Dairy enzymology

The properties and the significance of the principal indigenous enzymes in milk, milk coagulants, enzymes from dairy microorganisms participating in cheese ripening, and spoilage enzymes are discussed. In particular, the properties of plasmin, lipases, phosphatases, enzymes from somatic cells, enzymes involved in antimicrobial and antiviral systems in milk, enzymes from lactic acid bacteria, propionibacteria, and microorganisms involved in smear- and mould-ripened cheese are reviewed. Some assay methods and the impact of some processing factors on selected enzymes are also discussed.     

粥化酶及其在果蔬加工中的应用研究

研究了粥化酶的粗酶特性及其在果蔬加工中的应用，并比较了粥化酶与其它果蔬加工用酶在苹果加工中的应用效果。研究结果表明粥化酶作用的最佳条件符合果蔬加工的要求，它能够不同程度的提高果蔬的出汁率及其澄清度；与其它果蔬加工用酶相比粥化酶具有作用效果好，价格便宜的优点     

D-塔格糖-3-差向异构酶及其应用

D-塔格糖-3-差向异构酶（D-tagatose-3-epimerase,DTE）家族,是催化酮糖类单糖C-3位置的差向异构化反应的一类酶,也是稀有糖生产中的核心酶.随着稀有糖在食品、保健品、医药中间体等领域的广泛应用,利用DTE酶家族制备稀有糖备受关注.本文对DTE酶家族的DTEase和DPEase的来源、酶学特性、蛋白结构以及DTE酶家族在稀有糖生产中的应用现状等方面进行了综述,最后对DTE酶家族的研究趋势进行了展望.     

面包添加剂中酶制剂混合均匀度研究

酶制剂混合均匀度是添加酶制剂的产品生产质量控制的一个关键因素。研究了面包添加剂中酶制剂混合均匀度的测定方法。采用酶制剂与钙盐预混合配制面包添加剂，测定灰分含量，其变异系数能反映酶制剂混合均匀度。     

Metaproteomic analysis of enzymatic composition in Baobaoqu fermentation starter for Wuliangye baijiu

Wuliangye is one of the most famous brands of baijiu in China. The typical flavours of Wuliangye baijiu are mainly formed by the multifarious enzymes in fermentation starter (Baobaoqu, BBQ). As the enzymes remained poorly understood, the detailed enzymatic composition of BBQ was analysed by metaproteomics for the first time. It is worth noting that the enzymes from plant, animals and micro-organisms were detected together and oxidoreductases were the dominant enzymes. Next, the analysis of function showed that the enzymes were mainly involved in carbon metabolism and the biosynthesis of amino acids. Additionally, the relationship between differential abundant enzymes and formation of typical flavour substances in premium and normal BBQ was established. Furthermore, the activities of classic enzymes in BBQ were examined to verify the reliability of metaproteomic results. This study will provide clues to further improve the manufacturing technology for Wuliangye baijiu.     

不同酶制剂的使用有助于皮革质量和面积得率的提高--皮革浸水酶的应用

介绍了浸水酶制剂的使用,从浸水酶的种类、用量,酶对皮革的质量影响,杀菌剂对浸水酶的影响,浸水酶的用法等几个方面进行了论述.     

Enzymes which are stable in the presence of organic solvents

There are numerous advantages of employing enzymes as catalysts in organic solvents or aqueous solutions containing organic solvents instead of water. A few natural enzymes which are stable in the presence of organic solvents have been discovered. However, almost all natural enzymes are easily denatured and inactivated in the presence of organic solvents. Therefore, several physical and chemical methods, such as immobilization, modification, and entrapment, for stabilizing enzymes in the presence of organic solvents were developed. Protein engineering using site directed mutagenesis and directed evolution are useful for clarifying why organic solvent-stable enzymes are stable in the presence of organic solvents and for developing organic solvent-stable mutant enzymes.     

Biofilm − An unrecognised source of spoilage enzymes in dairy products?

Enzymes play an important role in food processing, where they either increase or decrease the value of food commodities. Within the dairy context, undesirable enzymes include indigenous enzymes originating from the cow and microbial enzymes produced by the natural bacteria associated with the cow and its environment. Some of the heat-stable enzymes can remain active after the heat treatments applied during processing and may eventually reduce the quality of the final product. Biofilms may play a role in promoting enzyme production in microorganisms because of the microenvironments created within the biofilm structure. Many studies have been carried out on indigenous and bacterial enzymes that occur in milk, but few studies have looked at the relationship between spoilage enzymes and biofilms. We suggest that bacterial biofilms in dairy manufacture can be a source of dairy spoilage enzymes.     

