戊二醛与蛋白质反应的特点

戊二醛与蛋白质反应的特点的是活性高、反应快、给合量高、交联性能好，且交联产物性质稳定并可保持蛋白质的精细结构，对酶的活性影响小，固定的蛋白质染色性能好。     

蛋白质纤维的交联

可再生蛋白质纤维的耐水性和强力差,是阻碍其应用的主要弊端,而交联是提高蛋白质纤维机械性能和耐水解性最有效的方法,同时能提高羊毛、蚕丝等天然蛋白纤维的服用性能。介绍了各种交联剂交联蛋白质纤维的方法,特别是多元羧酸在蛋白质纤维交联中的应用。在低温和不含磷的催化剂的条件下对再生蛋白进行交联,能够得到具有较高强力和耐水性的再生蛋白质纤维,满足纺织、医疗等领域的应用。     

食品中的蛋白质交联技术

综述了食品中的美拉德反应衍生的交联、二硫键交联反应、转谷氨酰胺酶交联反应、酪氨酸残基引发的交联反应、脱氢蛋白质交联等五种蛋白质交联技术以及研究进展,通过蛋白质交联可以提高蛋白质的功能性质和营养价值,从而扩大了蛋白质的应用范围。     

芳伯胺染料/甲醛复合修饰蚕丝的结构性能研究

基于三组分Mannich反应蛋白质修饰的基本原理,采用自制的芳伯胺染料作为修饰显色剂的手段,文章研究了芳伯胺染料/甲醛复合对蚕丝素蛋白发生共价键合修饰的同时,甲醛与蚕丝素蛋白氨基酸残基反应形成交联产物及其对蚕丝结构及性能的影响,为实现蛋白质材料功能化的修饰提供一定的理论依据。采用以氨基酸模拟蚕丝氨基酸残基与甲醛的反应,通过质谱和红外光谱等分析手段,表征了甲醛与蚕丝素蛋白中氨基酸残基之间的交联作用。通过测定蚕丝的断裂强力、断裂伸长、折皱回复角等物理指标,进一步揭示了甲醛与蛋白质氨基酸残基发生交联对蚕丝织物性能的影响。     

蛋白质交联研究概况

通过蛋白质交联可对蛋白质进行改性,该文简述蛋白质两种交联:化学交联和酶交联。目前 蛋白质化学交联剂主要是戊二醛,酶交联剂主要是转谷氨酰胺酶;通过蛋白质交联可改变食品组织结构 和功能性质,因此蛋白质交联在食品中有较广阔应用前景。     

多糖-蛋白质酶促共聚物研究进展

蛋白质和多糖作为食品主要组成中的生物活性大分子,在食品体系中起重要作用。近年来,研究人员试图通过蛋白质与多糖结合进而改善其功能特性。酶促交联方式作用条件温和,反应速率较快,反应产物无毒害作用,并能赋予多糖和蛋白质新功能。因此,主要介绍三大酶促反应体系(过氧化物酶、微生物转谷氨酰胺酶、漆酶)作用原理及多糖与蛋白质酶促交联产物表征技术,为多糖-蛋白质酶促交联产物在食品体系中的应用提供思路。     

吡喃法合成戊二醛

前言戊二醛是一种优良的双官能团交联剂。它与蛋白质发生交联反应的特点是交联性能好,结合量高,产物稳定,而且能较好地保持蛋白质的构型。六十年代以来,其应用范围不断扩大。在制革行业中,戊二醛是一种很好的多性能鞣剂,能赋予革优异的耐汗、耐热、皂洗等性能,受到国内外制革工作者的重视。在医药卫生部门,戊二醛作为一种灭菌谱广、高效低毒,刺激腐蚀性小的新型杀菌剂得到了普遍的应用。在使用电子显微镜进行生物学、医学研究时,由于戊二醛能较     

交联作用对蛋白类食品的影响

关于蛋白质交联作用对食品感官品质影响的研究已经得到了足够的重视,但是关于不同原因所导致的蛋白质交联作用对蛋白质消化率等方面的影响还缺乏系统性研究。本文综述了国内外近20 年来关于蛋白质冻融交联、酶促交联及热加工交联的机理,探讨了交联作用对蛋白质功能性质、蛋白质消化率及其对蛋白类食品品质的影响。     

