D-阿洛酮糖合成及偶联酿酒酵母发酵的研究

该研究利用含有组成型启动子的质粒pET-20b载体,在大肠杆菌（Escherichia coli）BL21（DE3）中对3种D-阿洛酮糖3-差向异构酶进行异源表达,其后以D-果糖为底物进行静息细胞转化。结果表明,重组菌在摇床30 ℃、200 r/min转速下发酵48 h,能够利用D-果糖为底物生产D-阿洛酮糖,转化率分别达到27.56%、23.99%和25.98%。为降低D-果糖对D-阿洛酮糖纯化过程中的影响,在产糖的过程后偶联酿酒酵母（Saccharomyces cerevisiae）好氧发酵过程,消耗掉混合糖液中的D-果糖,结果显示转化24 h后D-果糖去除率达到94.22%,该研究为下游D-阿洛酮糖的分离和纯化提供了新的思路。     

3种天然甜味剂的风味、生理功能及应用研究进展

大量研究数据表明肥胖、糖尿病和心脑血管疾病的发生与日常糖分摄入过多相关密切。因此,近年来高糖饮食引发的健康风险获得了各国政府与公众的极大关注,国际消费市场对传统甜味剂蔗糖替代品的需求急剧增长。由于消费者对化学合成甜味剂的安全性一直有所顾虑,甜度高、热量低、风味佳、兼具多重功能特性的天然甜味剂成为代糖产品开发研究的热点。目前已有部分口感与蔗糖接近的天然甜味剂产品实现了工业生产并应用于食品加工,在甜味剂行业展现广阔的市场前景。本研究主要针对应用潜力巨大的3种天然甜味剂甜菊糖苷、罗汉果甜苷与D-阿洛酮糖的风味、功能及在食品中的应用进行概述,为甜菊糖苷与罗汉果甜苷的风味改良以及D-阿洛酮糖的安全性评估等工作开展提供借鉴,以期促进天然甜味剂的食品应用深入研究。     

D-阿洛酮糖3-差向异构酶在大肠杆菌内的高效可溶性表达及发酵条件研究

将来源于Clostridium bolteae ATCCBAA-613的DAEase基因序列经密码子优化合成,以pCold TF为表达载体,冷休克启动子CspA低温诱导DAEase基因在大肠杆菌（Escherichia coli）BL21 （DE3）中表达,得到高效可溶性的重组Cb-DAEase并利用镍柱亲和层析分离纯化。结果表明,Cb-DAEase最适pH和温度为7.0和55 ℃,Co2+能够显著（P<0.05）增强酶活力。对培养条件进行优化得到,在7 g/L甘油、10 g/L酵母膏、1%接种量、0.25 mmol/LIPTG、诱导前培养5 h的条件下,Cb-DAEase活力达到（10.11±0.02）U/g,比优化前(1.38±0.01) U/g提高了7.33倍;以120 g/L的D-果糖为底物全细胞催化0.5 h后,D-阿洛酮糖产量为（11.47±0.04）g/L,比优化前（1.03±0.02）g/L提高了11.14倍。基于冷休克表达策略构建的重组菌经发酵优化后Cb-DAEase活力显著（P<0.05）提高,为高效制备D-阿洛酮糖提供了理论支持。     

D-Allose,a Stereoisomer of D-Glucose,Extends the Lifespan of Caenorhabditis elegans via Sirtuin and Insulin Signaling

D-Allose (D-All), C-3 epimer of D-glucose, is a rare sugar known to suppress reactive oxygen species generation and prevent hypertension. We previously reported that D-allulose, a structural isomer of D-All, prolongs the lifespan of the nematode Caenorhabditis elegans. Thus, D-All was predicted to affect longevity. In this study, we provide the first empirical evidence that D-All extends the lifespan of C. elegans. Lifespan assays revealed that a lifespan extension was induced by 28 mM D-All. In particular, a lifespan extension of 23.8 % was achieved (p < 0.0001). We further revealed that the effects of D-All on lifespan were dependent on the insulin gene daf-16 and the longevity gene sir-2.1, indicating a distinct mechanism from those of other hexoses, such as D-allulose, with previously reported antiaging effects.     

