Recent advances in biotechnological valorization of brewers' spent grain

Brewers'' spent grain (BSG) is the most abundant by-product of beer-brewing. BSG is rich in nutrients such as protein, fiber, minerals, and vitamins, and therefore it is conventionally used as low-cost animal feed. On the other hand, alternative utilization of BSG has gained increased attention during recent years due to technological progress in its processing and the emergence of the concept of circular economy. The valorization of BSG through biotechnological approaches is environmentally friendly and sustainable. This review was focused on recent advancements in the conversion of BSG into value-added products, including bioenergy (ethanol, butanol, hydrogen, biodiesel, and biogas), organic acids, enzymes, xylitol, oligosaccharides, and single cell protein, via biotechnological approaches. In addition, the potential applications of BSG as immobilization matrices in bioprocesses have been reviewed.     

Microencapsulation of Oils: A Comprehensive Review of Benefits,Techniques, and Applications

Microencapsulation is a process of building a functional barrier between the core and wall material to avoid chemical and physical reactions and to maintain the biological, functional, and physicochemical properties of core materials. Microencapsulation of marine, vegetable, and essential oils has been conducted and commercialized by employing different methods including emulsification, spray‐drying, coaxial electrospray system, freeze‐drying, coacervation, in situ polymerization, melt‐extrusion, supercritical fluid technology, and fluidized‐bed‐coating. Spray‐drying and coacervation are the most commonly used techniques for the microencapsulation of oils. The choice of an appropriate microencapsulation technique and wall material depends upon the end use of the product and the processing conditions involved. Microencapsulation has the ability to enhance the oxidative stability, thermostability, shelf‐life, and biological activity of oils. In addition, it can also be helpful in controlling the volatility and release properties of essential oils. Microencapsulated marine, vegetable, and essential oils have found broad applications in various fields. This review describes the recognized benefits and functional properties of various oils, microencapsulation techniques, and application of encapsulated oils in various food, pharmaceutical, and even textile products. Moreover, this review may provide information to researchers working in the field of food, pharmacy, agronomy, engineering, and nutrition who are interested in microencapsulation of oils.     

乳酸克鲁维酵母作为微生物细胞工厂的应用研究进展

乳酸克鲁维酵母（Kluyveromyces lactis）是一种典型的非常规酵母,在微生物基础研究和应用研究方面都有着非常重要的用途。该酵母具有食品安全级别高、蛋白分泌能力强、整合表达能力高效及大规模发酵能力优异等特点,因此,工业应用前景较为广阔。目前,乳酸克鲁维酵母作为蛋白表达系统已在食品和医药等行业中得到了广泛应用。近年来,国内外生物技术领域的科研人员以乳酸克鲁维酵母作为底盘细胞,利用合成生物学技术已经成功构建出了能够生产各种生化产品的微生物细胞工厂,该技术展示出了极大的发展潜力。本文主要对乳酸克鲁维酵母的菌种特点、合成生物学元件、遗传操作工具、基因编辑策略进行介绍,并综述乳酸克鲁维酵母作为细胞工厂的应用研究进展,可以为今后利用合成生物学方法在乳酸克鲁维酵母底盘中构建生产各种高附加值产品的高效微生物细胞工厂提供理论指导。     

Microbial Biosensors for Environmental Monitoring and Food Analysis

A microbial biosensor is an elaborate analytic device that uses microorganisms as recognition elements, mainly for application in environmental monitoring, food safety, military defense, and medicine. The selection and immobilization of microorganisms are key steps that must first be addressed for microbial biosensors. Currently, genetically modified microorganisms play an increasingly significant role in improving the capacity of biosensors. Electrochemical and optical types of transducers have been widely employed in microbial biosensors, although bioluminescence and fluorescence methods have been highlighted recently. Additionally, the microbial fuel cell (MFC), which has been mainly applied in biological oxygen demand (BOD) biosensors, is a promising technology. This article reviews recent developments of microbial biosensors with respect to their applications in environmental monitoring and food analysis, including measurement of a variety of common pollutants, products in fermenting processes, antibiotic residues, and toxins in food. Current limitations and prospective future directions, such as performance optimization, developing portable biosensors for on-site monitoring, combination of genetic and DNA approaches, nanotechnology, and phage-based biosensors for foodborne pathogens, are also discussed in this review.     

