AOT/正己烷反胶束体系酶催化合成己酸乙酯研究

该研究以脂肪酶为催化剂,在AOT/正己烷反胶束体系中催化合成己酸乙酯。此体系最佳反应条件为:反应物浓度0.15 mol/L(己酸)、乙醇与己酸摩尔比1∶1.5、加酶量4 mg、反胶束溶液10 ml、AOT浓度0.05 mol/L、反应温度40℃、缓冲溶液pH=7.5、含水量Wo为12,反应36 h后转化率变化不大,此时转化率约为82.8%;并对合成产物应用红外光谱、GC–MS方法进行表征,结果显示,合成产物为己酸乙酯。     

反胶束法提取红芸豆蛋白的前萃工艺优化

采用二-（2-乙基已基）琥珀酸酯磺酸钠（AOT）-异辛烷-氯化钾组成的反胶束体系萃取红芸豆蛋白（RKBP）。采用电导法考察AOT浓度对AOT-异辛烷-水反胶束体系含水量和临界增溶水量的影响,确定反胶束体系稳定的AOT浓度范围。采用单因素实验分别研究了AOT浓度、缓冲液pH、KCI浓度和萃取时间等因素对RKBP前萃率的影响,通过正交实验优化前萃条件。结果表明,不同AOT浓度对应的反胶束体系的临界含水量值（Wc）基本一致,反胶束体系能够增溶的水的体积随AOT浓度的增加而明显增大,反胶束体系稳定的AOT浓度上限值为2mol／L。正交优化获得反胶束法萃取RKBP的最佳前萃条件为：AOT浓度1．25mol／L,缓冲溶液pH7．5,KCl浓度0．05mol／L,萃取时间90min。在该最优工艺条件下,RKBP前萃率达到43．57％。     

脂肪酸单甘油酯的酶催化合成及其表征

以癸酸甲酯、月桂酸甲酯、肉豆蔻酸甲酯、棕榈酸甲酯和硬脂酸甲酯为原料,与甘油进行脂肪酶催化酯交换反应制备脂肪酸单甘油酯,产物为脂肪酸单甘油酯和少量脂肪酸双甘油酯的混合物,其中脂肪酸单甘油酯的质量分数均在91%以上,最高可达95.9%。随着碳链长度的增加,脂肪酸甲酯的转化率降低,脂肪酸单甘油酯的质量分数也降低。采用气相色谱-质谱联机、核磁共振氢谱和红外光谱,对柱层析分离后的脂肪酸单甘油酯进行了结构表征。     

黏度法对AOT/异辛烷反胶束体系的研究

利用黏度法测定AOT/异辛烷反胶束溶液的黏度,讨论了含水量对反胶束溶液的黏度、水池直径和反胶束聚集数的影响。由此解释了用AOT/异辛烷反胶束溶液萃取大豆蛋白时,萃取率变化的原因。     

木糖醇月桂酸单酯的酶法制备工艺研究

研究了以木糖醇和月桂酸为原料,在固定化脂肪酶Novozym 435的催化下合成木糖醇月桂酸单酯。考察了酸醇摩尔比、脂肪酶添加量、溶剂添加量、分子筛添加量、反应时间、反应温度对反应的影响。结果表明:最佳反应条件为反应溶剂为叔丁醇、酸醇摩尔比1∶2、溶剂添加量20 m L/mmol(以月桂酸物质的量计)、脂肪酶添加量10 g/L、分子筛添加量80 g/L、反应温度85℃、反应时间4 h,在此条件下月桂酸转化率为91.8%。通过红外光谱和质谱进行结构鉴定,产物为木糖醇月桂酸单酯。     

AOT/异辛烷反胶束体系W_0调控及萃取大豆蛋白研究

该文对影响丁二酸二异辛酯磺酸钠(AOT)反胶束体系W0的各因素进行了研究,结果表明:随着加水量的增大,反胶束体系W0增大;而离子强度与AOT浓度增大,反胶束体系W0反而减小。采用AOT反胶束体系萃取大豆蛋白质,可得到最佳前萃取工艺为:缓冲溶液pH 6.5、W015、萃取温度45℃、离子强度0.05 mol/L。     

AOT与SDS复合反胶束体系的研究

研究丁二酸二异辛酯磺酸钠(AOT)与十二烷基硫酸钠(SDS)复合反胶束的体系特征,并与AOT、SDS单一反胶束体系进行对比。结果表明,随着表面活性剂浓度的升高,3种反胶束体系WO逐渐下降,增比黏度逐渐上升,电导率基本没有变化;随着加水量的增加,3种反胶束体系WO、增比黏度以及电导率都逐渐升高。AOT与SDS复合反胶束可以加溶更多的水,且体系较为稳定,这为AOT与SDS复合反胶束体系萃取技术的进一步研究提供了可靠的理论依据。     

反胶束固定木瓜蛋白酶的动力学研究

为了解木瓜蛋白酶在AOT/异辛烷反胶束体系中的催化行为,研究底物浓度、表面活性剂浓度、水含量ω(o)、pH值、温度、盐的浓度及种类对酶活力的影响.在单因素试验基础上,采用响应面法建立二次多项数学模型,并验证该模型的有效性.结果表明:酶作用于反胶束膜,最佳酶活力条件:含水量ω(o)为15,底物质量浓度12mg/mL,KCl浓度0.13 mol/L,温度50℃,pH 4.4,AOT质量浓度0.07 g/mL时,酶活力较高,可达720 431 U/mL.     

复合反胶束萃取花生蛋白的工艺优化

采用AOT(丁二酸二异辛酯磺酸钠)、SDS(十二烷基硫酸钠)/异辛烷—正辛醇复合反胶束体系,超声辅助萃取花生蛋白,研究超声时间、花生浓度、超声功率、pH、离子浓度、温度、W0(反胶束溶液增溶水与表面活性剂摩尔比)、AOT(g)∶SDS(g)、表面活性剂浓度对蛋白萃取率的影响.结果表明,最佳提取工艺为温度35℃、KCl浓度0 mol/L,pH值8,表面活性剂浓度0.08 g/mL,AOT(g)∶SDS(g)为4∶3,超声功率180 W,W0值15,该工艺条件下,花生蛋白的萃取率为93.33％.     

两种反胶束体系对大豆蛋白前萃的比较研究

主要研究了以SDS/异辛烷/正辛醇反胶束体系萃取大豆蛋白的前萃过程,并分析了各因素对蛋白前萃率的影响,与AOT/异辛烷反胶束体系萃取大豆蛋白进行比较,SDS/异辛烷/正辛醇反胶束体系提取大豆蛋白的前萃率高于AOT/异辛烷反胶束体系。SDS/异辛烷/正辛醇反胶束体系萃取低温脱溶豆粕中蛋白质的最佳前萃工艺条件为:SDS浓度0.08 g/mL,加料量0.1000 g,反胶束溶液中含水量18,萃取时间30 m in,萃取温度40℃,增溶水pH 7,KC l浓度0.1 mol/L。     

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.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.