Recent Research and Progress in Food,Feed and Nutrition with Advanced Synchrotron-based SR-IMS and DRIFT Molecular Spectroscopy

Ultraspatially resolved synchrotron radiation based infrared microspectroscopy is able to detect the structure features of a food or feed tissue at cellular and molecular levels. However, to date, this advanced synchrotron-based technique is almost unknown to food and feed scientists. The objective of this article was to introduce this novel analytical technology, ultra-spatially resolved synchrotron radiation based infrared microspectroscopy (SR-IMS) to food, feed, conventional nutrition, and molecular nutrition scientists. The emphasis of this review focused on the following areas: (1) Principles of molecular spectroscopy for food and feed structure research, such as protein molecular structure, carbohydrate conformation, heating induced protein structure changes, and effect of gene-transformation on food and feed structure; (2) Molecular spectral analysis methodology; (3) Biological applications of synchrotron SR-IMS and DRIFT spectroscopy; and (4) Recent progress in food, feed and nutrition research program. The information described in this article gives better insight in food structure research progress and update.     

Direct production of allitol from D-fructose by a coupling reaction using D-tagatose 3-epimerase, ribitol dehydrogenase and formate dehydrogenase

Allitol was produced from D-fructose via a new NADH-regenerating enzymatic reaction system using D-tagatose 3-epimerase (D-TE), ribitol dehydrogenase (RDH), and formate dehydrogenase (FDH). D-fructose was epimerized to D-psicose by the D-TE of Pseudomonas cichorii ST-24 and the D-psicose was subsequently reduced to allitol by the RDH of an RDH-constitutive mutant, X-22, derived from Klebsiella pneumoniae IFO 3321. NADH regeneration for the reduction of D-psicose by the RDH was achieved by the irreversible formate dehydrogenase reaction, which allowed the D-psicose produced from d-fructose to be successively transformed to allitol with a production yield from D-fructose of almost 100%. The reactions progressed without any by-product formation. After separation of the product from the reaction mixture by a simple procedure, a crystal of allitol was obtained in a yield exceeding 90%. This crystal was characterized and determined to be allitol by HPLC analysis, its IR and NMR spectra, its melting point, and optical rotation measurement.     

Characteristics and antioxidant activity of Maillard reaction products from psicose-lysine and fructose-lysine model systems

D-Psicose, an epimer of D-fructose isomerized at C-3 position, is a rare ketohexose that is thought to be beneficial for obese people and diabetic patients as a noncaloric sweetener. In the present study, model Maillard reaction products were obtained from D-psicose (or D-fructose) and L-lysine heating at 120 °C up to 8 h with the initial pH 9.0. The changes in pH, UV-vis absorbance, and free amino groups during the reaction were detected. Moreover, the antioxidant potential of the Maillard reaction products at different intervals was investigated. Although there was almost no difference in the oxygen radical absorbance capacity, the Maillard reaction products from psicose performed better than that from fructose in the radical-scavenging activity of 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and 1, 1,-diphenyl-2-picryl-hydrazyl. The reducing power of the Maillard reaction products from psicose was also stronger than that from fructose. These results indicated that psicose played an effective role in the Maillard reaction and its Maillard reaction products could act as potential antioxidants in food industry.     

噬菌体在食品安全控制中的研究进展

近年来,噬菌体在食品科学领域中的应用受到国内外研究学者的广泛关注。噬菌体的自身特性表明,其可 作为一种杀菌/抑菌的生物制剂来控制食源性病原菌对食品的污染,是保障食品安全的理想工具。此外,基因工程 技术的发展进一步促进了噬菌体及其产物的安全、高效使用及噬菌体产品的出现。本文就噬菌体在食品安全控制中 的研究进展以及应用前景等方面进行综述。     

