谷氨酰胺转胺酶对面粉品质的改良作用

应用单一酶制剂谷氨酰胺转胺酶对面粉进行了品质改良研究,结果表明,谷氨酰胺转胺酶可以催化面筋蛋白形成ε (γ 谷氨酰基)赖氨酸共价键,从而明显改善面团的粉质特性,使面团的形成时间、稳定时间、断裂时间增加,面团的弱化度降低.在拉伸曲线中可以看出加酶的面团抗延伸阻力增加,面团的延伸性下降,粉力增加到2～3倍后逐渐稳定.应用AR 1000流变仪根据时间扫描动态测量模式考察了面团的贮能模量随酶反应时间的变化情况,与对照相比,添加质量分数为0.25%和0.5%的谷氨酰胺转氨酶可使面团的贮能模量显著增加,0.5%的加酶量使贮能模量增加更快.此外,加酶面团的持水性增大,面团的表面黏性下降.     

谷氨酰胺转胺酶对面粉品质的改良

小麦是我国的主要粮食作物,产量和种植面积均居世界各国之首,但其品质受地理环境、气候、种植方式等因素的影响,难以生产优质的面粉[1].     

谷氨酰胺转胺酶对面粉品质的改良作用

谷氨酰胺转胺酶可以催化面筋蛋白形成ε-(γ-谷氨酰基)赖氨酸共价键，从而明显改善面团的粉质特性。使面团的形成时间、稳定时间增加，面团的弱化度降低；同时加酶的面团抗延伸性阻力增加，面团的延伸性下降。此外，加酶面团的持水性增大，面团的表面粘性下降。     

谷氨酰胺转胺酶对大豆面包品质及加工特性的影响

研究在含12.5%大豆粉的面粉中添加不同水平的谷氨酰胺转胺酶(TG)(0.25%、0.50%、0.75%和1.00%)对形成面团的粉质特性、拉伸特性、超微结构以及面包烘焙品质的影响.结果表明:混合粉中添加不同水平的TG后与未加TG的混合粉相比,面团的吸水率增加,面团的形成时间和稳定时间增加,面团的弱化度有所下降.添加不同水平的TG后,面团的抗拉伸阻力Rax增加,延伸性下降.在0.50%～0.75%范围内添加TG可改善富含大豆粉面团的超微结构和面包的烘焙品质.     

谷氨酰胺转胺酶的功能特性及其在面粉制品加工中的应用

谷氨酰胺转胺酶是一种催化酰基转移反应的转移酶，它可使蛋白分子间和分子内产生共价交联反应，是一种良好的面筋改良剂。主要论述了谷氨酰胺转胺酶的功能特性、作用机理、改良面筋的流变学特性以及它在面粉制品加工中的应用。     

谷氨酰胺转胺酶对面粉糊化性质和面条品质的影响

研究2种谷氨酰胺转胺酶(TG-M和TG-B)对面粉糊化性质和面条品质的影响。结果表明,这2种谷氨酰胺转胺酶对面粉的糊化温度影响不显著;随TG-M添加量的增加,面粉的峰值黏度、谷值黏度、最终黏度、回生值和崩解值变化不显著;随TG-B添加量的增加,面粉的峰值黏度、谷值黏度、最终黏度、回生值和崩解值呈递增的趋势;添加谷氨酰胺转胺酶能改善面条的质构特性,TG-M与TG-B对面条质构特性的影响没有明显差异;TG-M和TG-B在面条中的添加量不应超过0.5%。     

小麦内源蛋白水解酶对面团流变学特性的影响

通过小麦内源蛋白水解酶对小麦粉面团流变特性影响的研究,结果表明小麦蛋白水解酶对面团流变强度上有显著的弱化作用,但对不同品种小麦粉的作用程度差异较大。在用乳酸调成的ＰＨ４环境下,小麦蛋白水解酶对面团的软化作用非常迅速。小麦内源蛋白水解酶易热失活,抑胃肽、ＮａＣｌ均能通过抑制小麦蛋白水解酶活力,有效抑制面团的软化作用。     

谷氨酰胺转胺酶对搅拌型酸奶品质的影响

因为谷氨酰胺转胺酶对乳蛋白有交联作用,所以在酸奶制作中加入谷氨酰胺转胺酶可以提高酸奶的品质,将0.2g/L牛乳的谷氨酰胺转胺酶使用不同的添加方法(对酶灭活和不灭活)应用到酸奶制作中,通过酸奶硬度、持水力、流变特性、乳酸菌等指标的变化及综合感官评价,评定谷氨酰胺转胺酶的最适添加方法。结果表明两种不同的酶添加方法都可以减弱酸奶后酸化,提高酸奶硬度、持水力和剪切应力。TGase酶与发酵剂同时加入显著提高了酸奶的理化特性(p<0.05),硬度在第21d达到最大,与对照组相比提高8.48g,持水力随贮存时间的延长,不断增大,增幅为5.41%。在贮存后期TGase酶活力减弱,对酸奶的质构无不良影响,而且这种方法不需要额外的酶反应时间,热处理工序及设备,符合实际生产的需求。      

