牡蛎和泥蚶过氧化氢酶的性质比较

对牡蛎和泥蚶过氧化氢酶(Cat)的性质进行比较。结果表明两者的PAGE谱带于同一位置，相对分了质量约为230kD，含有4个亚基。影响酶活力的温度相同，50℃以上酶活力明显下降；酶的最适pH5～8，但牡蛎Cat在酸碱条件下酶活力下降明显。     

应用氧化棉织物固定过氧化氢酶的研究

以高碘酸钠氧化棉织物为载体固定过氧化氢酶，研究其固定化的主要条件，考察了固定化酶的性质。试验结果表明，过氧化氢酶固定在氧化棉织物上时，棉织物的最佳氧化条件为：NalO4浓度0．20mol／L，氧化时间8h，氧化浴pH值6．0，氧化温度40℃；过氧化氢酶固定化的条件为：过氧化氢酶用量0．20mL／（g棉织物），固定化时间24h。固定化酶的最适温度比游离酶提高了约10℃，使用温度范围变宽；固定化酶的最适pH值为7．0与游离酶相同，在酸性范围内稳定性较游离酶差，但在弱碱性范围内稳定性比游离酶好。     

重组凝乳酶的酶学特性研究

对重组毕氏酵母菌分泌表达的凝乳酶进行酶学特性研究.结果表明,该酶最适凝乳温度为45℃;最适pH值为5.0;在45℃以下可以保持相对稳定的活力,55℃(6 min)丧失全部活性;酶在4.0～7.0之间凝乳活性稳定;该酶在押肽酶、亮抑酶肽、苯甲基磺酰氟、1,10-菲咯啉等蛋白酶抑制剂的作用下均保持了大部分的活性,浓度为1μmol/L胃蛋白酶抑制剂Pepstain A可以明显抑制重组凝乳酶的活性.研究结果证明了重组凝乳酶与商品凝乳酶酶学特性相近,可以应用于干酪生产.     

苹果过氧化氢酶的纯化及性质研究

新鲜苹果经匀浆、抽提、硫酸铵盐析、DEAE-Cellulose柱层析,获得纯化苹果过氧化氢酶(CAT)液。纯化CAT酶液蛋白含量26.8mg/mL,活力843Units/mL,比活力31.5Units/mg。经过温度和pH考察,酶的最适温度为50℃、最适pH值为5.0。金属离子影响为:Cu2 和Mn2 对该酶有不同程度的激活作用,Na 对该酶有一定程度的抑制作用。以过氧化氢为底物,Lineweaver-Burk双倒数作图法求得此酶的Km和Vmax分别为2.27mmol/L和2.5μmol/min。     

大豆过氧化氢酶的分离纯化及性质研究

新鲜大豆芽经匀浆、磷酸缓冲液抽提、硫酸铵分级沉淀、DEAE-Sepharose离子交换层析、Superdex-200凝胶过滤层析,获得电泳纯的过氧化氢酶。该酶酶活回收率为30.92%,纯化倍数为293.09,酶比活力达到26 322.43 U/mg。该酶全分子质量为234.9 kD,亚基分子质量为57.42 kD;最适pH值为7.2,最适温度为30 ℃,在pH 4.0～10.6及25～35 ℃范围内有较好的稳定性;在30 ℃、pH 7.2条件下测得该酶对过氧化氢的Km值为31.82 mmol/L;十二烷基硫酸钠、草酸、Ag+、Cu2+对该酶有强烈的抑制作用,Pb2+对该酶有双重作用,低浓度时有激活作用而高浓度时抑制酶活性。     

海洋低温过氧化氢酶菌株的筛选及酶学性的研究

从渤海湾海域海泥海水混合物中分离获得一株产低温过氧化氢酶菌株CZA1202,通过菌株的形态特征、生理生化和16 S rDNA序列鉴定为Serratia liquefaciens.对其醇学性质进行初步研究,CZA1202所产过氧化氢酶最适反应温度30℃,最适pH 7.0,在pH7.0～9.0范围内较稳定,在35℃保持60 min条件下,酶活可保留70％.初始酶活达到107.8 U/mL.     

工业酿酒酵母重组β-1,3-1,4-葡聚糖酶部分酶学性质的研究

用刚果红法测定β-1,3-1,4-葡聚糖酶的酶活力,研究重组酿酒酵母(S.cerevisiae)菌株SC-βG分泌表达的重组β-1,3-1,4-葡聚糖酶的部分酶学性质,并与出发菌株枯草芽孢杆菌(B.subtilis)表达的原始酶的性质进行比较。结果表明,重组酶保持了与原始酶相同的底物专一性。重组酶的最适反应温度为35℃,而原始酶为55℃。重组酶的热稳定性也发生了改变,40℃热处理20min只保留63.4%的最初酶活力,但温度再升高时对热处理敏感度降低,70℃的热处理20min仍保留45.9%的最初酶活力;而原始酶50℃时稳定,60℃以上的热处理酶活力损失很大。与原始酶相比,重组酶的最适pH值下降为pH5.0,而原始酶为pH6.5;相比原始酶在pH7.0有最大稳定性,重组酶在pH5.5时有最大稳定性。重组β-1,3-1,4-葡聚糖酶的最适反应条件与原始酶相比更接近啤酒的实际生产条件。     