Quorum-quenching enzymes: Promising bioresources and their opportunities and challenges as alternative bacteriostatic agents in food industry

The problems of spoilage, disease, and biofilm caused by bacterial quorum-sensing (QS) systems have posed a significant challenge to the development of the food industry. Quorum-quenching (QQ) enzymes can block QS by hydrolyzing or modifying the signal molecule, making these enzymes promising new candidates for use as antimicrobials. With many recent studies of QQ enzymes and their potential to target foodborne bacteria, an updated and systematic review is necessary. Thus, the goals of this review were to summarize what is known about the effects of bacterial QS on the food industry; discuss the current understanding of the catalytic mechanisms of QQ enzymes, including lactonase, acylase, and oxidoreductase; and describe strategies for the engineering and evolution of QQ enzymes for practical use. In particular, this review focuses on the latest progress in the application of QQ enzymes in the field of food. Finally, the current challenges limiting the systematic application of QQ enzymes in the food industry are discussed to help guide the future development of these important enzymes.     

酶在南极磷虾高值化利用中的研究进展

近年来,南极磷虾因其巨大的生物储存量以及较高的营养价值越来越受到人们的关注,针对南极磷虾高值化利用的研究也越来越多,其中酶解技术的应用效果显著,弥补了很多传统加工技术的缺陷。本文从酶在南极磷虾蛋白加工中的应用(包括外源酶在南极磷虾蛋白质酶解中的应用、南极磷虾自溶酶的应用),酶在南极磷虾油脂加工中的应用,南极磷虾内源酶的纯化与表征几方面介绍酶在南极磷虾加工中的应用研究进展并对酶在南极磷虾加工的未来发展进行了展望。     

白腐菌Pleurotus eryngii-Co007产木质素降解酶条件的优化

木质素降解酶是参与降解木质素的酶类,广泛存在于白腐真菌中。为提高白腐菌Pleurotus eryngii-Co007的产木质素降解酶的活力,研究了该菌株的产酶曲线、发酵参数及培养基组分对其产木质素降解酶的影响。单因素试验结果表明该菌株发酵第8天时发酵液中木质素降解酶酶活最高;较优的发酵参数是pH 5.0~6.0、发酵温度25~27℃,接种量10%~15%,其中pH影响最显著;麦芽糖和有机氮源有利于木质素降解酶的表达。但考虑到酶表达的增加量和生产成本的经济性选择3%的葡萄糖、0.2%酵母粉和0.2%牛肉膏组合氮源;诱导剂中秸杆、Cu2+和吐温80诱导产酶效果明显。     

采用黑曲霉发酵制备阿拉伯木聚糖酶和阿魏酸酯酶的研究

采用黑曲霉发酵麦麸、蔗渣和玉米麸皮都能获得阿魏酸酯酶和阿拉伯木聚糖酶,并在第3d达到产酶高峰。但不同发酵基质产酶活性差别很大,麦麸最好,蔗渣最差。同时,酶制剂因发酵基质不同会产生底物专一性,因此,在生产酶制剂时应注意根据所降解的对象选择发酵基质。     

Diversity of Glycosyl Hydrolase Enzymes from Metagenome and Their Application in Food Industry

Traditional use of enzymes for food processing and production of food ingredients resulted in fast‐growing enzyme industries world over. The advances in technologies gave rise to exploring newer enzymes and/or modified enzymes for specific application. Search for novel enzymes that can augment catalytic efficiency and advances in molecular biology techniques including sequencing has targeted microbial diversity through metagenomic approaches for sourcing enzymes from difficult to culture organisms. Such mining studies have received more attention in characterizing hydrolases, their prevalence, broad substrate specificities, stability, and independence of cofactors. The focus on glycosyl hydrolases from metagenome for their application in food sector is reviewed.     