Protective approaches and mechanisms of microencapsulation to the survival of probiotic bacteria during processing,storage and gastrointestinal digestion: A review

Abstract

In recent years, there is a rising interest in the number of food products containing probiotic bacteria with favorable health benefit effects. However, the viability of probiotic bacteria is always questionable when they exposure to the harsh environment during processing, storage, and gastrointestinal digestion. To overcome these problems, microencapsulation of cells is currently receiving considerable attention and has obtained valuable effects. According to the drying temperature, the commonly used technologies can be divided into two patterns: high temperature drying (spray drying and fluid bed drying) and low temperature drying (ultrasonic vacuum spray drying, spray chilling, electrospinning, supercritical technique, freeze drying, extrusion, emulsion, enzyme gelation, and impinging aerosol technique). Furthermore, not only should the probiotic bacteria maintain high viability during processing but they also need to keep alive during storage and gastrointestinal digestion, where they additionally suffer from water, oxygen, heat as well as strong acid and bile conditions. This review focuses on demonstrating the effects of different microencapsulation techniques on the survival of bacteria during processing as well as protective approaches and mechanisms to the encapsulated probiotic bacteria during storage and gastrointestinal digestion that currently reported in the literature.     

Microencapsulation of probiotic cells for food applications

The addition of microencapsulated probiotic cells to food products is a relatively new functional food concept. Most of the published scientific research in this field is not older than ten years. However, the technological background reaches back to the 1980s, where lactic acid bacteria were microencapsulated within the concept of the so-called immobilized cell technology (ICT). Target applications of ICT were continuous fermentation processes and improved biomass production. The methods adopted from immobilized cell technology were applied for the microencapsulation of probiotics, often optimized towards specific requirements associated with the protection of probiotic cells in food applications. However, there are still significant hurdles with respect to currently available methods for probiotic cell microencapsulation. This is mainly due to the fact that important characteristics of microcapsules based on ICT appear to be in conflict with the requirements arising from an application of probiotic microcapsules in food products, with particle size and inappropriate matrix characteristics being the most prominent ones. Based on this situation the aim of this review is to give a critical overview of the current approaches regarding the microencapsulation of probiotic cells for food applications and to report on emerging developments.     

内酯类香料的微生物法转化制备及其调控研究进展

内酯类香料因具有典型奶香和花果香气,被广泛地应用于糖果、饮料、乳制品、烘焙等食品中。得益于近些年来消费者对于产品天然特性的喜爱,内酯类香料的微生物法转化制备备受关注。本文综述了γ-和δ-两类内酯的微生物法转化机理包括脂肪酸进入线粒体方式、β-氧化、环化过程和降解代谢途径。对目前已有的生物转化法调控方式如基于基因组学的基因调控、溶氧氧合、底物分批培养、细胞固定化、菌种诱变等进行了总结,展望了内酯类香料的调控研究方向,为更经济高效的生物法转化内酯类香料提供借鉴。     

Microenvironment of alginate-based microcapsules for cell culture and tissue engineering

As a type of 3D model, the technology of microencapsulation holds significant promise for tissue engineering and cell therapy due to its unique performance. The microenvironmental factors within microcapsules play an important role in influencing the behaviors of encapsulated cells. The aim of this review article is to give an overview on the construction of the microenvironmental factors, which include 3D space, physicochemical properties of alginate matrix, cell spheroids, nutritional status, and so on. Furthermore, we clarified the effect of microenvironmental factors on the behaviors of encapsulated cells and the methods about improving the microenvironment of microcapsules. This review will help to understand the interaction of the microenvironment and the encapsulated cells and lay a solid foundation for microcapsule-based cell therapy and tissue engineering.     

