改善食品质构的直接交联酶

食品交联酶对于食品的质构改善有着重要的影响,在烘焙制品等食品生产中发挥着巨大的作用。此文介绍了改变食品质构的几类直接交联酶的性质、交联机理以及在食品生产上的具体应用和展望。      

TG酶和漆酶对双歧杆菌益生菌酸奶品质的影响

为了比较谷氨酰胺转氨酶(TG酶)和漆酶的添加对双歧杆菌益生菌酸奶感官、蛋白质交联及组织质构变化的影响,测定和分析了两种酶交联益生菌酸奶的游离氨基变化率、感官、质构、表观黏度、蛋白条带及微观结构,并添加阿魏酸改善漆酶酸奶的品质。结果表明:当TG酶用量增加时,TG酶交联酸奶的游离氨基变化率、感官得分和硬度显著增大(p<0.05),胶黏性、粘聚性及表观黏度先增大后减小(p<0.05),内聚性变化不显著(p>0.05),TG酶最佳用量为1.8 U/g;随着漆酶用量的增加,漆酶酸奶游离氨基变化率、感官得分、硬度、内聚性、胶黏性、粘聚性及表观黏度均先增大后减小(p<0.05),漆酶最佳用量为0.3 U/g;添加4.5 mmol/L的阿魏酸明显改善了漆酶交联酸奶的感官、质构及表观黏度;所有待测酸奶中均缺少β-lg条带,TG酶交联酸奶的κ-CN和β-CN条带消失,聚集成了新的蛋白质,而漆酶交联酸奶和阿魏酸+漆酶酸奶与对照及TG酶酸奶相比,分子量在14 kDa的蛋白条带明显变宽;经两种酶交联的酸奶,三维网络结构变得致密,TG酶交联酸奶的胶粒分布更均匀,网络结构更致密,且在漆酶交联酸奶中添加了阿魏酸后,相较于漆酶交联酸奶,蛋白胶束聚集的更紧密,从而得出,不同类型酶对牛奶乳蛋白质交联的催化作用不同,但均可改善酸奶的感官及食用品质。     

亲水多糖对谷氨酰胺转氨酶交联大豆分离蛋白凝胶特性的影响

目的 基于谷氨酰胺转氨(transglutaminase, TG)酶交联法研究亲水多糖对TG酶交联大豆分离蛋白凝胶特性的影响。方法 以大豆分离蛋白为主要原料,TG酶交联法为基础进行响应面优化,得到最优凝胶弹性的工艺参数,在此参数条件下将大豆分离蛋白与亲水多糖混合,制备亲水多糖-大豆分离蛋白复合凝胶,并对凝胶的质构特性、持水性、热力学性质以及结构进行表征。结果 在酶交联pH 7.3、酶交联时间2.3 h、酶交联温度48℃条件下,制备的大豆分离蛋白凝胶弹性最佳。添加了亲水多糖后,凝胶的质构特性和持水性显著提高,热稳定性增强,蛋白质二级和三级结构发生变化,凝胶的微观结构变得更致密,孔径变小。结论 亲水多糖的添加能够改善大豆分离蛋白的凝胶特性,该研究为大豆分离蛋白凝胶深加工提供了理论基础。     

漆酶在食品工业中的研究与应用进展

漆酶在食品工业中的研究与应用正日渐广泛与深入。率先对该领域的众多成果进行了整理,对漆酶在饮料加工、食药用菌生产、食品分子交联、植物食品保护等方面的重要作用进行了分类综述。     

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。     

中国老年专用食品需求及其质构分级与测试方法分析

目的：基于人口老龄化问题,分析老年专用食品的市场需求及其质构分级和测试方法。方法：通过文献查阅与分析提出老年专用食品的市场需求,综述不同国家与组织对于食品质构相关标准的制定情况以及当前食品质构的测试方法,提出老年专用食品产业化生产在质构调整方面的技术难点。结果：我国社会对老年专用食品具有极大需求,但相关食品质构特征参数与测试方法有待进一步明晰,尚无法指导生产。结论：我国老年专用食品发展空间广阔,但相关基础研究仍待加强,产品质量标准尚待建立。     

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。     

食品改良剂对速冻熟制拉面质构特性的影响

该文以高筋粉为原料制作速冻拉面,研究了多种食品改良剂对速冻拉面质构特性的影响。结果表明:适量添加食用碱、瓜尔豆胶、黄原胶、谷氨酰胺转氨酶(TG酶)或硬脂酰乳酸钠(SSL)可以明显增加拉面的拉断力和拉伸距离,从而改善拉面的延伸性。食盐、食用碱、黄原胶、TG酶、葡萄糖氧化酶(GOD)、木薯交联淀粉和马铃薯醋酸酯淀粉对拉面的硬度增加有重要贡献。添加黄原胶、瓜尔豆胶或TG酶可以明显增加拉面的弹性。此外,食用碱和TG酶能够有效改善拉面的黏聚性和回复性。对速冻熟制拉面整体质构特性改良效果较好的添加剂有食盐、食用碱、瓜尔豆胶、黄原胶和TG酶。     