皮革化工材料知识及典型产品介绍（5）

戊二醛是一种优良的双官能团交联剂。它与蛋白发生交联反应的特点是交联性能好、结合量高，产物稳定．而且能较好地保持蛋白质的构型。在制革行业中戊二醛是一种很好的多性能鞣剂。     

基于蛋白质交联的氧化酶特性与应用

蛋白质交联属于蛋白质改性修饰的一部分,是重组食品与新型食品制造的重要内容。与化学交联、物理交联相比,酶法交联因其反应条件温和、不产生副产物、交联效果好等特点,成为最为容易接受的一种蛋白质交联方式。除谷氨酰胺转胺酶外,一些氧化酶也被证明能够在蛋白质分子间形成共价键而形成交联。介绍了目前应用较多的酚氧化酶(酪氨酸酶、漆酶)、过氧化物酶以及赖氨酰氧化酶的酶学性质、交联机制等,并对其在食品蛋白质交联中研究现状以及潜在应用进行总结与展望。     

大豆蛋白/壳聚糖凝聚法制备微藻油乳液及其稳定性研究

微藻油富含ω-3多不饱和脂肪酸二十二碳六烯酸(DHA)与二十碳五烯酸(EPA),在液体食品中的应用日趋广泛。但是微藻油极易在食品加工、保藏和消化过程中发生氧化劣变;同时脂溶性的微藻油难以添加至液体食品中。因此,改善和提高微藻油的稳定性是其应用到食品中的关键问题。本文利用大豆分离蛋白(SPI)/壳聚糖(CS)复合凝聚物(Coacervate)制备了微藻油乳液。由于乳液的氧化稳定性很大程度上依赖于其物理稳定性,本文系统研究了微生物谷氨酰胺转氨酶(m TGase)交联对微藻油乳液物理稳定性及氧化稳定性的影响。实验结果表明,在p H为6.0,CS/SPI比例为0.1 g/g,m TGase浓度为25 U/g SPI的条件下,m TGase对SPI/CS凝聚物的交联效果最好。m TGase交联明显改善了微藻油乳液的物理稳定性及氧化稳定性,并显著提高了微藻油的乳化效率。通过此方法制备的微藻油乳液产品可应用于豆奶等液体蛋白饮料从而达到强化DHA的目的。     

Transglutaminase cross-linking to enhance elastic properties of soy protein hydrogels with intercalated montmorillonite nanoclay

To strengthen the network of bio-nanocomposite hydrogels, layered montmorillonite (MMT) nanoclay was intercalated by surface-coating with soy protein (SP) before mixing with 6% w/v SP for cross-linking by microbial transglutaminase (mTGase). Dynamic rheology was performed to study variables of NaCl and mTGase concentrations, with and without 1% w/v MMT. Without mTGase, the highest storage modulus (G′) was observed at 100 mM for samples without MMT, which was twice of the highest G′ for samples with MMT, at 200 mM NaCl. With mTGase, a shorter gelation time and a stronger hydrogel were observed at a higher enzyme level. Overall, the non-gelling 6% w/v SP dispersion was transformed to a hydrogel with G′ of 1099 Pa after addition of 100 mM NaCl and 1% SP-coated MMT and treatments by 6.25 U/g-protein mTGase for 2 h and heating/cooling steps. The integration of surface-coating and mTGase cross-linking is promising to improve properties of the nanocomposite system.     

Innovative food processing technologies on the transglutaminase functionality in protein-based food products: Trends,opportunities and drawbacks

