Enterobactersp．SYA2乳糖酶酶学性质研究

采用硫酸铵盐析对Enterobactersp．SYA2乳糖酶进行分级沉淀,研究了该酶的最适作用温度、热稳定性、最适作用pH、pH稳定性及金属离子的影响。结果表明：选取硫酸铵的饱和度30％～85％进行分级沉淀,分级沉淀后得到乳糖酶的比活为45．85U／mg;该酶最适作用温度为40℃～45℃,在35℃和40℃处理时酶活损失不大,在45℃和50℃处理时酶活损失较大,最适作用pH为6．5,pH在6．0－8．5酶活最为稳定,Mg^2＋、Mn^2＋、Na^＋对该酶有一定激活作用,Zn^2＋,Cu^2、Fe^2＋对该酶有不同程度的抑制作用,当酶添加量为1U／mL,乳清水解率3h达50％;而添加量为2U／mL时乳清水解率1h达50％。     

低温α-淀粉酶产生菌GS230发酵条件与酶学性质研究

对分离自连云港海域的低温α-淀粉酶产生菌Pseudoalteromonas sp．GS230进行了产酶条件的优化和酶学性质的研究。结果表明,该酶在0．4％可溶性淀粉、0．25％牛肉膏、1．5％蛋白胨以及5％接种量、培养32h产酶量达到最高。对低温仪．淀粉酶性质进行研究发现,该酶的最适作用温度和pH值分别是30℃和pH8．0、0℃时相对酶活达28％。对酶稳定性的研究发现,该酶对热敏感,30℃半衰期为1．5h,Ca^2＋可以提高酶的稳定性;在反应体系中添加5mmol／L Ca^2＋,30℃保温1．5h,残余酶活达93％。Na^＋K^＋、Ca^2＋等对酶有激活作用,而Pb^2＋、Cu^2＋、Fe^3＋等强烈抑制酶活性。     

黑曲霉产β-呋喃果糖苷酶酶学性质研究

对来源于黑曲霉的β-D-呋喃果糖苷酶的酶学特性进行了研究。结果表明,β-D-呋喃果糖苷酶的最适pH值为5．0,最适温度为50％。在40℃～60℃、pH值5．0～7．0其具有较好的稳定性。金属离子对β-呋喃果糖苷酶活性有影响。Mn^2＋和Ca^2＋能明显增强酶活,而Cu^2＋和Ag^2＋能抑制酶活。     

真菌α-淀粉酶产生菌的筛选及酶学特性的研究

通过对实验室中保藏4种真菌菌株进行液体发酵与固体发酵研究，筛选出最佳的α-淀粉酶产生菌米曲霉FSO179，固体发酵产酶水平为910．3u／g，液体产酶水平为656.6u／mL。该酶酶学特性研究表明：该酶作用的最适温度为55℃，50℃保温30min仍保留80％；最适作用pH为4．0，pH稳定范围为3.5-6.0之间。Fe^2＋、Ba^2＋、Cu^2＋、Mn^2＋、Fe^3＋金属离子对酶具较强抑制作用。而Ca^2＋对酶具有一定激活作用。     

米黑毛霉凝乳酶酶学性质研究

研究了米黑毛霉凝乳酶的最适温度、最适pH、热稳定性,探讨了金属离子对酶活力的影响,加酶量对酶反应的影响,测定了酶的蛋白水解活力和酶的K^m与V^m值。结果显示：酶的最适温度为70℃;最适pH6;酶液在65℃保温10min,酶活损失达96％;Na^＋和K^＋对酶稍有抑制作用,Fe^2＋对酶有促进作用,Cu^2＋对酶有强烈的抑制作用;减少酶的添加量,在规定时间内凝乳会导致凝乳酶酶活测定结果偏大;凝乳酶蛋白水解活力为1048U／g;Km为190．84g／L,Vmax=7．8678g／s。     

