转谷氨酰胺酶对大豆分离蛋白交联聚合作用研究

该文研究利用微生物来源的转谷氨酰胺酶(MTGase)对大豆分离蛋白进行交联聚合,研究不同反应条件对聚合反应影响,并对聚合后蛋白凝胶性进行研究。结果显示,大豆分离蛋白是MTGase良好底物;得到较好聚合反应条件为:温度45℃或50℃;pH7.0;反应时间2 h时最适加酶量为5U/g。聚合后蛋白凝胶特性,尤其是凝胶硬度和粘性有较显著提高。     

Effects of Microbial Transglutaminase on the Wheat Proteins of Bread and Croissant Dough

ABSTRACT: Transglutaminase is a crosslinking enzyme that is finding increasing use in foods, yet the molecular changes responsible for its effects are not fully understood. Proteins were extracted from bread and croissant doughs that had been treated with transglutaminase and compared to those from control doughs by size exclusion high performance liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis. Transglutaminase increased the amount of protein extracted in the gliadin fraction in both bread and croissant doughs. In croissant doughs, a corresponding decrease in the protein extracted in the albumin to globulin fraction was seen. In each case, crosslinking of the high molecular weight glutenins was observed. The possible role of each of these changes on the functional properties of baked products is discussed.     

Effect of transglutaminase on the functional properties of GDL (glucono‐delta‐lactone) cold‐set soybean glycinin gel

Cold‐set soybean glycinin gel was prepared by cross‐linking of soybean glycinin (non‐preheated and preheated) at pH 8.0 and 50 °C using transglutaminase (TG), followed by cold‐set acidification using glucono‐δ‐lactone (GDL). Dynamic oscillatory rheological measurements (both under non‐preheat and preheat conditions) showed that there was a substantial increase in the elastic (G′) and viscous (G″) moduli of enzyme treated gels. The moduli also showed similar frequency dependence. The yield strains of enzyme treated gels were clearly higher than that of the gels without enzyme treatment. Texture profile analysis indicated that preheat and enzyme treatments have beneficial effect on hardness, fracturability and gumminess of gels. Thermal and enzyme treatments have synergetic effect to improve the strength of gels, which is also consistent with the results of rheological measurements. These results demonstrated that heat treatment followed by TG treatment and GDL acidification improved the functional properties of soybean glycinin cold‐set gel.     

Influence of different pretreatments on the accessibility of transglutaminase and tyrosinase to wool fibre proteins

Wool fibres are subject to a variety of industrial chemical treatments prior to finishing processes. The influence of such treatments on subsequent enzymatic treatments is still poorly characterised, but its importance is paramount to achieve maximal efficiency of enzymatic action on the fibres. The effect of such treatments on wool fibre structure and their significance on the accessibility of the enzymes transglutaminase and tyrosinase to their target amino acids within wool proteins was investigated. These enzymes are of great interest due to their potential as protein cross‐linkers and their capability to covalently graft beneficial compounds onto proteins. The accessibility of target amino acids was assessed using specific peptides tagged with fluorescent probes, followed by epifluorescence or confocal microscopy. Differences in the action of the different chemical pretreatments were found, with a treatment with permonosulphuric acid resulting in the greatest level accessibility to both enzymes, followed by chlorination and plasma treatments. This was confirmed by the increase in tensile strength of treated wool observed in the enzyme‐treated yarns. This work illustrates that the accessibility of these enzymes to their target aminoacids in solid substrates such as wool is key for their action and to achieve the desired property modifications. The techniques used have the advantage of permitting the visual monitoring of the diffusion of the active enzymes through the wool fibre structure and to relate this to the extent of enzymatic reaction. Crucially, this will allow an informed choice of the best wool processing stage at which to introduce such enzyme treatments.     

