罗非鱼骨胶原蛋白质的提取及其性质

为充分利用鱼片加工废弃物鱼骨中的胶原蛋白质,采用单因素以及正交实验法,研究胃蛋白酶在酸性介质条件下提取罗非鱼骨胶原蛋白质的最佳工艺,精制后的胶原蛋白质采用SDSPAGE电泳、紫外及傅立叶变换红外扫描,圆二色检测,氨基酸分析,热变性温度测定等方法 ,分析胶原蛋白质的理化性质。结果显示:乳酸溶液p H 2.6,温度30℃,料液比1∶30(g/mL),加酶量200U/g,提取时间24h,此工艺条件下的粗胶原蛋白质提取率达到70.28%,得率为12.76%;罗非鱼骨胶原蛋白质含有2条α链和1条β链,属于典型的I型胶原蛋白质;罗非鱼骨胶原蛋白质的主要氨基酸为甘氨酸、脯氨酸、羟脯氨酸、谷氨酸和丙氨酸;罗非鱼骨胶原蛋白质的热变性温度为34.5℃。研究表明,采用胃蛋白酶提取鱼骨胶原蛋白质,提取率和纯度均较高。     

猪皮中胶原蛋白的提取与结构鉴定

以猪皮为原料,使用酶法提取胶原蛋白,对提取条件和过程进行筛选和优化,并对胶原产物的结构性质进行表征。结果表明,胶原蛋白产物的提取率为65.33%;纯度为87.38%;热变性温度在118.79℃;紫外最大吸收波长为203 nm;相对分子质量为3.63×10~5 g/mol;红外光谱和圆二色谱结果显示,产物具有典型的胶原蛋白吸收峰,说明提取出的胶原蛋白三螺旋结构保存完整;十二烷基硫酸钠聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electrophoresis,SDS-PAGE)结果显示所得胶原产物主要由3种亚基组分组成。     

鹿骨胶原蛋白特性的研究

采用酸和酶提取法从鹿骨中提取酸溶性胶原蛋白（ASC）和胃蛋白酶促溶性胶原蛋白（PSC）,利用紫外扫描、傅立叶变换红外光谱、DSC、SDS-PAGE垂直电泳和氨基酸分析仪,研究了鹿骨胶原蛋白的结构、热收缩温度、相对分子量和氨基酸组成。结果表明：紫外扫描分析,鹿骨的ASC和PSC在234nm处均有强烈吸收,具有胶原蛋白的特性;红外光谱说明胶原纤维保留了大量的三股螺旋结构;经DSC测定,鹿骨的ASC和PSC热收缩温度分别为55℃和58℃。SDS-PAGE电泳显示,胶原蛋白含有3条不同的链,α1、α2和β链。氨基酸分析表明,具有典型胶原蛋白的氨基酸组成。     

尖吻鲈鱼鳞和鱼皮胶原蛋白的提取及其理化特性分析

以尖吻鲈鱼鳞和鱼皮为原料,提取并分离纯化酶溶性胶原蛋白,通过十二烷基硫酸钠-聚丙烯酰胺凝胶 电泳（sodium dodecyl sulfate-polyacrylamide gel electropheresis,SDS-PAGE）、氨基酸组成分析、差示扫描量热 （differential scanning calorimetry,DSC）、傅里叶变换红外光谱、X射线衍射和Zeta电位以及溶解度研究,分析 和比较了其主要理化性质。冷冻干燥后鱼鳞和鱼皮胶原蛋白得率（干质量）分别为2.3 g/100 g和47.3 g/100 g; SDS-PAGE结果显示两种胶原蛋白构型均为[α1(Ⅰ)]2α2(Ⅰ),初步判断属于Ⅰ型胶原蛋白;DSC结果显示鱼鳞和鱼 皮胶原蛋白热变性温度（Td）分别为37.54 ℃和36.74 ℃;傅里叶变换红外光谱和X射线衍射结果显示胶原蛋白经 胃蛋白酶处理后仍能保持其完整的三股螺旋结构;Zeta电位结果显示鱼鳞和鱼皮胶原蛋白等电点分别为pH 6.40和 pH 6.64;溶解度研究结果显示两种胶原蛋白在酸性条件和低NaCl质量浓度下均表现出良好的溶解性。     

鲤鱼鱼皮和鱼骨酶溶性胶原蛋白的性质比较

以鲤鱼鱼皮和鱼骨为原料提取得到酶溶性胶原蛋白(PSC),对鱼皮PSC和鱼骨PSC的性质进行比较。电泳结果表明,鱼皮PSC和鱼骨PSC都属于Ⅰ型胶原;2种胶原蛋白中,脯氨酸和羟脯氨酸含量均低于牛皮酸溶性胶原蛋白;粘度测定的结果显示,鱼皮PSC的变性温度为28.1℃,鱼骨PSC的变性温度为30.0℃;差热分析的结果说明,鱼骨PSC的热稳定性高于鱼皮PSC,这与氨基酸分析和粘度分析的结果相一致;傅立叶红外光谱分析结果显示,鱼皮PSC和鱼骨PSC结构具有很大的相似性。     