一些蛋白质和多肽对谷氨酰胺转胺酶热稳定性的影响

谷氨酰胺转胺酶（TGase）是一种催化蛋白质分子间产生共价交联的硫醇酶类,但其热稳定性较差,通过35～60℃之间的热处理研究,发现谷朊粉、大豆多肽、乳清蛋白、酪蛋白酸钠、乳清粉和脱脂乳6种蛋白和多肽物质对TGase酶活都表现出保护作用,其中酪蛋白酸钠和乳清蛋白较为显著。采用TG/DSC分析,我们获得了上述六种蛋白物质对TGase的相变温度（Tm）,相变热焓（ΔH）和失重率（LW）影响的数据,其中酪蛋白酸钠对TGase的三种热力学参数改变最大,分别为32℃,40.5J/g和-7.0%。加入0.1%～2.0%的上述6种蛋白和多肽物质对TGase的冻干过程也具有保护作用,以0.5%的谷朊粉添加效果较好。      

源于不同菌种的谷氨酰胺转胺酶的特性研究

本文对TG-K和TG-N的特性进行对比研究发现:TG-K和TG-N粗酶酶活分别为11.32、9.41U/ml;对酶进行分离纯化的步骤越多,酶活力和蛋白含量就损失的越多,但是TG-K降低的幅度比TG-N小;经SDS-PAGE凝胶电泳可知TG-K的分子量为41.5kDa,而TG-N的分子量为39.6kDa,不同离子对TG-K和TG-N交联酪蛋白的影响不尽相同;经扫描电镜对酸奶凝块的超微结构进行观察,证实TG-K比TG-N更适合催化交联酪蛋白。     

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     

香菇粉对小麦面团热机械学和动态流变学特性的影响研究

本试验通过测定不同比例的香菇粉和小麦粉混合粉的热机械学和动态流变学特性,研究香菇粉对小麦面团特性的影响。结果表明,香菇粉的添加使小麦面团的吸水率增大,面团的形成时间和稳定时间先下降后上升,相应的蛋白质弱化度先升高后降低。香菇粉的添加使小麦面团的峰值黏度和回生值均显著降低。动态流变学试验显示:香菇粉的添加使得小麦面团的黏弹特性发生了显著的变化,储能模量(G')与损失模量(G")均呈现先降低后升高的趋势。而tanδ随香菇粉比例的增大呈现了先略微升高后明显降低的趋势,表明了混合体系中分子交联的程度有所增加,弹性比例增大。     

配麦和配粉对小麦粉面团流变学特性的影响

选用7种高、中、低筋小麦,对其品质进行综合分析;根据分析结果以水饺粉为目标粉进行配麦和配粉实验,对混合粉的流变学特性进行分析研究。结果表明差异性大的小麦(粉)以合适的比例搭配能明显改善混配粉的流变学特性。配麦和配粉在提高稳定时间,降低弱化度,改善拉伸特性方面区别并不明显,但在降低吸水率和拉伸度方面配粉比配麦表现效果更加明显。     

米粉对面团流变特性及酥性饼干品质的影响

目的 探究了米粉的添加对面团流变学特性以及酥性饼干品质的影响。方法 选取了3种米粉(粳糯米粉、籼糯米粉、普通粳米粉)分别以0%、10%、20%、30%的比例替代中筋小麦粉，研究分析了米粉-中筋小麦粉混合粉的糊化特性，面团的粉质拉伸特性，动态流变以及酥性饼干的理化性质，质构特性及感官品质。结果 随着两种糯米粉添加量增加，混合粉的糊化特征值均呈下降趋势，而添加普通粳米粉后则趋势相反；添加米粉后混合面团的吸水率和弱化度随着三种米粉的添加量的增加显著升高，分别可达65.7%和160.50，而面团形成时间和稳定时间则显著降低(P<0.05)；混合面团的弹性模量（G''），黏性模量（G"）和损耗角正切值（tanδ）随着米粉添加量的增加而逐渐减小，表明米粉的添加减弱了面筋网络的形成；与低筋粉酥性饼干相比，混合粉酥性饼干的延展比较低，且三种米粉的添加可显著提升酥性饼干的脆性，经感官评价及综合比较后得出添加20% 籼糯米粉的混合粉饼干整体品质较佳。结论 通过在中筋面粉中加入米粉后可以有效改变面团的特性，以替代低筋面粉应用于酥性饼干的加工 ，本研究也为米粉在酥性饼干专用粉的制备奠定了理论基础。     

Effects of japonica rice flour on the mesoscopic and microscopic properties of wheat dough protein