Microencapsulation of bacteria: A review of different technologies and their impact on the probiotic effects

Probiotic based products are associated with many health benefits. However, the main problem is the low survival of these microorganisms in food products and in gastrointestinal tract. Providing probiotics with a physical barrier is an efficient approach to protect microorganisms and to deliver them into the gut. In our opinion, microencapsulation is one of the most efficient methods, and has been under especial consideration and investigation. However, there are still many challenges to overcome with respect to the microencapsulation process. This review focuses mainly on the methodological approach of probiotic encapsulation including materials and results obtained using encapsulated probiotic in food matrices and different pathologies in animal models.Industrial relevanceThe inclusion of probiotics into food matrices is one of the most challenging lines of research in food technology. Probiotics in general, and some strains in particular, have a low resistance to different environmental conditions, such as oxygen, light or temperature. Thus, the protection and isolation of the microorganism from the food matrix and the environmental condition are crucial for the development of new probiotic food. In this sense, microencapsulation has gained an increasing interest, since it has been demonstrated that it could protect the bacteria not only during its production process but also during its incorporation into the food matrix, also with protective effects during storage. In conclusion, microencapsulation is of great interest since it could allow a wider application of probiotics in the food market, actually restricted to fresh or powder products.     

解脂耶氏酵母作为微生物细胞工厂的应用研究进展

解脂耶氏酵母（Yarrowia lipolytica）是一种重要的工业微生物菌种，被公认为食品级安全微生物。近年来，随着合成生物学和基因编辑技术的快速发展，科学家们利用合成生物学及基因编辑技术已经成功构建出了能够生产生物化学品、生物燃料、香料、药物、工业酶和药用蛋白等多种高附加值工业产品的解脂耶氏酵母细胞工厂，使得该酵母在食品、药品和生化能源等领域均具有巨大的应用潜力。本文将重点介绍解脂耶氏酵母表达系统、合成生物学元件和基因编辑方法的最新研究进展和应用情况，并对近年来以解脂耶氏酵母作为微生物细胞工厂生产高附加值产品的应用实例进行总结，希望为研究人员进一步利用解脂耶氏酵母进行底盘细胞设计、构建和优化相关合成途径并最终实现目的产物的高效合成提供有用的信息。     

Uses of biotechnology and technology transfer to keep food safe

The era of biology is composed of 1) the definition of molecular laws of biology, 2) the exponential expansion of the data base, and 3) the establishment of the first generation molecular and cellular tool kit; this era is driving the development and commercialization of biotechnological products and processes for agriculture and the food system. These products and processes should have a major impact in maintaining and improving food safety. Several meeting and organizational initiatives on biotechnology and food safety are summarized. Possible roles of biotechnology in areas of food safety involve microbial contaminants, nutritional quality, natural antimetabolites, allergens, toxicants, and synthetic chemical residues. Biotechnology will have an impact on all these areas through both improved ability to measure as well as to modify microbes, animals, and plants used as food. Diagnostics for microbial contaminants and biobased alternatives to synthetic chemicals are most advanced. However, all these biotechnological products and processes for food safety are in very early stages of development and commercialization.     

磁性微球研究进展及其在固定化酶中的应用

磁性高分子微球是最近发展起来的一种新型功能高分子材料,它作为酶、细胞、药物等的载体被广泛地应用到了生物工程、细胞学和生物医学等领域.本文对磁性高分子微球的研究现状进行了综述,介绍了磁性微球的制备、性质,重点讨论了其用于酶的固定化研究,各种固定化酶的方法并指出了该领域今后的研究方向.     

Protecting probiotic bacteria by microencapsulation: challenges for industrial applications

The use of probiotic bacteria in novel foods to provide beneficial health effects is today of increasing interest in the food industry. The process stability of probiotics is, however, not always optimal. Microencapsulation technology can be used to maintain the viability of probiotic bacteria during food product processing and storage. Both true microcapsules with coating as well as microspheres where the bacteria are evenly spread in the coating material are discussed. It is important that encapsulation keeps the probiotics active through the gastrointestinal tract and releases them in their target organ. The survival of microencapsulated cells in simulated gastric conditions is therefore also reviewed. Polysaccharides like alginate, gellan, κ-carrageenan and starch are the most commonly used materials in microencapsulation of bifidobacteria and lactobacilli. Techniques commonly applied for probiotic microencapsulation are emulsion, extrusion, spray drying, and adhesion to starch. Bead stability can be improved by using different coating materials, e.g. chitosan. Future challenges in the field include recognition of new potent applications, selection of appropriate techniques, materials and bacterial strains, and minimizing the extra costs incurred by microencapsulation.     

