黄粉虫幼虫蛋白质的提取研究

研究了不同的介质pH值、提取时间、提取温度和加水比例对黄粉虫幼虫蛋白质的可溶出率(提取率)的影响,分析了3种不同pH值提取的蛋白质的氨基酸组成。结果表明,pH值极大地影响着黄粉虫幼虫蛋白质的溶出率,pH值5.8时溶出率最低,此时可能为黄粉虫蛋白的等电点;pH值10.0或高于此值具有较高的溶出率;水与虫之比为10时蛋白质的可溶出率较其它比例为高;其它的因素对幼虫蛋白质的溶出率影响不大。在pH值2.4、5.8和12.1下提取的蛋白质其氨基酸组成不同,提取的黄粉虫蛋白质必需氨基酸占总氨基酸的含量达40％以上。     

菠菜叶蛋白的提取研究

测定不同生长时期内的菠菜叶蛋白含请，以高蛋白含量生长期内的干菠菜叶作为实验材料，研究不同pH值、提取温度、提取时问及料液比对菠菜叶蛋白溶出率的影响。结果表明，pH值9．5、提取温度55℃、提取时间60min、料液比1：35为菠菜叶蛋白的最佳提取条件；pH4．0为菠菜叶蛋白的最佳沉淀pH值。     

中性蛋白酶提取变性脱脂豆粕中蛋白质的研究

变性豆粕是由大豆浸油后，经高温脱溶所得。本文以高温变性脱脂大豆粕为原料，用正交实验法对变性豆粕在蛋白酶作用下的水解特性进行了深入研究。选用国产1398中性蛋白酶为水解酶对变性豆粕进行水解，研究了变性豆粕中蛋白质溶出率随温度、pH值、时间、底物浓度及用酶量的变化规律，找到了水解变性豆粕的最佳实验条件，为生产实践提供了基础数据。该研究结果对其它蛋白原料的水解特性研究也具有参考价值。研究结果表明：1398中性蛋白酶水解高温变性豆粕的最佳条件为：温度45℃，时间3h，底物浓度1.0%,用酶量1600u/g，pH值7．0，在此条件下，变性豆粕中蛋白质可有90．71％水解溶出。     

碱溶酸沉法提取籽粒苋蛋白质的工艺优化

采用单因素试验及响应曲面试验,研究了浸提液pH,温度,浸提时间,料液比对籽粒苋蛋白质提取率的影响,确定了碱溶酸沉法提取籽粒苋蛋白的最佳工艺参数。结果表明影响籽粒苋蛋白质提取率的主次因素依次为:pH>浸提时间>料液比>提取温度。当pH为10,温度为40℃,浸提时间为107 min,料液比为1∶19时,籽粒苋蛋白质的提取率最高,可达71.83%。     

茶渣中蛋白质酶法提取工艺

研究了蛋白酶法提取茶叶加工后茶渣中蛋白质的工艺。结果显示，碱性蛋白酶和复合蛋白酶提取效果较好；碱性蛋白酶法提取的最佳工艺为酶加量49／6、液固比35：1（mL／g）、提取时间4h，提取率可达34．29，6；复合蛋白酶法提取的最佳提取工艺为酶加量39，6、液固比35：1（mL／g）、提取时间4h，提取率可达18．69／6；双酶法提取中，采用先复合蛋白酶，后碱性蛋白酶，提取效果较好，并且碱性蛋白酶占总酶加量比例对提取率的影响较大，当碱性蛋白酶占25％时，提取率达到最大，为42．19，6；双酶法提取的最佳提取工艺为pH8．0，温度60℃，酶加量49，6，提取率可达47．8％。     

豆腐柴中有效成分复合分离提取研究

试验以豆腐柴叶为原料，采用复合分离提取工艺，提取叶中的蛋白质和果胶产品。首先通过不同溶剂提取蛋白质，得到碱溶性蛋白质〉水溶性蛋白质〉醇溶性蛋白质〉盐溶性蛋白质的结论；并对提取蛋白质后的上清液和滤渣进行了提取果胶的最佳条件和参数的确立，进行了萃取果胶时的萃取液种类、pH和盐析果胶时的盐的用量的单因素实验，又以萃取时的温度、pH、时间和料液比四个因素四个水平进行了正交试验，得到如下结论：从豆腐柴叶中复合提取分离蛋白质和果胶的最佳提取工岂条件：以盐溶液作为复合提取剂较为理想，果胶提取分离的最佳条件为萃取温度90℃、溶液pH值4、萃取时间95min、料液比l：45，在此条件下豆腐柴叶果胶的产量为22％，同时可得到0．15％的蛋白质。     

地木耳蛋白质提取工艺及其稳定性的研究

对地木耳蛋白质的提取工艺及稳定性进行了研究，结果证明地木耳蛋白质可以采用水为溶剂的方法提取，提取最佳条件为pH=9，浓度为3％（w／w），温度为40℃-50℃。提取时间控制在1．5h。2h即可达到较好的收率，蛋白质的收率可达75％。随着pH值的下降，地木耳蛋白质的溶解度也随之下降，pH〈6时蛋白质沉淀明显。地木耳蛋白质的热稳定性较好，加热温度、加热时间均对地木耳蛋白质的稳定性有一定的影响。地木耳蛋白质提取物具有较高的营养价值，可更方便地应用于食品加工业，应用前景广阔。     

小米米糠蛋白的等电点分析

采用盐析法对脱脂小米米糠进行蛋白质提取。结果表明,米糠蛋白质的最佳提取条件为柠檬酸钠饱和度80％,pH值4,温度45℃,上清液浓缩倍数4,蛋白质得率达87．52％。分离得到的蛋白采用碱溶酸沉法测小米米糠蛋白的等电点为3．5。     

高速逆流色谱提取分离红曲色素的研究

本文首先对红曲色素的提取方案进行探讨。采用Mathematica 4软件研究溶剂与pH对提取率的影响。发现在乙醇浓度较低时，升高pH有利于色素溶出，而乙醇浓度较高时，降低pH有利于色素溶出。利用高速逆流色谱（HSCCC）对提取得到的色素进行分离，溶剂系统为石油醚／甲醇／乙酸乙酯／水体积，比例为3／6／5／4，流速1．0毫升／分，将一种黄色素与一种紫红色素分离出来。     

巴西菇多糖提取方法研究

本文探讨了巴西菇多糖的提取工艺，分别作了热水提取和酶法提取的正交试验，并对多糖提取率进行了比较分析。结果显示．热水提取巴西菇多糖的最佳工艺参数是：提取温度110℃，提取时间1．5h，料液比1：25，其多糖最高提取率5．80％。而采用酶法提取巴西菇多糖的最佳工艺参数分别是：木瓜蛋白酶酶用量0．20％，酶解温度55℃，酶解时间2h，作用pH值6．5；纤维素酶酶用量O．15％，酶解温度45℃，酶解时间3h，作用pH值4．5；果胶酶酶用量O．20％，酶解温度40℃，酶解时间3h，作用pH值4．0。其中木瓜蛋白酶提取巴西菇多糖提取率最高，可达到15．08％。     

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