CRISPR/Cas9介导的果糖低消耗酿酒酵母工程菌的构建

利用酿酒酵母为宿主,以果糖为原料合成D-阿洛酮糖具有食品方面的先天优势。为了减少酿酒酵母宿主本身对果糖的消耗,对酿酒酵母的己糖激酶同工酶2(Hexokinaseisoenzyme2,hxk2)基因进行编辑。本研究采用CRISPR/Cas9技术,构建了Cas9和gRNA共表达质粒p YES2-CG-Δhxk2,以酿酒酵母BY4741为出发菌株,URA3为筛选标记,采用高效电击转化法和胞内同源重组技术,获得hxk2基因缺陷株BY4741-Δhxk2。在此基础上,进行果糖发酵实验以评估突变菌株的果糖消耗速率。实验结果显示,发酵培养14 h时,缺陷株BY4741-Δhxk2果糖消耗速率为3.35 mg/h;与野生型菌株相比其下降了6.42%。此外,发酵培养22 h,BY4741-Δhxk2的OD600nm值为8.65,相比于野生型提高了6.40%。研究表明,己糖激酶hxk2基因的缺陷编辑可以一定程度降低酿酒酵母对果糖的利用,同时缺陷株较野生型表现出一定的生长优势,这为后续以酿酒酵母为宿主生产D-阿洛酮糖奠定了初步基础。     

Food Safety Evaluation Based on Near Infrared Spectroscopy and Imaging: A Review

In recent years, due to the increasing consciousness of food safety and human health, much progress has been made in developing rapid and nondestructive techniques for the evaluation of food hazards, food authentication, and traceability. Near infrared (NIR) spectroscopy and imaging techniques have gained wide acceptance in many fields because of their advantages over other analytical techniques. Following a brief introduction of NIR spectroscopy and imaging basics, this review mainly focuses on recent NIR spectroscopy and imaging applications for food safety evaluation, including (1) chemical hazards detection; (2) microbiological hazards detection; (3) physical hazards detection; (4) new technology-induced food safety concerns; and (5) food traceability. The review shows NIR spectroscopy and imaging to be effective tools that will play indispensable roles for food safety evaluation. In addition, on-line/real-time applications of these techniques promise to be a huge growth field in the near future.     

Recent research in flaxseed (oil seed) on molecular structure and metabolic characteristics of protein,heat processing-induced effect and nutrition with advanced synchrotron-based molecular techniques

Advanced synchrotron radiation-based infrared microspectroscopy is able to reveal feed and food structure feature at cellular and molecular levels and simultaneously provides composition, structure, environment, and chemistry within intact tissue. However, to date, this advanced synchrotron-based technique is still seldom known to food and feed scientists. This article aims to provide detailed background for flaxseed (oil seed) protein research and then review recent progress and development in flaxseed research in ruminant nutrition in the areas of (1) dietary inclusion of flaxseed in rations; (2) heat processing effect; (3) assessing dietary protein; (4) synchrotron-based Fourier transform infrared microspectroscopy as a tool of nutritive evaluation within cellular and subcellular dimensions; (5) recent synchrotron applications in flaxseed research on a molecular basis. The information described in this paper gives better insight in flaxseed research progress and update.     

小球藻的营养保健功能及其在食品工业中的应用

小球藻是一种高蛋白、高多糖、低脂肪、富含多种维生素及矿物质的单细胞藻类,具有多种保健功能,可作为功能食品和营养强化剂应用于食品工业。本文综述了小球藻在食品领域开发利用的进展,着重从小球藻的营养价值、保健功能以及其在食品工业中的具体应用3 方面进行阐述。     

角蛋白酶的来源、理化性质与生物工程研究进展

角蛋白酶由微生物产生,可特异性降解羽毛等含角蛋白类的物质,在食品、医药和饲料生产上具有潜在的应用价值。文中概述了不同来源的角蛋白酶及其性质;介绍了角蛋白酶的生物工程研究新进展;对角蛋白酶生产应用途径进行了探讨。     

食品用萜类化合物的生物合成研究进展

萜类化合物在食品中有重要的应用,可用作香精香料、甜味剂、营养强化剂等,作为一类天然添加剂而受到人们的青睐。生物 合成法作为萜类化合物合成中最具发展潜力的方法而备受关注。 该文从萜类化合物在食品中的应用,萜类化合物生物合成途径,微 生物合成萜类化合物的研究进展三方面进行介绍,旨在为生物合成食品用萜类化合物的研究提供参考。     

Recent advances on protein‐based Pickering high internal phase emulsions (Pickering HIPEs): Fabrication,characterization, and applications

Most trans fats in processed foods come from partially hydrogenated oils (PHOs). Numerous studies have shown that the excessive intake of trans fats may cause some adverse effects on human health. An effective alternative to PHOs is to construct Pickering high internal phase emulsions (HIPEs). In recent years, considerable attention has been paid to Pickering HIPEs stabilized by protein‐based particles because of their high stability and promising applications in the fields of food, cosmetics, and pharmaceutical industries. This review summarizes the recent progress of Pickering HIPEs stabilized by protein‐based particles focusing on the methods for their preparation and characterization, and discusses the applications of Pickering HIPEs in the food industry. Promising research trends in this field are also proposed, including (a) developing protein‐based antioxidant Pickering HIPEs and Pickering nanoemulsions, and (b) expanding the potential applications of protein‐based Pickering HIPEs in the fields of delivery vehicles, the template for porous materials, and biodegradable packaging films. This review will provide a theoretical basis for future technological innovation and application development of protein‐based Pickering HIPEs.     