Physical Properties of Soy Bean and Broad Bean 11S Globulin Gels Formed by Transglutaminase Reaction

Physical properties of transglutaminase-induced glycinin and legumin gels were compared with thermally induced gels. Results of deformation tests showed that transglutaminase-induced gels were more rigid and elastic than thermally induced gels. From creep compliance tests, all elastic moduli and viscosities except Newtonian viscosity were higher for transglutaminase-induced gels. Electron micrographs revealed that network structures of transglutaminase-induced gels were composed of larger unit particles forming more developed strands and clusters. More rigid and elastic gels were formed from glycinin as compared to legumin by both gelling methods.     

转谷氨酰胺酶用于羊毛改性中的修复作用

文章研究了转谷氨酰胺酶(TG酶)浓度、处理时间、pH值和温度4因素对TG酶修复羊毛性能的影响.确定TG酶的最佳工艺条件为:浓度4%(owf),处理时间2h,pH值6.5～7.0,处理温度37～40℃.经蛋白酶与TG酶处理过的纱线,与只经蛋白酶处理的纱线相比,强力能明显提高.文章还分析了TG酶对羊毛的修复机理.     

应用二次回归正交旋转组合设计优化转谷氨酰胺酶作用的乳清蛋白交联条件

考察了pH、催化时间、催化温度及加酶量对转谷氨酰胺酶作用WPI形成交联产物的粘度影响,并对影响因素进行优化,找出最佳组合。该研究共分两个实验进行,实验1考察pH、时间、温度及加酶量单个因素对转谷氨酰胺酶交联作用的影响;实验2是基于单因素实验结果,采用四因素(pH、催化时间、催化温度、加酶量)五水平回归正交旋转设计,对WPI经转谷氨酰胺酶交联后产生最大粘度的最佳条件进行优化,以便确定实验多元回归方程和获得较大WPI黏度的最佳条件。实验结果表明:交联时间4h、交联温度50℃、pH8.0和加酶量20u/g时,具有最佳粘度值,转谷氨酰胺酶作用效果最佳。     

Evaluation of some physico-chemical properties of restructured trout and hake mince during cold gelation and chilled storage

Cold gelation was carried out on trout (Oncorhynchus mykiss) or on hake (Merluccius merluccius) mince with or without addition of fish oil and using microbial transglutaminase (MTGase). Products were stored at 4 °C for 6 days and lipid oxidation, protein oxidation, texture, water binding capacity, and colour were followed. Results indicated that MTGase was able to generate gels with good properties for both trout and hake. Gels prepared with trout were oxidised whilst gels prepared with hake were stable toward oxidation even in the presence of 5% fish oil. However, in the presence of oil, as an alternative for generating omega-3 enriched products, the activity of MTGase was impaired, as the gels took longer to reach maximum hardness. Furthermore, in all samples containing MTGase, protein oxidation was high.     

Effects of phenolic acids and transglutaminase on soft wheat flour dough and baked products

BACKGROUND: The effects of phenolic acids on the physical properties of soft wheat flour dough and baked soft wheat flour products were investigated. Transglutaminase (TG) was added to observe the effects of non‐disulfide crosslinks on phenolic acid treated dough. Ferulic acid, p‐coumaric acid or fumaric acid was blended with pastry flour at a level of 250, 500 or 1000 ppm of flour dry weight, respectively. RESULTS: The addition of phenolic acids, TG or a mixture of phenolic acids and TG to flour had no effect on the mixing properties of the doughs but significantly affected 90 min rested dough. The addition of phenolic acids decreased the maximum resistance and increased the extensibility of 90 min rested dough, and TG reversed the effects of phenolic acids on the rested dough. The physical characteristics of cookies blended with each phenolic acid plus TG were not significantly different (P > 0.01) from those of the control cookies. However, TG with and without phenolic acids had significant effects on the moisture content, weight and volume of crackers. CONCLUSION: These results suggest that the addition of phenolic acids and TG in the absence of a fermentation process do not affect the physical properties of soft wheat flour products. The fermentation process allows the chemical reaction of the phenolic acids and TG to occur before the soft wheat flour products are baked. Copyright © 2008 Society of Chemical Industry