高富硒酵母菌诱变选育研究

对36株不同来源的酵母菌进行了硒耐受性分析和比较,获得1株硒耐受性和富硒能力较强的热带假丝酵母菌(Candida tropicalis)菌株1254。以该菌株为出发菌株,进行了亚硝基胍诱变和亚硒酸钠抗性筛选、紫外线诱变和乙硫氨酸抗性筛选等两轮突变和筛选,获得突变菌株1254-6-1,其生物量、总硒含量、有机硒的含量及转化率达到7.60 g/l、5 626.00μg/g、4 879.99μg/g、86.74%,分别为原始出发菌株的1.85倍、7.90倍、9.35倍、1.18倍;各种氨基酸的含量均高于出发菌株,其中蛋氨酸和胱氨酸的含量分别是出发株的135%和194.10%。     

高生物量富硒酵母菌的选育

以酿酒酵母PT为出发菌株,采用梯度浓度筛选的方法对其进行驯化,得到1株生物量较高和对亚硒酸钠抗性较高的菌株GB-1。对其进行紫外诱变处理,当致死率达91.85%时,获得多株突变株。通过多次平板初筛和摇瓶复筛,得到1株高生物量富硒酵母UV-PT。采用响应面法对富硒酵母UV-PT发酵条件进行了优化。借助于SAS软件,首先利用Plackett-Burman试验设计筛选出影响富硒的3个主要因素,即转速、温度、初始pH值。在此基础上,再利用Box-Behnken试验设计及响应面分析法对发酵条件进行优化,确定最佳发酵条件:转速为203r/min,发酵温度为30.3℃,初始pH值为4.52。结果表明,优化后富硒酵母的生物量和含硒量分别为10.62g/L、1003.26μg/g,硒总含量为10654.62μg/L,为出发菌株的1.62倍。     

富硒酵母的选育及其发酵条件的优化试验

通过对一株耐硒酵母进行UV和60Co逐级诱变,获得一株产量高的突变株Y7,发酵液的硒总含量达19mg/L,是出发菌株的1.58倍,经多次传代试验,证明其稳定性良好。通过单因素、L16(37)正交试验对其发酵培养基和培养条件进行优化,试验表明富硒酵母发酵培养基的最佳配方是:蔗糖6%,牛肉膏1%,蛋白胨1%,K2HPO4 0.15%,亚硒酸钠35μg/L;最佳培养条件:初始pH为4.0,温度32℃,装液量60mL/250mL摇瓶,转速200r/min,10%(v/v)接种量,培养48h。富硒酵母的硒总含量达23mg/L以上,是出发菌株的1.92倍。     

高生物量富硒酵母菌的选育

以酿酒酵母PT为出发菌株,采用梯度浓度筛选的方法对其进行驯化,得到1株生物量较高和对亚硒酸钠抗性较高的菌株GB-1.对其进行紫外诱变处理,当致死率达91.85%时,获得多株突变株.通过多次平板初筛和摇瓶复筛,得到1株高生物量富硒酵母UV-PT.采用响应面法对富硒酵母UV-PT发酵条件进行了优化.借助于SAS软件,首先利用Plaekett-Burman试验设计筛选出影响富硒的3个主要因素,即转速、温度、初始pH值.在此基础上,再利用Box-Behnken试验设计及响应面分析法对发酵条件进行优化,确定最佳发酵条件:转速为203r/min,发酵温度为30.3℃,初始PH值为4.52.结果表明,优化后富硒酵母的生物量和含硒量分别为10.62g/L、1003.26ug/g,硒总含量为10654.62ug/L,为出发菌株的1.62倍.     

高富硒酵母菌株的筛选及其富硒特性分析

以酿酒酵母（Saccharomyces cerevisiae）为出发菌株，NaN3为诱变剂、H2O2为选择压力进行菌株诱变筛选，以总硒及有机硒的含量与产率、硒磷酸合成酶（SPS）活性和蛋白硒含量为评价指标进行菌株富硒特性研究。结果表明，经10 mol/L NaN3处理40 min和2.50%H2O2筛分，从出发菌株中得到两株富硒水平高、富硒能力稳定的菌株HXS-01和HXS-02，经48 h摇瓶富硒培养后，菌株HXS-01和HXS-02总硒和有机硒含量及产率、SPS活性和蛋白硒含量分别比出发菌株高3.4～4.0倍、2.9～3.5倍、0.7～1.1倍和0.9～1.1倍，且以菌株HXS-02的富硒能力更高，其总硒含量和产率分别为2 303.97 μg/g和7 945.19 μg/L，有机硒占总硒的百分比超过97%。利用H2O2作为一种新的选择压力可以有效筛选出具有高SPS活性的富硒酵母菌株。     

