反复冻融法破壁啤酒废酵母的研究

对反复冻融法破壁啤酒酵母的效果进行了初步探索.通过研究水分含量、反复冻融次数对啤酒酵母破壁率及蛋白溶出率的影响分析,结果表明,在酵母粉含水量为20%,反复冻融次数为3次时,破壁率可达到35%,可溶性蛋白溶出率为50.29%.     

螺旋藻蛋白提取方法比较研究

采用超声波法、高压均质法和反复冻融法对螺旋藻细胞进行破碎,确定破碎条件和螺旋藻蛋白溶出率。结果表明:在各自的最佳提取条件下,超声波法得到的蛋白溶出率为71.51%,高压均质法得到的藻胆蛋白溶出率为73.87%,反复冻融法得到的蛋白溶出率为72.03%。     

啤酒废酵母综合破壁法提取酵母味素技术

本文研究了高压均质、酶法溶胞、冻融法三种细胞壁破碎法对啤酒废酵母抽提物（酵母味素）的得率、蛋白质的转化率及氨基氮溶出率的影响。实验结果,在适宜的自溶条件下,利用综合破壁法可使酵母抽提物中上述三项指标显著提高。     

啤酒废酵母综合破壁法提取酵母味素技术

研究了高压均质、酶法溶胞、冻融法三种细胞壁破碎法对啤酒废酵母抽提物(酵母味素)的得率、蛋白质的转化率及氨基氮溶出率的影响.实验结果,在适宜的自溶条件下,利用综合破壁法可使酵母抽提物中上述三项指标显著提高.     

反复冻融和超声协同作用破碎酵母细胞

利用反复冻融法和超声波技术相结合的方法破碎啤酒酵母细胞壁,研究协同作用对酵母细胞破壁率的影响。研究结果表明:啤酒酵母先经反复冻融处理(加水量为25%、冻融4次),然后经过超声处理(超声功率400 W,每次辐射时间11 s,超声总时间14.5 min,酵母浓度20 mg/mL)进行破碎,破壁率达到了89.31%,且破壁率是反复冻融单独作用的2.4倍,是超声波单独作用的1.5倍。     

蛋白核小球藻冻融破壁条件优化及对其抗氧化活性的影响

探讨了蛋白核小球藻反复冻融破壁工艺,同时研究了其对抗氧化活性的影响。考察了冻融次数、冻融时间和细胞密度对蛋白核小球藻破壁率的影响,在单因素的基础上通过响应面法优化破壁工艺参数。研究结果表明,蛋白核小球藻破壁最佳工艺条件为冻融次数5次,冻结时间1.1 h,细胞密度1.94×10~(-7),在此条件下,蛋白核小球藻破壁率为(62.18±1.2)%。同时利用DPPH、O_2~-·清除能力的强弱评价反复冻融法对蛋白核小球藻抗氧化活性的影响,结果表明,经反复冻融蛋白核小球藻对DPPH和O_~2-·清除能力均优于未经冻融处理的对照组。     

啤酒废酵母综合破壁法提取酵母味素技术

研究了高压均质、酶法溶胞、温差破壁3种细胞壁破碎法对啤酒废酵母抽提物(酵母味素)的得率、蛋白质的转化率及氨基氮溶出率的影响.结果表明,在适宜的自溶条件下,利用综合破壁法可使酵母抽提物中酵母味素得率、蛋白质的转化率及氨基氮溶出率显著提高.     

反复冻融增强葛仙米藻胆蛋白抗氧化特性研究

研究反复冻融处理对葛仙米藻胆蛋白抗氧化特性的影响,测定其对抗氧化活性和对H2O2诱导的红细胞溶血和脂质过氧化的抑制作用。结果发现:经过反复冻融处理的葛仙米藻胆蛋白以pH7.3的50mmol/L的磷酸氢二钾-氢氧化钠为溶剂溶解的样品对ABTS+.的抗氧化活性和对H2O2诱导的红细胞溶血和脂质过氧化抑制作用强于其他处理,同时对铁离子的还原能力也较强,主要原因是反复冻融处理增加了葛仙米藻胆蛋白的溶出量,改变其中藻蓝蛋白和藻红蛋白的比例关系。     

破壁方法对嗜热链球菌SP1.1胞内乳糖代谢关键酶活性的影响及其条件优化

通过超声波破壁法、溶菌酶破壁法、反复冻融法和机械破壁法4种不同破壁方式对嗜热链球菌SP1.1进行破壁处理,对菌体的破壁率、提取的β-半乳糖苷酶和乳酸脱氢酶两种胞内酶的活力进行分析比较,以确定适合于嗜热链球菌细胞破壁方法及其最佳条件。结果表明：这4种菌体细胞破壁效果存在很大差异,其中经溶菌酶处理胞内酶提取效果最好,破壁率可达99.87%,β-半乳糖苷酶酶活力为0.387U,乳酸脱氢酶酶活力为2.375U,与其他3种方法的破壁效果差异极显著(P＜0.01)。优化溶菌酶破壁条件,当处理8mL菌浓度为1.3×109CFU/mL的样品时,确定处理最佳温度为37℃,时间为30min,酶(20000U/mL)用量为1mL,此时破壁率可达99.99%,β-半乳糖苷酶酶活力为0.429U,乳酸脱氢酶酶活力为2.431U。     

小球藻海藻油提取中不同破壁方法的研究

目的是寻找一种安全有效的破壁方法,用以小球藻海藻油的批量提取.方法采用超声波、反复冻融2种破壁方法,分别对三种不同密度的小球藻进行了破碎研究,并研究了不同破壁方法对小球藻海藻油提取率的影响.结果三种不同密度的小球藻经超声破壁后,破壁率均能达到90%以上,经反复冻融4次后,破壁率均能达到50%以上.但随小球藻密度增大,超声破壁时间延长,并且会产生大量的热量,为保护海藻油中的活性物质,操作过程需要冰浴保护;而小球藻密度对反复冻融破壁影响较小.小球藻破壁后有利于海藻油的提取,高密度小球藻(1.55×109个/mL)经超声破壁及反复冻融破壁后,海藻油提取率相当,分别为0.0235g/mL和0.0230g/mL.结论反复冻融破壁方法可用于高密度小球藻的破壁,更适合海藻油的大规模提取.     

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.