漆酶在食品分子修饰和食品胶体体系中的应用

近年来,改善食品分子的功能和营养特性一直是研究的热点。食品分子的酶促修饰可用于增强其在食品中的功能性质。漆酶可催化蛋白质、多糖和多酚的氧化,在食品分子以及食品胶体的构建中具有巨大的应用潜力。文章总结了漆酶的结构、来源、对食品分子修饰的催化机制及其在食品胶体体系中的应用。研究发现漆酶分两步催化食品分子的氧化：第一步涉及产生自由基或醌的酶促反应;第二步涉及自由基或醌与其他分子的非酶促反应。漆酶在整个过程中主要起着引发反应的作用。由漆酶诱导的食品分子交联有助于改善食品分子的性质和功能,从而增加食品分子的功能性质、扩展用途,以及改善食品胶体体系(如乳液、纳米颗粒和微凝胶)的形成和稳定性,从而增强它们封装、保护和递送生物活性化合物的潜力。     

转谷氨酰胺酶对食品的粘合作用

<正> 在加工食品中添加酶以改变制成品的性质,是非常普遍的做法。一般加工食品所采用的酶,如淀粉酶和蛋白酶等,其作用在于把食品中较粗糙的成分分解成较微小的颗粒。但转谷氨酰胺酶的作用却相反——它利用蛋白质与蛋白质之间会互相形成共价键的特性,催化食品中蛋白质的聚合作用和交联反应(蛋白质交联模拟图见于图一),从而使小块状食品粘合成理想的形状,并改进其硬度和弹性,提高食品的感观质量。 转谷氨酰胺酶基本上存在于哺乳类动物的肝脏和血液之中,也存在于鱼类的肌肉内,甚至在微生物中。作为工业     

酪蛋白与明胶的酶促交联与产物的流变学性质

利用转谷氨酰胺酶对酪蛋白和明胶进行酶促混合交联。在酪蛋白与明胶比例为4︰1(质量比)时,以交联产物中羟脯氨酸质量分数为指标,采用单因素试验研究酶添加量、反应时间和温度对交联反应的影响。优化后的适宜交联条件为:底物质量浓度固定为50 g/L,酶添加量为每克蛋白质20 U,反应时间为4 h,温度为45℃。SDS-聚丙烯酰胺凝胶电泳分析表明产物中含有蛋白质聚合物。与原料酪蛋白、转谷氨酰胺酶促交联的酪蛋白相比,所得到的产物的分散液表观黏度和黏弹性均有显著的改变,表明转谷氨酰胺酶催化的酪蛋白和明胶混合可以用于改善其流变学性质。     

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。     

谷氨酰胺转氨酶催化蛋白质糖基化的研究进展

谷氨酰胺转氨酶(TGase)作为生物催化剂,催化蛋白质中γ-谷氨酰胺残基与带有伯氨的糖共价结合,从而改善蛋白的功能特性,减少美拉德反应中副产物的形成。综述了谷氨酰胺转氨酶酶促糖基化的反应机理、作用形式及其产物在食品中的应用,并对谷氨酰胺转氨酶催化蛋白质糖基化的发展前景进行了展望。     

酶促类蛋白反应的研究进展

酶促类蛋白反应是指将浓缩的蛋白水解物,在适宜的条件下,经蛋白酶催化成蛋白质类似物的过程。酶促类蛋白反应不仅可以弥补天然蛋白质在氨基酸组成上的缺陷,提高蛋白质功能性,改善蛋白水解物的风味,为科研和生产提供新的蛋白质来源,而且利用该方法获得的产品生物利用率高,无毒副作用,所以受到了科学界的广泛关注并逐渐被应用到食品工业之中。本文综述了酶促类蛋白反应的机理、影响因素、产物特性及其在食品领域的应用,以期为食品品质的改善提供新的方法,为新型食品的开发提供新的途径。     