香兰素的生物合成

简介了香兰素的应用、生产现状。概述了近年来利用发酵工程、酶工程以及细胞工程等生物技术生产香兰素的方法。最后简单比较了各种方法生产香兰素的经济性、安全性 ,认为生物技术 ,特别是发酵工程将广泛用于香兰素的生产     

喷雾干燥法制取宝石鱼油微胶囊技术研究(Ⅰ)

以宝石鱼油微胶囊制品包埋率作为主要评价指标,筛选出喷雾干燥法制取宝石鱼油微胶囊壁材配方组成;通过对五组壁材配方喷雾效果及微胶囊制品特性比较,得出宝石鱼油微胶囊壁材配方组成为:变性淀粉46．75％、酪蛋白酸钠2％、鱼油20％。     

发酵肉制品加工中衍生的非健康因子控制研究进展

通过微生物发酵的方法,开发肉制品新种类,来达到改善肉品的营养价值,增加风味的目的。然而,由于发酵体系中的不良微生物或发酵原料本身都有可能导致发酵食品中存在一些非健康因子,进而危害人体健康。本文对发酵肉制品加工中衍生的醛类、多环芳烃等内源非健康因子,以及生物胺、亚硝胺等与微生物相关的外源非健康因子的形成机制及其危害进行论述,并从传统方法和生物技术手段两个层面阐述控制非健康因子产生的主要策略,旨在对发酵肉制品产业化生产中,有效降低非健康因子危害,提高食品安全性,为促进发酵肉制品产业健康发展提供参考。     

肉及肉制品微生物检测新技术研究进展

肉及肉制品营养丰富,也易受微生物污染,其食用安全性备受关注。本文介绍肉及肉制品中微生物限量要求,分析传统微生物检测方法的弊端,综述快速测试片法、三磷酸腺苷生物荧光法、分子诊断法、免疫分析法、光谱法、仪器法等新技术在肉及肉制品中微生物检测应用中的研究进展,以期为国内学者开展相关研究提供参考,满足肉类产业对微生物检测快速、准确的需求,为肉类企业减轻流通压力并降低由此带来的经济损失。     

木聚糖水解酶的研究进展

木聚糖水解酶是一种复杂的复合酶系统，广泛分布于自然界的细菌和真菌中，将木聚糖水解酶用于食品工业、家禽饲料工业及纸浆漂白，已被认为是这种酶生物工程技术应用的一个最重要方面。在工业技术中要成功的应用木聚糖酶，了解酶的合成与作用机制是必不可少的。本文全面地介绍木聚糖酶的特性、作用机制、诱导合成、高产菌株筛选等新近的研究进展。     

Stability of Lactobacillus reuteri in Different Types of Microcapsules

This study was designed to find the most suitable method and wall material for microencapsulation of the probiotic bacterium Lactobacillus reuteri to maintain cell viability during gastric challenge. Five L. reuteri strains were individually encapsulated using alginate, alginate plus starch, K‐carrageenan with locust bean gum, or xanthan with gellan by extrusion or phase separation (emulsion). The morphology of the microcapsules was studied using phase contrast and cryo‐scanning electron microscopy (cryo‐SEM). The resistance of these microcapsules and the viability of contained L. reuteri to simulated gastric juice were studied. The shape and size of the microcapsules produced varied with the preparation method and type of wall material. Extruded microcapsules were larger and more uniformly shaped. Survival of microencapsulated L. reuteri was significantly better than that of planktonic cells and varied with the strain, method of microencapsulation, and wall material used. In general, microencapsulation using alginate and alginate with starch by both extrusion and phase separation were found to provide bacteria significantly greater protection (P < 0.05) against simulated gastric juice.