BackgroundConsumption of protein-based food products has a key role in the improvement of human health. The crosslinking agent microbial transglutaminase (mTGase) is an effective and promising tool to modify animal proteins used in the food industry. Improvement in the gelation process, physicochemical and textural quality, and consumer's demand of protein-based food products could be attained by combining mTGase and some non-conventional food processing technologies.Scope and approachNew perspectives and key areas for future research in the development of high-quality food proteins and protein-based products as a function of interaction effect of mTGase and some new processing techniques (e.g. high pressure processing (HPP), ultrasound, microwave (MW) and ultraviolet (UV) irradiation) are reviewed. The effect of conventional thermal and emerging processing methods on the mTGase crosslinking activity and protein gel functionality are also compared.Key findings and conclusionsThe crosslinking density and functional properties of protein gels can be strongly promoted by the synergistic action of mTGase and innovative processing methods. Compared to the conventional heating, HPP with further increase of mTGase affinity to proteins can result in products with better physicochemical quality and more complex and firmer gel structure. The yield, water holding capacity, surface hydrophobicity, strength, and viscoelastic characteristics of mTGase-catalyzed protein gels can be significantly increased by ultrasonication treatments. mTGase-crosslinked hydrogels subjected to high-intensity ultrasonic pretreatment have potential to be used as delivery vehicles for a wide spectrum of bioactive compounds. The application of MW and UV light can substantially improve the surface, textural and structural features of gels generated by mTGase-technology.     

Effect of Disulfide Bond Reduction on Bovine Serum Albumin-Stabilized Emulsion Gel Formed by Microbial Transglutaminase

ABSTRACT: Polymerization by microbial transglutaminase (mTGase) of disulfide bond-cleaved bovine serum albumin treated with 2-mercaptoethanol was investigated in an oil-in-water model emulsion system. Fluorescence and circular dichroism spectroscopy revealed that conformational changes in tertiary structure were more distinct as compared with the secondary structure. Reduced protein was polymerized more effectively by mTGase. Highest storage modulus was observed in the emulsion gel formed by both 2-ME and mTGase treatments. The phase angle was less than 45° in all samples with 2-ME and enzyme treatments, an indication that the conformational changes due to the reduction and polymerization contribute significantly to the formation of emulsion gels.     

Sequential preheating and transglutaminase pretreatments improve stability of whey protein isolate at pH 7.0 during thermal sterilization

Whey protein isolate (WPI) is a potential ingredient to manufacture shelf-stable transparent beverages if proteins are heat stable, i.e., without causing turbidity, precipitation and gelation after the required thermal processing to obtain commercial sterility (138 °C for 8 s or longer). However, information is lacking about stability of WPI during heating at 138 °C. Furthermore, novel technology and mechanistic understanding on how to produce clear products after heating systems with >5% WPI, particularly with salt, is needed. In this work, 5% w/v WPI was pretreated by microbial transglutaminase (mTGase) at three levels for 1–15 h at 50 °C, with and without prior preheating at 80 °C for 15 min. Heat stability of the pretreated samples at pH 7.0 and 0, 50, and 100 mM NaCl was evaluated at 138 °C. Samples pretreated by mTGase for a greater extent demonstrated improved heat stability. Samples subjected to sequential preheating and mTGase pretreatments produced clear dispersions even after heating at 138 °C for 30 min in the presence of 0 and 50 mM NaCl at pH 7. All pretreatments increased the magnitude of zeta-potential and resistance against thermal denaturation. The sequentially-pretreated WPI was the most heat-resistant, having decreased hydrodynamic diameter (<36 nm) during extended heating at 138 °C and 50 mM NaCl. The present study demonstrates the feasibility of using sequential preheating and mTGase pretreatments to develop sterilized beverage products with a high content (5% w/v) of whey protein and yet of transparent appearance at ambient temperatures.     

Nutritional,Health, and Technological Functionality of Lupin Flour Addition to Bread and Other Baked Products: Benefits and Challenges

Lupin is an undervalued legume despite its high protein and dietary fiber content and potential health benefits. This review focuses on the nutritional value, health benefits, and technological effects of incorporating lupin flour into wheat-based bread. Results of clinical studies suggest that consuming lupin compared to wheat bread and other baked products reduce chronic disease risk markers; possibly due to increased protein and dietary fiber and bioactive compounds. However, lupin protein allergy has also been recorded. Bread quality has been improved when 10% lupin flour is substituted for refined wheat flour; possibly due to lupin-wheat protein cross-linking assisting bread volume and the high water-binding capacity (WBC) of lupin fiber delaying staling. Above 10% substitution appears to reduce bread quality due to lupin proteins low elasticity and the high WBC of its dietary fiber interrupting gluten network development. Gaps in understanding of the role of lupin flour in bread quality include the optimal formulation and processing conditions to maximize lupin incorporation, role of protein cross-linking, antistaling functionality, and bioactivity of its γ-conglutin protein.     

