从棉子糖肠球菌发酵液中提取γ-氨基丁酸的初步研究

针对实验室筛选到一株高产γ-氨基丁酸(γ-aminobutyric acid,GABA)的棉子糖肠球菌(Enterococcus raffinosus)TCCC11660菌株,研究了壳聚糖絮凝剂预处理该发酵液的工艺条件。以絮凝率为指标,确定了适于GABA发酵液体系的絮凝工艺。结果表明,最佳操作条件为在室温下发酵液pH4.5,壳聚糖用量150mg/L,150r/min快速搅拌加入絮凝剂后25~30r/min慢速养絮15min,絮凝率可达95.2%,GABA保留率为99%。絮凝后的发酵液采用大孔吸附树脂进行脱色处理,筛选出的DA201-CⅡ树脂具有较高的脱色率和GABA得率。实验确定了最佳脱色条件为:25℃,pH4.5,处理体积5BV,脱色流速3BV/h。采用此工艺对GABA发酵液的脱色率达到90.6%,GABA得率为92.5%。     

不同絮凝剂在肠衣废水蛋白质回收中的应用研究

研究了不同絮凝剂回收肠衣废水蛋白质工艺,实验结果表明,聚合硫酸铁最优絮凝工艺条件为絮凝剂聚合硫酸铁用量为0.3g/L,絮凝时间为35min,絮凝pH值为7.0,絮凝温度为30℃。蛋白质回收率达到90.1%,COD去除率达到81.2%;壳聚糖最优絮凝工艺条件为絮凝剂用量为0.3g/L,絮凝时间为35min,絮凝pH值为6.5,絮凝温度为30℃。蛋白质回收率达到83.1%,COD去除率达到76.4%;单从蛋白质去除率和COD去除率出发,聚合硫酸铁是肠衣废水预处理的最佳絮凝剂,但从回收蛋白质再利用角度出发,应选择壳聚糖。     

肉类加工废水中蛋白质的回收试验

研究了不同絮凝剂回收肉类加工废水蛋白质工艺,实验表明,聚合硫酸铁最优絮凝工艺条件为絮凝荆聚合硫酸铁用量0.3g/L,絮凝时间为35 min,絮凝pH值为7.0,絮凝温度为30℃.蛋白质回收率达到90.1%,COD去除率达到81.2%;壳聚糖最优絮凝工艺条件为絮凝剂用量0.3g/L,絮凝时间为35min,絮凝pH值为6.5,絮凝温度为30℃.蛋白质回收率达到83.1%,COD去除率达到76.4%;单从蛋白质去除率和COD去除率出发,聚合硫酸铁是肉类加工废水预处理的最佳絮凝剂,但从回收蛋白质再利用角度出发,应选择壳聚糖.     

磁聚复配物对L-乳酸发酵液的预处理研究

对用磁聚复配物预处理L-乳酸发酵液进行了研究,讨论了pH值、复配物用量、搅拌速度与时间、温度、磁场强度对絮凝效果的影响。实验结果显示,在pH5~6,40 mg/L壳聚糖与100 mg/L Fe3O4复配,200r/min下搅拌5 min,35~55℃,外加磁场(0.5T)作用1 min的情况下,发酵液的絮凝率达到了98.5%,表明磁聚复配物对L-乳酸发酵液中的蛋白质具有优良的絮凝能力,且更大的优势在于显著提高了固液分离的速度。     

γ-氨基丁酸发酵液的絮凝和脱色工艺研究

以壳聚糖作为絮凝剂,对γ-氨基丁酸发酵液的絮凝工艺进行了正交实验优化,确定了最佳的絮凝工艺条件为pH 5.0、壳聚糖用量0.1g/L以及温度20℃,此条件下絮凝率可达97.3%,γ-氨基丁酸损失率仅为1.2%.然后采用大孔脱色树脂对絮凝后的发酵液进行脱色,实验结果表明,用440nm的吸光度能准确表征发酵液中的色素浓度,SD300大孔吸附树脂对GABA发酵液具有较高的脱色率和GABA得率,优化的脱色pH和脱色温度分别为pH 5.0和25℃.该研究结果为从发酵液中分离提纯γ-氨基丁酸奠定了良好的基础.     

甲壳素废水中虾青素与蛋白质絮凝工艺条件的研究

对含有虾青素的甲壳素废水的絮凝工艺条件进行了研究。试验结果表明,采用明矾作絮凝剂效果最佳;较佳的絮凝工艺条件为:55℃,水浴20min,pH为6.0,絮凝剂用量为20mg/L;经凯氏定氮测得蛋白质和虾青素混合物的回收率达到89.1%。     

1,3-丙二醇发酵液的絮凝处理及絮凝细胞的再利用

考察了12种絮凝剂或沉淀剂对1,3-丙二醇发酵液预处理的效果,并探索了壳聚糖絮凝Klebsiellapneumoniae细胞再利用的可行性。以菌体和蛋白质去除率为指标,从12种絮凝剂中筛选出壳聚糖为有效的絮凝剂,并确定了适宜的工艺条件为:温度37℃,搅拌转数300 r/min,pH 5.0,壳聚糖分子质量4万u,浓度0.5 g/L,搅拌20 min,静置15 min。发酵液的菌体和蛋白质去除率分别为99.97%和91.56%。絮凝细胞的发酵实验表明,絮凝的K.pneumoniae可再次利用,菌体浓度高达11.4(OD值)。     

天然高分子絮凝剂对葡萄酒泥分离脱汁的研究

为充分利用酒泥,提高葡萄酒出酒率,选用壳聚糖和木质素作为天然高分子絮凝剂对红葡萄酒泥进行分离脱汁。试验考察了2种絮凝剂的絮凝效果,优化絮凝剂用量、絮凝温度、搅拌时间工艺参数,得出在30℃下,使用壳聚糖2.5 g/100 mL酒泥搅拌6~10 min可达到较好效果,回收率超过60%。壳聚糖絮凝汁和木质素絮凝汁理化指标均符合国家标准。     

气相色谱法检测发酵液中苯乳酸含量的研究

建立了气相色谱定量检测发酵液中苯乳酸的方法。在确定的色谱条件下16min内能较好的分离苯乳酸,在0.05～20mg/mL浓度范围内线性良好(r=0.9995),其检测限为1.2ng。从酯化处理至气相色谱检测,方法的回收率在94.74%～98.42%范围之内,相对标准偏差为2.71%～3.55%。该方法简便、快速、准确,适于发酵液中苯乳酸的测定。     

树莓果酒发酵液絮凝剂的筛选优化

研究分别通过对无机盐类絮凝剂、无机高分子类絮凝剂和有机高分子聚合物类絮凝剂的单因素筛选试验;通过对有机高分子聚合物类絮凝剂-壳聚糖的正交试验,优化出树莓果酒发酵液的最佳絮凝剂-壳聚糖,并得到壳聚糖用于树莓果酒发酵液絮凝的最佳条件：添加浓度150mg/L,在pH4.0时,室温下搅拌15min,絮凝效果最好。     

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.