硒浓度梯度驯化结合紫外诱变法选育富硒酵母菌研究

为获得高产富硒酵母,通过硒浓度梯度驯化啤酒酵母Sac.cerevisiae Fec205、戴氏酵母Sac.delbrueckii Fec209、热带假丝酵母Candida tropicalis Fec2011等3株酵母菌,结果显示啤酒酵母Sac.cerevisiae Fec205比其他2株酵母的耐硒性能更强。因此以啤酒酵母Sac.cerevisiae Fec205为原始菌株进行紫外诱变以提高其富硒能力。通过硒抗性筛选,挑取出6株生长快、菌落大的突变菌株单菌落。取发酵培养基中生物量大的3株酵母菌Sac.cerevisiae Y-3,Y-4,Y-1,接种于硒浓度为40μg/ml发酵培养基,结果显示选育出的3株诱变后的啤酒酵母Sac.cerevisiae Y-3,Y-4,Y-1的硒含量分别为932、832、915μg/g,其中最高的Y-3比原始菌株啤酒酵母Sac.cerevisiae Fec205的硒含量增长50.08%、生物量提高了50.97%。     

富硒酵母中硒蛋氨酸的GC-MS/MS测定

建立酵母中硒蛋氨酸含量的气相色谱——串联质谱法(GC-MS/MS)分析方法。比较3种富硒酵母中硒蛋氨酸检测样品的提取方法,优化硒蛋氨酸的酶解提取条件;以氯甲酸乙酯为衍生化试剂,2-氯苯丙氨酸为内标物,采用选择离子模式对衍生物进行GC/MS/MS检测。结果表明,硒蛋氨酸的回收率为90.0%～97.0%,检测限为4μg/L,方法精密度(RSD)为7.8%。该方法简单快捷、定量准确、灵敏度高。     

富硒益生菌的筛选及其富硒条件的优化

为了获得能耐受较高亚硒酸钠质量浓度和具有富硒能力的益生菌菌株,对7株酵母菌和12株乳酸菌进行了筛选。结果表明,所有菌株均能在亚硒酸钠质量浓度为20~80μg/m L的平板上生长,乳酸菌YQRS菌株和酵母菌FJYJM3菌株具有较高的耐受性和富硒能力。对它们进行发酵条件的优化,表明YQRS菌株在亚硒酸钠添加量为15μg/m L、添加硒的时间为对数期前期时,富硒效果最好,菌体生物量为2.66 g/L,总硒含量能达到2 300.26μg/L。而FJYJM3菌株在亚硒酸钠添加量为20μg/m L,添加硒的时间为对数期前期时,富硒效果最显著,生物量能达到4.86 g/L,总硒含量能达到5 790.99μg/L。     

鸡腿菇菌丝深层培养富硒的研究

通过正交试验,从4株鸡腿菇菌株中筛选出1株具有较高生物量和较强富硒能力的鸡腿菇菌株CcⅢ,并探讨了其耐硒和富硒特性。结果表明,CcⅢ菌株具有一定的耐硒能力和很强的富硒能力,其固态培养最大耐硒浓度为10μg/mL,液态培养最大耐硒浓度为4μg/mL。在硒浓度2μg/mL时,菌丝体生物量为4.11 g/L,富硒量246.74μg/g,富硒率为50.57%,有机化程度高达92.95%。     

野生灵芝的分子鉴定及富硒特性研究

从烟台昆嵛山分离到-株野生灵芝G1-01,根据rDNA ITS序列的系统发育分析,将其鉴定为赤芝(Ganoderraa lucidum (Fr.)Karst).通过对这株野生灵芝在液体培养基中的耐硒能力测定以及小吲培养时间的富硒特性考察,表明该野生灵芝菌株具有较强的富硒能力,其菌丝硒含量达到5.14mg/g,富硒率达到4.05%,分别为对照菌株SK5的2.4倍和1.5倍.     

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.