草鱼鱼鳞、鱼皮和鱼骨酸溶性胶原蛋白特性对比研究

从草鱼鱼鳞、鱼皮和鱼骨中提取酸溶性胶原蛋白(ASC),对其特性进行对比分析。紫外光谱和电泳图谱结果显示,3种ASC紫外特征吸收峰出现位置与I型胶原蛋白紫外特征吸收峰出现的位置基本一致,分子结构都至少含有两条α链;傅里叶红外光谱显示,草鱼鱼鳞、鱼皮和鱼骨ASC在酰胺A带的N-H伸缩均以氢键形成缔合体,酰胺Ⅰ带和酰胺Ⅲ带的特征吸收峰表明鱼鳞和鱼骨ASC的α-螺旋结构保存较完整,鱼皮ASC的α-螺旋结构已经被破坏;3种ASC在热稳定性方面存在一定差异,热变性温度鱼骨ASC(34.5℃)鱼皮ASC(32℃)鱼鳞ASC(31℃),可能与胶原存在的组织和所处的环境有关。     

鲢鱼皮胶原蛋白的提取及性质分析

通过热水浸提,醋酸酸提及胃蛋白酶促提从鲢鱼皮中提取得到水溶性胶原蛋白(RSC),酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC),并分析其部分性质。鲢鱼皮中RSC,ASC和PSC的得率以湿基计分别为13.2%,11.8%和13.6%;RSC,ASC和PSC的紫外光谱分析表明,其最大吸收峰都接近231 nm,但在280 nm处的吸收很小;傅立叶变换红外光谱结果表明鲢鱼皮胶原蛋白具有特殊的三螺旋结构;SDS-PAGE电泳图谱显示鲢鱼皮胶原蛋白有两条α链(α1和α2)和β链,表明该胶原为典型的I型胶原蛋白;鲢鱼皮RSC,ASC和PSC热变性温度分别为27.1℃,31.3℃和30.5℃。这些结果为进一步研究提供了理论依据。     

草鱼皮酸溶性和酶溶性胶原蛋白的提取及性质

本文研究了从草鱼皮中提取酸溶性胶原蛋白(ASC)和酶溶性胶原蛋白(PSC)及其部分性质。草鱼皮中ASC和PSC的提取得率以干基计分别为8.0%和18.6%;对草鱼皮ASC和PSC的紫外光谱分析,最大吸收峰都接近223nm;SDS-PAGE电泳图谱显示草鱼皮胶原蛋白是由两条不同的α链组成,分子量都在100kDa以上,与猪皮I型胶原蛋白相似;草鱼皮ASC和PSC热变性温度分别为33.8、34.5℃,只比猪皮的热变性温度(37℃)低3℃左右。结果表明草鱼皮胶原蛋白在功能食品、医药、化妆品、制药等方面有潜在的应用。     

鮟鱇鱼皮中胶原蛋白的提取及性质研究

采用0.5 mol/L醋酸提取,结合NaCI沉淀法从鮟鱇鱼皮中提取酸溶性胶原蛋白(ASC).并对鮟鱇鱼皮胶原蛋白与Sigma公司的牛跟腱I型胶原蛋白(BATC)进行比较,探讨二者在热变性温度、溶解度、黏度及氨基酸组成等方面的差异.SDS-PAGE结果显示ASC有2条α链(α1和α2链)、β链和γ链,表明该胶原为典型的I型胶原蛋白.DSC分析显示两种胶原的热变性温度分别为22.09℃和38.13℃.氨基酸组成分析结果是亚氨基酸含量ASC低于BATC,分别为14.69%和21.59%;甘氨酸含量相近,分别占所有氨基酸总数的40.05%和38.97%.溶解度结果显示ASC和BATC分别在pH 3和pH 4时达到最大值,在pH 7时两者都呈现最小溶解度;NaCl含量对两者溶解度的影响相同,当其含量低于2%时对溶解度的影响不明显,而随着NaCl舍量的增加,溶解度迅速下降.     

乙酸提取齐口裂腹鱼皮胶原蛋白工艺优化

以齐口裂腹鱼皮为实验材料,选用乙酸提取其中的胶原蛋白。通过单因素实验设计分别从温度、时间、液料比和乙酸浓度4个因素对胶原蛋白提取率的影响进行研究,然后在单因素实验基础上进行响应面优化实验设计,对乙酸提取齐口裂腹鱼皮胶原蛋白的提取参数进行优化。实验结果表明,乙酸提取齐口裂腹鱼皮胶原蛋白的优化工艺条件为温度36.4℃,时间36h,液料比51:1 mL/g,乙酸浓度0.54 mol/L,在此条件下得到的胶原蛋白提取率为67.26%。     

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.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status