逆胶束酶系统及其在食品工业中的应用

ReverseMicellesEnzymeandItsApplicationinFoodEngineeringHuangHongzhiZhaoGuohuaWangYaxi酶工程中,酶的固定化是一种非常重要的技术,主要方法包括吸附法、包埋法、结合法和交联法等。近年来,又兴起一种逆胶束固定化酶技术。食品工业所用酶大多是水溶性蛋白质,酶反应通常是在水相中进行,但是有些酶反应若在有机相中进行,将会有较大的好处。例如,当废物或产物是亲脂性物质时,或者反应条件要求低水环境时,采用有机介质就能获得较高的底物和产物浓度,并能减少产物抑制一些水相酶反应中的麻烦。此时若将酶固定在逆胶束（rever…     

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。     

转谷氨酰胺酶的特性及其聚合大豆蛋白的研究

转谷氨酰胺酶作为一种生物催化剂,可以催化蛋白质赖氨酸上ε-氨基和谷氨酰胺上γ-羟酰胺基之间的交联反应,在蛋白质分子间或分子内形成ε-(γ-谷氨酰胺基)赖氨酸(G-L)键。此催化过程具有反应条件温和、底物选择性好的特点,交联聚合后蛋白的功能特性,如凝胶性、热稳定性和保水性等会得到明显改善,因此,其广泛应用于动植物蛋白的改性中。本文介绍了不同来源转谷氨酰胺酶的特性和其在不同食品体系中的作用,并对转谷氨酰胺酶催化大豆蛋白聚合的研究进行了综述。     

食品加工中晚期糖基化终产物的变化趋势及茶多酚对其抑制作用

晚期糖基化终产物(AGEs)是食品加工和贮藏中美拉德反应、脂质氧化反应或葡萄糖氧化等多种途径中的产物,在人体内积累后能够引起一些慢性疾病,如糖尿病、肾病、高血脂等,因此抑制晚期糖基化终产物具有重要意义。采用葡萄糖(Glc)与牛血清白蛋白(BSA)模拟食品加工中产生的糖基化产物反应过程,以茶多酚为抑制剂加入反应体系中,通过NBT法测定果糖胺,高效液相色谱法(HPLC)测定乙二醛(GO)和羧甲基赖氨酸(CML),荧光法测定AGEs来检测糖基化反应的早、中期和晚期产物,根据蛋白质羰基和巯基含量和蛋白质相对分子质量变化,获得茶多酚抑制晚期糖基化终产物的主要机制。试验结果表明:在食品加工条件下茶多酚对糖基化反应的中间产物果糖胺、乙二醛有明显抑制作用,对CML和荧光性AGEs有一定抑制作用。SDS-聚丙烯酰胺凝胶电泳表明茶多酚与蛋白质的相互作用引起蛋白质二级结构的变化,阻止蛋白质交联。结合茶多酚对蛋白质巯基的保护作用,茶多酚既以抗氧化作用参与抑制糖基化反应,又对蛋白质的交联反应有抑制作用。     

酶法提取多糖的研究进展

多糖是一种广泛存在于生命体内的大分子聚合物,部分多糖具有提高免疫力、抗氧化、抗凝血、抗癌、抗病毒、降血糖等生物活性,在食品、医疗、化工等众多领域发挥着重要的作用。与多糖的其他提取方法相比,酶法提取具有反应条件温和、提取效率高、产物活性强、成本低、节能环保等特点。本文论述了近年来酶法提取多糖的研究进展,主要包括酶法提取多糖的原理及其影响因素、单种酶法提取、多种酶法提取、酶法提取技术与其他技术的联用以及多糖酶提取法的优势,并对该方法的应用前景进行展望。     

多功能木聚糖水解酶的研究及其在食品领域的潜在应用

木聚糖是植物细胞壁中含量最丰富的异质多糖,具有合成高值化生物基产品的巨大潜力。在食品领域,木聚糖经高效酶解转化可产生低聚木糖、木糖醇、阿魏酸等功能性食品多糖。与多酶协同催化相比,兼具多种木聚糖水解酶活性的多功能酶具有生产成本低、催化效率高、酶解工艺简化等显著优势,具有广阔的应用前景。作者首先介绍了不同植物来源木聚糖的结构组成及主链与侧链降解酶系,进而系统综述了近年来多功能木聚糖水解酶在结构、功能及作用机理方面的研究进展及在食品领域中的应用潜力,最后展望了多功能木聚糖水解酶的研究方向,为多功能木聚糖水解酶的精准设计及产业化应用奠定基础。     

