酯化红曲（酶）的酯化特性研究

酯化红曲是由红曲菌种和多种产酯功能菌混合培养而成,活性较高,具备良好的专一性。对以烟灰色红曲霉菌种Q-306为出发菌株生产得到的酯化红曲粗酶制剂进行了酯化力验证和酯化特性的研究,结果表明：该酯化红曲对己酸乙酯具有很强的催化专一性,其酯化力为65mg／g．100h,该酯化红曲的最佳催化温度为35℃,最适催化酒精度为20％vol,最适催化pH为3．5,最佳底物浓度为1％。     

红曲霉的生物学特性、酯酶培养技术及质量鉴定

扼要地介绍了红曲霉的生物学特性，红曲霉固体酯酶的培养技术，红曲质量的鉴定及酯酶的酯化力和酯分解率的测定方法。     

烟色红曲霉酯酶特性及在中国酒上的应用

烟色红曲霉(Monacus fulginosus)M-101菌株经麦麸固态培养生成的酯酶,在特定条件下,酯酶活力达14.6U/g,粗酶试验表明:酯酶最适反应温度为50℃,最适反应pH为6.8,耐热性反应在55℃处理1h和45℃处理24h,酶活力基本不变。它可催化合成己酸乙酯,提高酒质。     

红曲霉的生物学特性、酯酶培养技术及质量鉴定

该文扼要地介绍了红曲霉的生物学特性，红曲霉固体酯酶的培养技术，红曲质量的鉴定及酯酶的酯化力和酯分解率的测定方法。     

柑桔属柠檬类果实果胶酯酶的活性分析

果胶酯酶（PE或PME）能催化果胶脱酯生成低酯果胶和果胶酸,属于一类果胶酶,广泛应用于食品特别是果品加工工业中。以新鲜柠檬为原料,采用NaCl-冷冻离心-盐析的方法提取柠檬果实中的果胶酯酶,pH-stat法对果胶酯酶进行活性分析。研究温度、pH、相对储藏度等因素对柠檬类果实果胶酯酶的活性影响,并探索该酶的最适温度、最适pH值,进而研究该酶的热稳定性;对柠檬果实中果胶含量进行测定。实验表明：58℃,pH=6.90时柠檬中的果胶酯酶的活力最高。     

酯化红曲的筛选和酯化酶酶学性质研究

从洋河大曲中筛选到l株具有较高酯化活力的红曲霉,经26S RNA分子鉴定为紫红曲霉(Monascus purpureus),命名为YHM-6.YHM-6菌株能分别耐受8‰的乳酸和10 ％vol的酒精.以YHM-6为出发菌株,生产得到酯化红曲粗酶制剂催化己酸合成己酸乙酯具有很强的专一性和选择性.结果表明,其最适催化温度为35℃,最适催化pH值为3.5,最适催化酒精浓度为28 ％vol,最适己酸浓度为1％,其适合于浓香型白酒和黄水酯化液的生产.     

红曲霉种间产色能力比对与高产色素菌株的筛选

通过筛选高产色素的红曲霉菌株,探讨红曲霉菌株产色素能力以及红曲霉遗传多样性之间的相关性,以期为红曲霉更好的应用奠定基础。对41个红曲霉菌株进行固态发酵法研究其在发酵过程中产色素的能力,并结合ISSR分子标记对红曲霉以及高产色素的红曲霉菌株进行聚类分析。在产色素能力的研究比较中,41个红曲霉中的紫色红曲霉、橙色红曲霉和红色红曲霉相对于丛毛红曲霉、烟灰色红曲霉和白色红曲霉而言,具有更好的产色素能力,且紫色红曲霉相比较橙色红曲霉和红色红曲霉而言,高产红曲色素以及高产各个色素组分的能力更胜一筹,丛毛红曲霉在这6个种中产红曲色素能力最差,同种内的不同菌株产色素能力也差异显著。聚类分析结果显示,红曲霉的亲缘关系与其地理来源有一定的相关性,但种内聚类分析则显示高产色素的红曲霉菌株并不一定聚在一起。     

清香型小曲白酒生产中红曲霉的分离及发酵特性研究

研究采用培养组学首次从清香型小曲白酒绿衣观音土曲和酒醅中分离出9株红曲霉,经形态学和分子生物学分析鉴定为7株紫色红曲霉和2株红色红曲霉。进一步通过耐受性实验发现,该批红曲霉最适pH值为4～5,最低可耐受p H值为3,最高可耐受乙醇浓度为25%vol,以及最适温度为30～35℃。同时,对9株红曲霉制成的红曲米糖化酶活、蛋白酶活和酯化力进行了检测,结果发现红曲T4蛋白酶活最高,红曲M2糖化酶活最高,红曲T2的酯化力最高。本研究阐明了清香型小曲白酒生产中红曲霉种类及发酵特性信息,为下步红曲霉的应用提供了理论依据。     

约氏乳酸杆菌中一种新的阿魏酸酯酶基因的克隆表达与性质研究

阿魏酸是一种重要的抗氧化剂,是近几年研究的热点。阿魏酸酯酶(FAEs)能够水解酯键来释放游离的阿魏酸。本文作者根据约氏乳酸杆菌(Lactobacillus johnsonii)的全基因组序列和阿魏酸酯酶保守序列设计了一个新的阿魏酸酯酶的编码基因Lj0900。通过PCR扩增,酶切连接,成功构建重组载体,并在大肠杆菌(BL21)中成功表达。对表达的FAEs用镍柱进行纯化,对获得纯酶进行了初步的酶学性质研究,用阿魏酸甲酯为底物的情况下,发现该酶的最适温度为30℃,最适pH 6。     

传统食品发酵环境宏基因组中酯酶基因的克隆、表达及性质分析

微生物酯酶是一种广泛应用于食品、医药和精细化工等领域的工业化酶。为了丰富酯酶资源,本文通过提取我国传统发酵食品环境样品总基因组DNA,构建宏基因组文库,从中筛选获得一个新的酯酶基因(est_115),该基因全长948 bp,编码316个氨基酸,其蛋白序列同源性分析,表明与来自Pseudomonas lutea的羧酸酯水解酶同源性最高为38%,显示酯酶Est_115属于新的酯酶类。然后构建了est_115基因重组表达载体,在大肠杆菌BL21(DE3)中获得表达,经纯化得到重组酯酶Est_115。酶学性质的分析表明,该重组酯酶Est_115对酰基碳链较短的对硝基苯酚酯具有较高的催化活性,最适作用温度为35℃,最适p H值为7.0,在10%~18%Na Cl条件下,酶蛋白可保持较高的催化活性,具有良好的耐盐性,提示该酶可以应用在高渗透压食品加工中,是一个新型的极具潜力的酯酶。     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status