产过氧化氢酶的乳酸菌的筛选和产酶条件的研究

从不同生态环境分离到21株产酸菌,从中筛选出一株产乳酸力强、产胞外过氧化氢酶活力较高的菌株TL012,其产酶最适温度为38℃,初始培养始pH6、培养50小时,在脱脂奶粉培养基中产酶可达98.40μ/ml。     

工业酿酒酵母重组β-1,3-1,4-葡聚糖酶部分酶学性质的研究

用刚果红法测定β-1,3-1,4-葡聚糖酶的酶活力,研究重组酿酒酵母(S.cerevisiae)菌株SC-βG分泌表达的重组β-1,3-1,4-葡聚糖酶的部分酶学性质,并与出发菌株枯草芽孢杆菌(B.subtilis)表达的原始酶的性质进行比较。结果表明,重组酶保持了与原始酶相同的底物专一性。 重组酶的最适反应温度为35℃,而原始酶为55℃。重组酶的热稳定性也发生了改变,40℃热处理20min只保留63.4%的最初酶活力,但温度再升高时对热处理敏感度降低,70℃的热处理20min仍保留45.9%的最初酶活力;而原始酶50℃时稳定,60℃以上的热处理酶活力损失很大。与原始酶相比,重组酶的最适pH值下降为pH5.0,而原始酶为pH6.5;相比原始酶在pH7.0有最大稳定性,重组酶在pH5.5时有最大稳定性。重组β-1,3-1,4-葡聚糖酶的最适反应条件与原始酶相比更接近啤酒的实际生产条件。     

山药苯丙氨酸解氨酶特性的研究

本文研究了山药苯丙氨酸解氨酶(PAL)的动力学特性。结果表明,PAL最适底物浓度为1mmol/L,底物浓度过高或过低都对酶活力不利。PAL在硼酸-氢氧化钠缓冲液中适宜的pH范围为7.6～9.2,最适pH有2个:pH8.0和pH8.8。PAL不耐酸碱,尤其不耐碱。PAL适宜的温度范围为35～55℃,最适反应温度为45℃,超过70℃则容易钝化。L-酪氨酸和L-半胱氨酸对PAL活性都有抑制作用,抑制程度随抑制剂浓度增加而增强。L-酪氨酸的抑制作用较强,是PAL的竞争型抑制剂。L-胱氨酸对PAL的活性无影响。     

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.     

Review of techniques to manufacture micro-hydrogel particles for the food industry and their applications

Microgels are ‘soft’ microscopic cross-linked polymeric particles that are being increasingly exploited in a variety of industries for rheology control, encapsulation and targeted delivery. They are valued because of the ability to tune their functionality to address specific applications in oil recovery, coatings, drug delivery, cosmetics, personal care and foods. Food microgels are typically biopolymer hydrogels in the form of microspheres, nanospheres (also called nanogels), spheroids and fibres. The utilisation of engineered microgels in foods has so far been limited, despite their great potential to address several needs in the food industry, including: satiety control, encapsulation of phytonutrients and prebiotics, texture control for healthier food formulations (e.g. reduced fat products), and targeting delivery to specific areas in the digestive tract. We review the scientific and patent literature on the utilisation and manufacturing methods for producing microgels with an emphasis on micro-hydrogels for food applications.     

12—A CRITIQUE OF SOME HYPOTHESES RELATING TO THE HETEROGENEITY OF THE HIGH-SULPHUR PROTEINS OF WOOL

Joubert and Burns prepared a large number of fractions from the high-sulphur proteins of wool and estimated their molecular weights and amino-acid compositions. Their data have been re-examined in order to look for statistically significant interrelations between amino acids and between the proportion of various amino acids and molecular weight. Statistical analysis of the data is also used to examine the credibility of some hypotheses concerning the mechanism of keratin biosynthesis and to provide further evidence for the existence of families of proteins within the high-sulphur fractions of wool.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of     

The Latest Data about Development of Chinese Printing Industry in 2013

In the 2014 China（Shanghai）International Printing Week,Director Wang Yanbin released the latest data about development of Chinese printing industry in 2013.According to statistics,in 2013,the total output value of Chinese printing industry exceeded 1trillion Yuan for the first time,reaching 1.03985 trillion Yuan.There were 105,000 printing enterprises in China,employees were 3.415 million.The total asset was 1.06247 trillion Yuan;     

The State Council Issued "Directory of Government Approved Investment Projects(2013 Edition)"

正On December 2nd,2013,the State Council issued the notification of"Directory of Government Approved Investment Projects(2013 Edition)"(hereafter referred to as"notification").It is pointed out in the"notification"that in order to further deepen reforms in investment systems and administrative examination and approval systems,simplify administrative procedures and delegate powers to lower levels,earnestly     

China textile machinery: taking off in progress

正Among the 1600 exhibitors who take apart in the ITMA ASIA+CITME2014 2/3 are Chinese manufactures.If the numerous figures failed to attract your attention,the increase of quality should draw your focus.To adopt the demand of developing textile machine market,domestic textile machinery enterprises now follow the slogan of"technology drives development"to enhance product competitiveness.Our domestic sellers will showcase product ranging from spinning,weaving,dyeing and printing,     

Top Ten News of China's Paper Industry 2013

On December 24th, 2013, the meeting on the selection of top 10 news of China＇s paper industry 2013 sponsored by 〈China Paper Newsletters〉 was held in Beijing. The yearly selection of the top l0 news, which began in 2000, has become a brand activity widely recognized in the industry thanks to the support from the authorities at all levels and public participation.