生物酶在食品工业中的应用

生物技术是21世纪的高新技术。作为一种高效、安全的生物催化剂,酶已经越来越广泛地应用到食品工业的各个领域中,发挥了其高效、温和、多样及活性可调节的生物学性质,并给传统的食品工业带来了发展新思路。本文综述了酶与食品组织结构和品质的关系、酶在谷物食品加工中的应用以及食品工业中的新酶源,展望了酶工程在食品加工领域中的新进展和应用前景。     

生物膜降解酶对304不锈钢上副溶血弧菌生物膜形成的抑制作用

以副溶血弧菌生物膜基质为靶点,采用96孔板结晶紫染色法筛选出纤维素酶、脂肪酶、蛋白酶k为单酶,将单酶组合为复合酶,在单因素实验的基础上,采用响应面分析法优化组合酶浓度。通过结晶紫染色、菌落计数、扫描电镜等,评价组合酶对304不锈钢上副溶血弧菌生物膜的抑制作用。响应面优化得到的组合酶中纤维素酶浓度为1.00 mg/mL,脂肪酶浓度为1.10 mg/mL,蛋白酶k浓度为1.50μg/mL时生物膜抑制率最大,为89.73%,比优化之前的各单酶相比,对副溶血弧菌生物膜的抑制率有显著性提高,与预测基本相符,说明模型拟合良好,组合酶中各单酶浓度准确可行。优化得到的组合酶有效抑制了304不锈钢上副溶血弧菌生物膜的生长,抑制率为59.35%,扫描电镜图也证实了复合酶的抑制效果。生物膜降解酶复合有效提升了对生物膜的抑制率,为致病菌生物膜的降解及消除提供了新的思路。     

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.     

微生物与酶制剂在秸秆发酵饲料生产中的应用

利用微生物的自身代谢活动与酶制剂而生产的发酵饲料正逐渐成为解决饲料紧张和环境问题的重要手段。微生物与酶制剂将难以直接消化吸收的农作物秸秆等原料转化成易被牲畜采食消化吸收的、营养价值更高且无毒害的发酵饲料。该文对发酵饲料的定义、在发酵饲料中应用的微生物与酶制剂和生产中存在的问题进行了阐述,并对微生物与酶制剂发酵饲料的进一步发展做了展望。     

ENZYME CHANGES IN ROUGH RICE DURING PARBOILING

The enzymes amylase, protease, phosphatase and β-glucosidase in rough rice (paddy) were activated during the soaking step of parboiling. The extent of activation of these enzymes varied with the soaking duration and the parboiling methods adopted. Highest activities were observed in the cold soaking method followed by the double steaming and household methods. β-Glucosidase activity was eliminated in the presteaming stage of the double steaming process. Hot soaking inactivated all these enzymes. The steam in the parboiling process inactivated the enzymes partly while the pressure parboiling process inactivated them totally. Studies with purified enzymes also revealed the activation of enzymes during soaking. Enzyme activity contributes to the loss of solids during soaking and also to the characteristic odor of parboiled rice.     

Enzyme Inactivation in Food Processing using High Pressure Carbon Dioxide Technology

High pressure carbon dioxide (HPCD) is an effective non-thermal processing technique for inactivating deleterious enzymes in liquid and solid food systems. This processing method avoids high temperatures and exerts a minimal impact on the nutritional and sensory properties of foods, but extends shelf life by inhibiting or killing microorganisms and enzymes. Indigenous enzymes in food such as polyphenol oxidase (PPO), pectin methylesterase (PME), and lypoxygenase (LOX) may cause undesirable chemical changes in food attributes, showing the loss in color, texture, and flavor. For more than two decades, HPCD has proved its effectiveness in inactivating these enzymes. The HPCD-induced inactivation of some microbial enzymes responsible for microbial metabolism is also included. This review presents a survey of the published knowledge regarding the use of HPCD for the inactivation of these enzymes, and analyzes the factors controlling the efficiency of HPCD and speculates on the underlying mechanism that leads to enzyme inactivation.     

酶法豆乳工艺的研究

本文研究了蛋白酶和果胶酶在酶法豆乳工艺中的作用机制。采用这两种酶处理大豆不溶性残渣的结果表明,蛋白酶的作用主要是将不溶性的蛋白质转变成可溶性的组分,而果胶酶能部分地降解大豆组织的细胞壁,从而起到增溶大豆不溶性残渣的作用。蛋白酶和果肢酶具有协同作用的效果。酶法豆乳工艺包括了先用蛋白酶后用果胶酶处理的步骤,与传统工艺相比,新工艺显著地提高了原料的利用率和改进了豆乳粉的质量。