乳清蛋白改性综述

通过改性可以加强乳清蛋白的功能性质，从而扩大它在食品中的应用范围。乳清蛋白的改性方法有化学法、酶法和物理法．化学改性包括酸化、酰胺化、酯化、磷酸化、硫醇化、还原烷基化和共价连接氨基酸等；酶改性主要为部分水解，蛋白质分子内或分子间交联以及连接功能基团；物理改性有热变性，与大分子聚合和质构化等．     

Extremozymes from metagenome: Potential applications in food processing

The long-established use of enzymes for food processing and product formulation has resulted in an increased enzyme market compounding to 7.0% annual growth rate. Advancements in molecular biology and recognition that enzymes with specific properties have application for industrial production of infant, baby and functional foods boosted research toward sourcing the genes of microorganisms for enzymes with distinctive properties. In this regard, functional metagenomics for extremozymes has gained attention on the premise that such enzymes can catalyze specific reactions. Hence, metagenomics that can isolate functional genes of unculturable extremophilic microorganisms has expanded attention as a promising tool. Developments in this field of research in relation to food sector are reviewed.     

酶解-交联法制备多孔淀粉及其负载红景天苷研究

以玉米淀粉为原料,采用α-淀粉酶和糖化酶复合酶解与三偏磷酸钠交联改性相结合的方法制备了一系列具有不同交联度的交联多孔淀粉。通过各种表征手段考察了原玉米淀粉、多孔淀粉和交联多孔淀粉的形态结构和理化性质,并应用于负载红景天苷研究。该方法制备的交联多孔淀粉具有良好的蜂窝状中空结构,有利于淀粉颗粒对目的物质的吸附。相比原淀粉和未交联多孔淀粉,交联多孔淀粉的吸油率有较大提高,对红景天苷的包封率为58.89%。经过交联反应后的交联多孔淀粉不但晶型没有发生改变,还具有更高的总孔面积、平均孔直径和孔隙率值,其分子结构也更加紧凑,更具刚性和更高的糊化温度,说明交联改性提高了多孔淀粉的结构性能。体外释放结果表明载药交联多孔淀粉具有一定的缓释性能,能够提高红景天苷的生物半衰期和生物利用度。      

Enzymatic crosslinking and food allergenicity: A comprehensive review

Food allergy has become a major global public health concern. In the past decades, enzymatic crosslinking technique has been employed to mitigate the immunoreactivity of food allergens. It is an emerging non-thermal technique that can serve as a great alternative to conventional food processing approaches in developing hypoallergenic food products, owing to their benefits of high specificity and selectivity. Enzymatic crosslinking via tyrosinase (TYR), laccase (LAC), peroxidase (PO), and transglutaminase (TG) modifies the structural and biochemical properties of food allergens that subsequently cause denaturation and masking of the antigenic epitopes. LAC, TYR, and PO catalyze the oxidation of tyrosine side chains to initiate protein crosslinking, while TG initiates isopeptide bonding between lysine and glutamine residues. Enzymatic treatment produces a high molecular weight crosslinked polymer with reduced immunoreactivity and IgE-binding potential. Crosslinked allergens further inhibit mast cell degranulation due to the lower immunostimulatory potential that assists in the equilibration of T-helper (Th)1/Th2 immunobalance. This review provides an updated overview of the studies carried out in the last decade on the potential application of enzymatic crosslinking for mitigating food allergenicity that can be of importance in the context of developing hypoallergenic/non-allergenic food products.     

Natural biopolymer-based hydrogels for use in food and agriculture

Hydrogels are important materials that are of high scientific interest and with numerous applications. Natural polymer-based hydrogels are preferred to synthetic ones due to their safety, biocompatibility, and ecofriendly properties. They have been studied extensively and implemented in various fields, such as medicine, cosmetics, personal-care products, water purification, and more. This review focuses on the applications of nature-sourced polymer-based hydrogels in food and agriculture. Different types of biopolymers and crosslinking agents, and various methods for hydrogel formation are described. The physicomechanical properties and applied activities of the resulting materials are also comprehensively discussed. Biodegradable synthetic polymers are outside the scope of this review. © 2020 Society of Chemical Industry     

Crosslinking of wheat dough proteins by glucose oxidase and the resulting effects on bread and croissants