The aim of this study was to study the effects of twelve varieties of japonica rice flour on the gluten protein composition and structure of wheat dough. Experimental results indicated that the addition of japonica rice flour significantly decreased the α-helix structure in the gluten protein sample, but increased the random coil content, indicating that the protein secondary structure became more disordered. The ratio of α-helix/β-sheet structures in the dough supplemented with different varieties of japonica rice flour was decreased, contributing to improved dough stability. Increasing the proportion of japonica rice flour from 10% to 40% significantly decreased the sulfhydryl content of the mixed flour dough. However, the total sulfhydryl content was only positively correlated with the amount of Longdao 19 japonica rice flour, reaching a maximum of 25.34 mol g⁻¹ at 40% japonica rice flour. The gluten structure of mixed flour dough typically forms a porous three-dimensional network, with the Longdao 19, 20, 23 and 25, Longjing 31 and Mudanjiang 31 japonica rice flours leading to improved gluten protein networks. In summary, the supplementation of standard wheat flour with japonica rice flour can alter dough properties and gluten structure.     

Sheeting of wheat flour dough

A combined experimental, analytical and numerical study of sheeting of wheat flour dough was performed. The material behaviour was defined using a non‐linear viscoelastic model calibrated with data obtained from uniaxial compression, loading–unloading and stress relaxation tests. Tests were performed using an instrumented small‐scale rolling rig. The roll speed and roll gap were varied to determine the effect on the steady‐state vertical force and exit thickness. Experiments were performed using one‐stand as well as a two‐stand roll set up. The analytical model which assumed perfect plasticity led to significantly lower forces than the experimental data. The numerical predictions were accurate at small reduction ratios. The exit thickness of the dough sheet was predicted accurately from the numerical model. For the two‐stand rolling, the numerical data were not accurate when a significant level of stress developed in the dough between the two roll stands.     

Effects of microencapsulated glucose oxidase on wheat flour dough properties and Chinese steamed bread quality

This study was to investigate the effects of microencapsulated glucose oxidase (MGO), in comparison with free glucose oxidase (GO), on wheat flour dough properties and Chinese steamed bread (CSB) quality. Effects on wet gluten (WG) content, farinograms and extensograms properties, dynamic rheological properties, microscopic structure, texture profile and sensory evaluation scores were studied. The results demonstrated that MGO catalysed the oxidation of dough at a much slower speed and exerted relatively great advantages in many aspects such as WG content, extensibility, G′ (Elastic modulus), G″ (viscous modulus), tan δ (equal to G′/G″), microstructure and texture properties and sensory evaluation scores of CSB, compared with free GO. The results suggested that slow oxidation of MGO was superior to free GO based on the improvements of wheat flour dough properties and subsequent CSB quality.     

小麦面粉蛋白质特性和面团流变学特性的关系

目的探究小麦面粉蛋白质理化特性与面团流变学特性之间的关系。方法以19份抗旱节水鉴定品种小麦籽粒为试验材料,测定了蛋白质、湿面筋、谷蛋白大聚体含量、沉降指数等面粉蛋白质理化特性,以及粉质参数和拉伸参数等面团流变学特性,采用通径分析研究了面粉蛋白质理化特性与面团流变学特性的关系。结果面粉蛋白质含量对面团吸水率直接增强效应较大,但对稳定时间、拉伸长度的抑制效应较大;谷蛋白大聚体含量对形成时间、最大拉伸阻力、拉伸面积的直接增强效应和综合增强效应均较大;沉降指数对稳定时间和最大拉伸阻力、拉伸面积的直接增强和综合增强效应较大;所测蛋白质理化特性中未发现对拉伸长度有增强效应的指标。结论面粉中谷蛋白大聚体含量和沉降指数是对面团形成时间、稳定时间、拉伸阻力影响较大的因素,影响为正效应,可为专用面粉生产质量控制提供参考。     

Effects of plasma-activated water and heat moisture treatment on the properties of wheat flour and dough

Plasma-activated water (PAW) production and use is an emerging technology for enhancing product safety, extending shelf-life and quality retention, and promoting sustainable processing. At present, it has generated considerable attention for applications to starch and flour modification. This work presents an innovative approach to wheat flour (WF) modification using PAW and heat-moisture treatment (HMT), and compares this approach with distilled water (DW) treatment. As expected, PAW and HMT promoted flour granule clustering, increasing particle size. These treatments accelerated molecular interactions between wheat starch and non-starch components (e.g. proteins and lipids), which eventually increased resistant starch (RS) content. Addition of modified flour (30 g) to WF positively affected its rheological properties, and closely bound water content of the dough. The gluten protein network structure in the dough suffered varying degrees of damage. In conclusion, our results showed that PAW and HMT may provide a novel beneficial method for modifying wheat flour during food processing to obtain viscoelastic wheat flour products with nutritional functions.