Characteristics of Sodium Caseinate- and Soy Protein Isolate-Stabilized Emulsion-Gels Formed by Microbial Transglutaminase

ABSTRACT:  Protein-stabilized emulsion gels were prepared via microbial transglutaminase (mTGase) catalysis, and their physicochemical characteristics were examined. Emulsion oil droplet size and interfacial protein load were measured. The sodium caseinate and soy protein isolate emulsion gels exhibited different microstructures and physical properties. The emulsion gels improved the storage stability of aroma compounds. Rheological measurements of the emulsion gels revealed interesting strength, gelation kinetics, and thermal sensitivity properties. The mTGase-induced emulsion gels comprised a fine network which led to less release of aroma compounds upon storage than did emulsions. These results suggest that emulsion gels may be used to improve the texture of food emulsions and to control release of food aromas.     

豆类蛋白组装机制及其与蛋白加工特性关联性的研究进展

随着植物基食品消费市场的快速发展,豆类蛋白作为可持续蛋白质资源以及动物蛋白的替代品,在健康食品产业发挥着重要作用。蛋白质组装作为一种有效驱动蛋白质自身及与大分子物质间相互作用的策略在豆类蛋白食品的高效加工中至关重要。概述了pH值、温度、离子、交联酶以及大分子物质等不同条件促使豆类蛋白聚集组装的作用机制以及组装行为与蛋白加工特性之间的关联性。pH值会决定蛋白表面电荷的类型及分布,改变蛋白质的二级结构,促进蛋白质的组装;温度升高不仅使豆类蛋白暴露出某些基团,还可以提高蛋白质扩散和碰撞的速率,加速蛋白质的组装;离子类型及强度分别影响蛋白质周围水的分布及蛋白质间的静电作用,诱导组装行为的发生;交联酶催化豆类蛋白分子内或分子间发生交联,从而驱动豆类蛋白进行聚集组装;多糖和酚类等大分子物质通过与豆类蛋白相互结合,改变蛋白质的结构,为蛋白质的聚集组装提供条件。另外,阐述了豆类蛋白的组装行为对豆类蛋白的加工特性,包括乳化性、发泡性、凝胶性和成膜性的影响,分析了微观变化与加工特性之间的关联性。对豆类蛋白进一步高效利用的发展方向进行了展望,以期为更好地开发高品质的豆类蛋白产品提供理论依据。     

谷氨酰胺转氨酶对山杏仁蛋白凝胶特性的影响

为提高山杏仁蛋白的凝胶特性,采用谷氨酰胺转氨酶(TG酶)作为交联剂,通过单因素实验研究了TG酶添加量、pH、交联温度、交联时间对蛋白凝胶硬度、弹性、内聚力的影响,并以凝胶强度为指标,利用响应面法对山杏蛋白形成条件进行优化。优化的TG酶交联山杏仁蛋白形成凝胶的条件如下:TG酶添加量17 U/g,交联温度43℃,pH为7.2,交联时间2.5 h时,此时凝胶硬度达到(135±7.14) g。结果表明利用TG酶交联山杏仁蛋白形成凝胶具有可行性,为提高山杏仁蛋白的功能性质和应用价值提供参考。     

肌原纤维蛋白转谷氨酰胺酶交联程度对鱼糜凝胶及其风味释放影响的研究进展

转谷氨酰胺酶可以催化肌原纤维蛋白发生交联反应。随着交联程度的增加,鱼糜凝胶从弹黏体变为弹脆体,风味也随之改变。风味物质的扩散、释放与凝胶网络的交联程度密切相关,因此深入了解交联程度与食品品质的关系及风味物质在凝胶网络中的扩散行为显得尤为重要。本文总结转谷氨酰胺酶催化肌原纤维蛋白的交联机理,归纳了国内外对肌原纤维蛋白交联程郭彩霞度的测定方法与影响因素,探讨交联程度对鱼糜蛋白的凝胶特性与风味释放的影响,并对今后的研究方向提出思考与展望。