Pichia membranifaciens, Torulaspora delbrueckii, Trichosporon insectorum, Trichosporonoides megachiliensis, Zygosaccharomyces bailii, and one uncertain species. These yeast species, composed of various strains, formed the special yeast community in the Yibin region. Approximately 73.6% of the strains belong to the four dominant species: W. anomalus, D. hansenii, I. orientalis and L. elongisporus. The 110 yeast strains produced 0.6–9.0% (v/v) alcohol (average of 5.4%, v/v) in a grain medium, and 0.2–7.2% (v/v) alcohol (average value of 2.9%, v/v) in a yeast extract–peptone–dextrose medium. Furthermore, the 49 strains that produced pectinase, lipase, cellulase, amylase or protease generally showed better ethanol‐producing ability than those strains that do not produce extracellular enzymes. This work profiles the ethanol‐producing ability and the organic matter utilization of the yeast community in Chinese strong‐flavoured liquor produced in the Yibin region and provides a better understanding of Chinese strong‐flavoured liquor fermentation. Copyright © 2016 The Institute of Brewing & Distilling     

Performance of indigenous yeasts in the processing of Chinese strong‐flavoured liquor during spontaneous mixed solid‐state or submerged fermentation

To explore the in situ metabolic characteristics of yeasts involved in the spontaneous fermentation process of Chinese strong‐flavoured liquor, a comparison was conducted between solid‐state fermentation (SSF) and submerged fermentation (SmF) when supplemented with 24 indigenous yeast strains, with a focus on the production of ethanol and a broad range of volatile compounds responsible for the characteristics of Chinese strong‐flavoured liquor. Under the various experimental conditions, the 24 indigenous yeast strains showed different influences on the mixed fermentation system. The fluctuations caused by different yeast strains in the mixed system were less than those caused by the different fermentation modes relative to the formation of flavour compounds. SSF was found to be more suitable for the production of ethanol, methanol and ethyl lactate, whereas SmF was more suitable for the production of 10 higher alcohols, four esters and four acids. This study revealed the relationships amongst the indigenous yeasts, SSF, and the distinctive flavour profiles of Chinese strong‐flavoured liquor. This work provides evidence of the existence of internal stability in spontaneous SSF, thereby facilitating a better understanding of the fermentative mechanism in the SSF process for Chinese strong‐flavoured liquor production Copyright © 2015 The Institute of Brewing & Distilling     

Utilization of Transglutaminase to Increase the Level of Barley and Soy Flour Incorporation in Wheat Flour Breads

ABSTRACT: This study investigated the possibility of incorporating barley or soy flour into wheat flour using transglutaminase (TG)-catalyzed cross-linking, without deterioration in bread quality. A Farinograph and texture analyzer were used to examine mixing properties and extensibility of doughs, respectively. Addition of increasing levels of barley/soy flour (with and without TG) increased Farinograph water absorption in the soft and hard wheat cultivars studied. Dough resistance increased and extensibility decreased with TG treatment. TG showed great promise in processing of bread supplemented with barley flour, even at a very low level (0.25%, wt/ wt), but did not notably improve the quality of soy flour-supplemented breads.     

Functional Properties and Retrogradation of Heat‐Moisture Treated Wheat and Potato Starches in the Presence of Hydroxypropyl β‐cyclodextrin

Some functional and retrogradation properties of native and heat‐moisture treated potato and wheat starches were examined in the presence of hydroxypropyl β‐cyclodextrin (HPβ‐CD). HPβ‐CD increased swelling factor, amylose leaching, and solubility of both native and heat‐moisture treated wheat starches but it had less impact on corresponding potato starches. Gelatinization enthalpy of native wheat starch was decreased in the presence of HPβ‐CD but was increased in potato starch with increasing concentration. Reduction of amylose‐lipid complex endotherm in both native and heat‐moisture treated wheat starch was observed in the presence of HPβ‐CD. Heat‐moisture treatment did not change the transition parameters of amylose‐lipid complex showing its resistance to hydrothermal treatment. HPβ‐CD greatly decreased the pasting temperature of wheat starch. Cold paste viscosity of both native and heat‐moisture treated wheat starch was increased by HPβ‐CD to a greater extent than corresponding potato starch. Amylopectin retrogradation of all the starches was unaffected in the presence of HPβ‐CD but heat‐moisture treatment slightly decreased retrogradation of potato starch. These results suggest that HPβ‐CD can disrupt the amylose‐lipid complex within the starch granule in both native and heat‐moisture treated wheat starch but has no influence on amylopectin retrogradation. However, greatly increased wheat starch setback with HPβ‐CD indicates its greater effect on wheat starch amylose retrogradation.     

Performance of quinoa (Chenopodium quinoa Willd) flour in the manufacture of gluten‐free spaghetti

The objective of this work was to assess the performance of mixtures of corn and quinoa (Chenopodium quinoa Willd) flours in the development of a spaghetti‐type product. Cooking quality (loss of solids, volume increase, weight increase), texture (adhesiveness, elasticity), peak and final viscosities and moisture content of the pre‐gelatinised flour mixtures were the physical parameters studied. The mean values for loss of solids, weight increase, volume increase, adhesiveness and moisture were 162 g kg⁻¹, 2.3 times, 2.6 times, 2090.7 g and 384 g kg⁻¹ respectively. Peak viscosity and elasticity provided information relevant, yet not definitive, to both formulation and processing of the product. However, the model developed was predictive for final viscosity. The combination of independent variables that resulted in higher elasticity values, desirable for spaghetti, were short thermal treatment and low‐to‐medium quinoa additions. All peak viscosities were low with respect to the untreated flour. For final viscosity, however, the best combinations were short heat treatments across the entire range of quinoa contents. Sensory acceptability testing of the spaghetti by a consumer panel was also included. © 2000 Society of Chemical Industry     

Characterization of the Bread Made with Durum Wheat Semolina Rendered Gluten Free by Sourdough Biotechnology in Comparison with Commercial Gluten‐Free Products

Durum wheat semolina was fermented with sourdough lactic acid bacteria and fungal proteases aiming at a complete gluten hydrolysis. The gluten‐free (GF) semolina, added with naturally GF ingredients and structuring agents, was used to produce bread (rendered GF bread; rGFB) at industrial level. An integrated approach including the characterization of the main chemical, nutritional, structural, and sensory features was used to compare rGFB to a gluten‐containing bread and to 5 commercial naturally GF breads. High‐performance liquid chromatography was used for free amino acids (FAAs), organic acids, and ethanol analysis. A methanolic extract was used for determining total phenols and antioxidant activity. The bread characterization also included the analysis of dietary fibers, mycotoxins, vitamins, and heavy metals. Beyond chemical analysis, nutritional profile was evaluated considering the in vitro protein digestibility and the predicted glycemic index, while the instrumental texture profile analysis was performed to investigate the structure and the physical/mechanical properties of the baked goods. Beyond the huge potential of market expansion, the main advantages of durum wheat semolina rendered GF can be resumed in the high availability of FAAs, the high protein digestibility, the low starch hydrolysis index, and the better technological properties of bread compared to the commercial GF products currently present on the market. Vitamins, minerals, and dietary fiber profiles are comparable to those of gluten‐containing wheat bread. Also the sensory profile, determined by a panel test, can be considered the most similar to those of conventional baked goods, showing all the sourdough bread classic attributes.