酶法提取黑木耳多糖

研究了酶法提取黑木耳多糖的最佳工艺条件。以提取率为指标,分别考察了浸提剂倍数、酶解pH、温度、时间、加酶量对果胶酶或纤维素酶酶解反应的影响。试验确定了果胶酶酶解木耳的最佳工艺条件:浸提剂倍数50,pH5.0,温度55℃,时间80min,酶加量1.1%,在此条件下,黑木耳多糖的提取率为4.15%;纤维素酶酶解木耳的最佳工艺条件:浸提剂倍数50,pH5.0,温度50℃,时间80min,酶加量为1.3%,黑木耳多糖的提取率为4.71%。     

海藻寡糖的生理活性与酶法转化研究进展

我国海藻资源极其丰富,但目前其利用主要集中于食品、饲料和保健品生产等少数方面,海藻资源的高值化利用途径有待进一步开发。海藻多糖是海藻细胞壁重要组分,具有多种生物活性功能,但因其聚合度高、黏度大、溶解性差,很难被机体吸收利用。海藻多糖经物理、化学、生物等方法可降解为海藻寡糖,其溶解性和生理学活性显著提升,更适合应用于食品、保健品、饲料、农业等诸多领域。基于酶法开发海藻寡糖绿色制备技术,具有传统方法不可比拟的优势,效率高、成本低、污染少。作者综述了褐藻寡糖、琼胶寡糖、卡拉胶寡糖、岩藻寡糖等海洋寡糖的生理活性及酶法转化的研究进展,为海藻资源的高值化利用提供新思路。     

Effect of extraction techniques and conditions on the physicochemical properties of the water soluble polysaccharides from gold kiwifruit (Actinidia chinensis)

The extraction of nonstarch polysaccharides from fruits and vegetables has received much attention recently in terms of their utilisation in functional food systems. In New Zealand kiwifruit production is one of the major fruit growing exploits. This paper explores the potential extraction techniques which may be employed to extract water soluble polysaccharides from kiwifruit material, in an attempt to utilise this commodity as an added value food ingredient. Crude water soluble polysaccharides of fresh gold kiwifruit were extracted under different extraction techniques (acid, hot water and enzyme) and conditions (time, temperature and concentration). The recovery of water soluble polysaccharide fraction (WSP), chemical composition, and their rheological behaviour were examined. The extraction technique had a significant effect on the WSP yield, galacturonic acid content, as well as the viscosity. Enzymatic extraction method yielded higher WSP and galacturonic acid than water and acid extraction, but this fraction exhibited lower viscosity. Acid extracted WSP yield decreased with increasing temperature and time. In contrast, water extracted WSP yield increased with increasing temperature and time. The selected extraction parameters for acid extraction were temperature 50 °C, extraction time 60 min, and 1:6 kiwifruit puree to acid solution ratio. The water extraction optimum parameters were 25 °C, 30 min and 1:4 puree to water ratio and 25 °C, 30 min with medium concentration for enzymatic extraction. The WSP viscosity and galacturonic acid content was maximum under these extraction conditions.     

A comprehensive review on polarity,partitioning, and interactions of phenolic antioxidants at oil–water interface of food emulsions

There has been a growing interest in developing effective strategies to inhibit lipid oxidation in emulsified food products by utilization of natural phenolic antioxidants owing to their growing popularity over the past decades. However, due to the complexity of emulsified systems, the inhibition mechanism of phenolic antioxidants against lipid oxidation is rather complicated and not yet fully understood. In order to highlight the importance of polarity of phenolic antioxidants in emulsified systems according to the polar paradox, this review covers the recent progress on chemical, enzymatic, and chemoenzymatic lipophilization techniques used to modify the polarity of antioxidants. The partitioning behavior of phenolic antioxidants at the oil–water interface, which can be influenced by the presence of synthetic surfactants and/or antioxidant emulsifiers (e.g., polysaccharides, proteins, and phospholipids), is discussed. In addition, the emerging phenolic antioxidants among phenolic acids, flavonoids, tocopherols, and stilbenes applied in food emulsions are elaborated. As well, the interactions of polar–nonpolar antioxidants are stressed as a promising strategy to induce synergistic interactions at oil–water interface for improved oxidative stability of emulsions.     