The crosslinking of wheat flour proteins results in significant improvements in the functional properties of baked products. In this research, the enzyme glucose oxidase was investigated for its crosslinking effect on the dough proteins of bread and croissants. The macroscopic effects resulting from the addition of glucose oxidase to the dough formulation were compared to changes seen at the molecular level in individual protein fractions. Treatment with glucose oxidase produced slight improvements in crumb properties but no increase in product volume. At the molecular level, crosslinking occurred mainly in the water-soluble (albumin and globulin) fraction and was demonstrated to involve both disulfide and non-disulfide linkages. The SDS-soluble and -insoluble glutenins, which make up much of the gluten network, were crosslinked to a much lesser extent, with mainly non-disulfide linkages. These findings corroborate our theories on the relationship of wheat protein crosslinking and functional properties. Specifically, we conclude that (i) crosslinking of albumin and globulin proteins enhances crumb properties and (ii) changes in croissant volume require crosslinking of the glutenin fraction of wheat proteins.     

西米交联淀粉的理化性质

以三偏磷酸钠为交联剂,采用水分散法制备西米交联淀粉,利用扫描电镜、聚焦光束发射测量仪、Bra-bender快速黏度计和紫外分光光度计对其性质进行测定和分析,并与西米原淀粉进行比较。结果表明:西米交联淀粉发生了中等程度的交联;西米交联淀粉保持了西米原淀粉绝大多数颗粒完整、呈椭圆形、存在断切面和断切面处有凹坑的形貌特征,但其表面比较粗糙,有凹痕,且断切面处凹坑更加明显;西米交联淀粉颗粒粒径分布图呈单峰,在水相中的平均粒径为30.1μm,比西米原淀粉颗粒小;西米交联淀粉比西米原淀粉难于糊化,其热稳定性和冷糊稳定性均优于西米原淀粉,有很高的最终黏度;西米交联淀粉的透光率为5.1%,小于西米原淀粉,其透明度较差。     

碳化二亚胺/羟基丁二酰亚胺交联改性胶原蛋白纤维制备及其性能

为解决由湿法纺丝工艺制备的牛肌腱胶原蛋白纤维力学性能差、遇水易溶解等问题,采用1-乙基-3-(3-二甲基丙基)碳化二亚胺盐酸盐/N-羟基丁二酰亚胺(EDC/NHS)对胶原蛋白纤维进行交联改性。探究了原位交联方式的最优交联时间和交联剂质量分数,并着重对比了原位交联与交联浴交联2种交联方式对胶原蛋白纤维性能的影响。结果表明:原位交联可显著改善胶原蛋白纤维的性能,最优的交联时间和交联剂质量分数分别为11 h、15%,此时纤维断裂强度可达1.44 cN/dtex左右,较纯胶原蛋白纤维提高了35.8%,较交联浴交联纤维提高了19.0%;与主要发生在纤维表面的交联浴交联相比,原位交联能够使纤维内部的微纤结构更加致密,性能得到更为显著的提升,由原位交联制备的胶原蛋白纤维性能优于交联浴交联制备的纤维。     

Application of enzymes in food processing

Enzymes offer potential for many exciting applications for the improvement of foods. There is still, however, a long way to go in realizing this potential. Economic factors such as achievement of optimum yields and efficient recovery of desired protein are the main deterrents in the use of enzymes. Changing values in society with respect to recombinant DNA and protein engineering technologies and the growing need to explore all alternative food sources may in time make enzyme applications more attractive to the food industry. Research is continuing on the commercially viable enzymes in use today to improve various properties such as thermostabilities, specificities, and catalytic efficiencies. New and unique enzymes continue to be developed for use in enzymatic reactions to produce food ingredients by hydrolysis, synthesis, or biocatalysis. An aggressive approach is needed to open new opportunities for enzyme applications that can benefit the food industry.     

转谷氨酰胺酶的性质、制备及在食品加工中的应用

转谷氨酰胺酶是催化蛋白质分子之间交联的一种酶，对蛋白质的成胶能力、热稳定性、持水能力等功能特性有独特的改善作用。目前从微生物Streptoverticillium spp．中分离转谷氨酰胺酶和在食品工业中的实际应用都已经实现，因为从微生物制备可以实现大规模的工业化生产，成本低廉，为转谷氨酰胺酶在工业上的应用奠定了基础。现在转谷氨酰胺酶广泛地应用于海洋食品、面条／面团、奶制品、烘焙食品等食品加工领域，通过温和的酶反应可以明显地改善食品的硬度、弹性、热稳定性和持水能力。主要讨论了转谷氨酰胺酶的性质、分离和在食品加工中的应用。     

超声技术在食品工业中的研究进展

超声技术在食品工业中的应用可分为两类:检测超声技术和功率超声技术。检测超声技术为一非破坏性检测技术,可以用来分析检测食品体系中的组成、质构、流变学性质等物化性质。功率超声主要用于食品的物理和化学改性,如活化酶、促进乳化、加速结晶、嫩化肉和有效成分的快速提取等。