气单胞菌属JH菌株脂肪酶酶学特性的研究

从JH菌体中提取脂肪酶,并在不同的反应条件下对其酶学性质进行研究。该脂肪酶最佳反应温度和缓冲液pH制分别为40℃和7．0。该酶具有较强的热稳定性和pH稳定性：经过30℃、40℃处理60rain仍然保持90％以上的酶活;用pH3．5～9缓冲液处珲该酶,仍然保持80％以上的酶活。Ca2＋、Mg2＋对该脂肪酶具有明显的激活作用,尤其是Mg2＋作用最为显著,与对照组相比提高了38．8％,Zn2＋、Fe2＋对该脂肪酶有显著的抑制作用,Cu2＋对脂肪酶的影响不显著。用双倒数法作图得到Vmax=2．13×10^-2mol／L,Km=0．639（mmol／mL）min-1。表面活性剂吐温-80对脂肪酶有促进作用。该菌株产生的脂肪酶町以往温和的反应条件下作用。     

Purification and Characterization of Intracellular α-galactosidase from Rhizopus sp. AOI

根霉Rhizopus sp．A01的菌丝体破碎液依次经过三相分离、SephaαexG-100凝胶过滤获得了电泳纯的α-半乳糖苷酶,纯化了54．8倍,总酶活回收率达到27．3％,在SDS-PAGE上显示相对分子质量为85．6ku的单-条带,凝胶过滤表明该酶表观相对分子质量为302ku。该酶水解对硝基苯-α—D-吡喃半乳糖苷的最适pH值为4．5,最适温度为55％,表观Kn值为（0．242±0．027）mmol／L,表观Kcat／Km值为4．089×10^5L／（mol·s）;对蜜二糖和棉子糖有弱的水解作用,水解速度依次为138．3μmol／（h·mg）、19．7μmol／（h·mg）。水解活性受Fe^2＋和Fe^2＋的显著激活,但受Mn^2＋、Cu^2＋、Hg^＋和Mg^2＋等离子的强烈抑制。该酶活性在pH4．0～8．2保持稳定,在50℃时保温90min,残余酶活达到了48％。     

生淀粉糖化酶的菌种筛选及酶学研究

从自然界分离到一株高酶活性的生淀粉糖化酶菌株黑曲霉Sx。在最适产酶条件;固体培养基pH6.5,固水比1：1.6,30℃发酵24h酶活达382u/g。经纸层析鉴定酶解产物为葡萄糖。粗酶液在贮藏时,当酶液中的SDS浓度达6mg/ml时,30℃保藏10天,酶活保持不变。分析经初步分离提纯的酶的性质得：以玉米淀粉为底物时,该酶最适pH4.5,最适酶反应温度为60℃。pH4.0-7.0范围内酶活力稳定,酶具有较强的热稳定性,80℃保温1h以后,酶活力仍能保持15％。金属离子等对酶的影响为：Ag^＋、Sn^2＋对酶有强烈抑制作用;Hg^2＋、Zn^2＋、Mn^2＋、Cu^2＋有抑制作用：EDTA、Ca^2＋、Fe^2＋对酶无影响;Co^2 、K^ 有一定的激活作用。     

产生淀粉酶菌株的诱变选育及酶学性质研究

以产生淀粉酶菌株Aspergillus niger AF-0为出发菌株,先后经紫外（UV）、亚硝基胍（NTG）诱变,选育得到了一株产酶活性较高的突变株,其所产马铃薯生淀粉酶的酶活力达43．8U／mL,比原初酶活力19．3U／mL提高了1．3倍。在此基础上,对该酶的部分酶学性质进行了研究。结果表明,该酶的最适反应温度为55℃,在60℃以下稳定;最适反应pH为4．0,在pH3．5—5．0范围内稳定;Mn^2＋,Fe^2＋,Zn^2＋,Mg^2＋,Ca^2＋,Ba^2＋对该酶有一定的激活作用,而Cu^2＋,K^＋,Na^＋则抑制酶的活性;该酶以形成孔洞的方式由外向内作用于马铃薯淀粉颗粒。     

宇佐美曲霉木聚糖酶粗酶性质研究

本文对宇佐关曲霉(Asp．usamii)产木聚糖酶的产酶进程进行了分析，28℃固态静置培养72h，酶活力可达到7442IU／g干曲。粗酶酶学性质研究表明：该木聚糖酶的最适反应温度50℃，低于50℃时较稳定；酶的最适pH4．6，pH稳定范围为pH5．0-10．0。Ca^2 对酶有激活作用，而Mn^2 、Mg^2 、Ba^2 则具有强烈的抑制作用。     

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.