酶法提取黄芪多糖的工艺优化

运用Box-Behnken中心组合响应面分析法优化纤维素酶法提取黄芪多糖的工艺条件,探讨了酶解过程中酶解pH值、温度和加酶量对多糖提取含量的影响。优化工艺方案为:酶解pH4.0,温度56.5℃,加酶量61U/ g,其多糖的平均含量达到20.31%。     

地黄多糖提取工艺、生物活性及机制研究进展

今年来中药多糖的生物活性备受关注,研究也愈发深入。其中,地黄作为我国传统药食两用植物,在我国已有两千多年的食用历史。地黄多糖作为地黄的主要活性成分之一,具有增强免疫功能、抗氧化、抗肿瘤、调节血糖血脂等功效,在功能性食品与添加剂的开发中有很高的应用价值。目前,地黄多糖的提取工艺主要有水提醇沉法、超声热浸提法、酶解提取法,微波提取法、超临界萃取和复合提取法等,不同提取工艺对地黄多糖提取率影响也各不相同。此外,本文重点从抗氧化、抗肿瘤、降低血糖血脂、抗焦虑/抑郁和缓解衰老等方面系统阐述地黄多糖的生物活性及其作用机制,并对地黄多糖应用于食品与医药领域进行展望,为地黄多糖的研究以及后续深度开发利用提供参考。     

Tuning the Functional Properties of Polysaccharide–Protein Bio‐Based Edible Films by Chemical,Enzymatic, and Physical Cross‐Linking

Among natural biopolymers, polysaccharides and proteins are very promising for biodegradable and edible wraps with different characteristics, so that their formulations can be tailor‐made to suit the needs of a specific commodity. Films prepared from polysaccharides have good gas barrier properties but exhibit lower resistance to moisture compared to protein films (edible) or polylactide films (biodegradable). Protein‐based films show better mechanical and oxygen barrier properties compared to polysaccharide films. For that reason, film performances may be enhanced by producing blend systems, where hydrocolloids (mixtures of proteins and/or polysaccharides) form a continuous and more cohesive network. However, the lower water barrier properties of hydrocolloid films and their lower mechanical strength in comparison with synthetic polymers limit their applications in food packaging. Therefore, the enhancement of biopolymer film properties has been studied to attain appropriate applications. This review provides an extensive synthesis of the improvement of the properties of edible polysaccharide–protein films by way of various chemical, enzymatic, and physical methods. These methods primarily aim at improving the mechanical resistance. They also permit to ameliorate the water and gas barrier properties and related functional properties.     

Food‐Grade Covalent Complexes and Their Application as Nutraceutical Delivery Systems: A Review

Food proteins, polysaccharides, and polyphenols are 3 major food constituents with distinctly different functional attributes. Many proteins and polysaccharides are capable of stabilizing emulsions and foams, thickening solutions, and forming gels, although they differ considerably in their abilities to provide these functional attributes. Many plant polyphenols exhibit beneficial physiological functions, such as antitumor, antioxidant, antibacterial, and antiviral properties. Proteins, polysaccharides, and polyphenols can form complexes with each other, which leads to changes in the functional and nutritional properties of the combined systems. Recently, there has been considerable interest in understanding and utilizing covalent interactions between polyphenols and biopolymers (proteins and polysaccharides). The binary or tertiary conjugates formed may be designed to have physicochemical properties and functional attributes that cannot be achieved using the individual components. This article provides a review of the formation, characterization, and utilization of conjugates prepared using proteins, polysaccharides, and polyphenols. It also discusses the relationship between the structural properties and functionality of the conjugates, and it highlights the bioavailability of bioactive compounds loaded in conjugate‐based delivery systems. In addition, it highlights the main challenges to be considered when preparing and analyzing conjugates. This article provides an improved understanding of the chemical reactions that occur between major food ingredients and how they can be utilized to develop biopolymer‐based delivery systems with enhanced functional attributes.