4D打印技术在食品加工领域的研究进展

4D打印技术作为3D打印技术的延伸,可以促使打印材料的结构、形状以及功能随时间的变化而发生改变,从而实现打印材料由静态结构向动态结构的转变。4D打印技术作为新兴的数字化生产技术,其早期主要应用于医学和工业领域。近几年,4D打印技术逐渐在食品领域得到了一定的应用。通过4D打印可以设计并生产出营养价值更高、感官品质更佳的新型食品。本文综述4D打印食品技术的原理、影响因素以及打印设备,并进一步地论述4D打印技术在食品加工领域的国内外研究进展及其优势,最后展望4D打印食品技术的发展前景,以期为4D打印技术在食品领域的应用研究提供参考。     

Trace analysis of organic compounds in foods with surface‐enhanced Raman spectroscopy: Methodology,progress, and challenges

Surface‐enhanced Raman spectroscopy (SERS) provides a potential solution for rapid analysis of trace compounds such as residual pesticides, naturally occurred toxicants, banned or restricted drugs, and food additives in complex food matrices. In this review, the basic principles of SERS and general approaches to successfully apply SERS in food analysis are covered from an applications perspective. The key steps including substrate selection and evaluation, sample preparation and simplification, spectral collection, and data analysis during the development of SERS methods for food analysis are summarized, together with the discussion of typical underlying technical barriers or major challenges of these methods and their applications. Future directions in successfully applying SERS technology as a routine analytical approach to solve real‐world food problems are analyzed. This comprehensive review summarizes the recent progress on theory, application, and scope of SERS for food analysis, providing a basic understanding of the technology; more importantly, key methodology, potential pitfalls, and possible solutions during the development of rapid SERS methods based on authors’ years of SERS experience are shared with researchers in the field.     

Mass production of D-psicose from d-fructose by a continuous bioreactor system using immobilized D-tagatose 3-epimerase

An improved process for the mass production of D-psicose from D-fructose was developed. A D-fructose solution (60%, pH 7.0) was passed at 45 degrees C through a column filled with immobilized D-tagatose 3-epimerase (D-TE) which was produced using recombinant Escherichia coli, and 25% of the substrate was converted to D-psicose. After epimerization, the substrate, D-fructose, was removed by treatment with baker's yeast. The supernatant was concentrated to a syrup by evaporation under vacuum and D-psicose was crystallized with ethanol. Approximately 20 kg of pure crystal D-psicose was obtained in 60 d.     

酪蛋白糖巨肽的生物学活性

酪蛋白糖巨肽(Caseino Glycomacropeptide,简称CGMP)主要是κ-酪蛋白经凝乳酶降解产生的一类含有糖链的多肽,具有许多的生理活性功能和独特的营养特性,可广泛地应用于保健食品和医药品.综述了CGMP的一些生理功能研究进展以及其生产制备工艺的现状,同时也介绍了它在食品和医药品中的应用前景.     

Pediocin PA-1, a wide-spectrum bacteriocin from lactic acid bacteria

Pediocin PA-1 is a broad-spectrum lactic acid bacteria bacteriocin that shows a particularly strong activity against Listeria monocytogenes, a foodborne pathogen of special concern among the food industries. This antimicrobial peptide is the most extensively studied class Ila (or pediocin family) bacteriocin, and it has been sufficiently well characterized to be used as a food biopreservative. This review focuses on the progress that have been made in the elucidation of its structure, mode of action, and biosynthesis, and includes an overview of its applications in food systems. The aspects that need further research are also addressed. In the future, protein engineering, genetic engineering and/or chemical synthesis may lead to the development of new antimicrobial peptides with improved properties, based on some features of the pediocin PA-1 molecule.