苦瓜果实中多糖的分离纯化及性质分析

以苦瓜果实为材料,经热水抽提、乙醇沉淀和Sevag 法去蛋白后获得了苦瓜果实粗多糖(MCP)。MCP 经DEAE- 纤维素柱离子交换柱层析分离得到4 个级分MCP-A、MCP-B、MCP-C 和MCP-D。MCP-A 经Superdex G-100 柱进一步纯化得到苦瓜果实多糖MCP-A1 组分。MCP-A1 经高效凝胶渗透色谱法(HPGPC)鉴定为均一组分,测定其平均分子量为93577D。经过对其理化性质鉴定表明,MCP-A1 不含蛋白质、核酸,含有糖醛酸,为非淀粉类多糖。红外光谱扫描结果表明,其具有典型的多糖吸收峰。     

一种具有自由基清除活性的酸性苦瓜多糖的分离纯化及单糖组成分析

苦瓜粗多糖(MCP)经DEAE-纤维素凝胶柱层析及Sephadex G-100凝胶柱层析纯化后,得到多糖组分MCP Ia,经紫外光谱分析及醋酸纤维素薄膜电泳法纯度检验,结果表明MCP Ia是单一组分。HPLC分析其单糖组成为L-鼠李糖、D-木糖、D-果糖和D-半乳糖,单糖物质的量比为4.4:2.3:1:5.7,另外,MCP Ia还可能含有葡萄糖;MCP Ia红外光谱表明:苦瓜多糖存在分子内和分子间的氢键,分子中存在C—H键伸缩振动,存在—OH的变形振动,存在呋喃糖苷吸收峰,是典型的多糖类化合物。     

桃胶多糖的提取分离及组成性质研究

从原桃胶中提取分离得到桃胶多糖,并研究其组成性质.采用热水浸提、乙醇沉淀、Sevage去蛋白的方法提取分离,得到桃胶多糖;气相色谱法测定其单糖组成;高效凝胶过滤色谱法测定其相对分子质量;红外光谱法测定其糖苷键类型.结果表明:桃胶多糖主要由半乳糖和阿拉伯糖组成,另外还含有少量的甘露糖、鼠李糖及葡萄糖,其摩尔比为:55.29:7.75:1.99:1.13:1;相对分子质量约为568万;红外光谱中有β-糖苷键的特征吸收峰;紫外扫描有蛋白质的特征吸收峰.桃胶多糖为一种蛋白质复合多糖.     

蛹虫草固体发酵培养基多糖的分离纯化及组成分析

为研究蛹虫草固体发酵培养基中多糖的分离纯化及组成,本实验利用水提醇沉法与Sevage法相结合,得到蛹虫草固体发酵培养基粗多糖(CMSMP).经DEAE-cellulose 52柱层析分离得到纯化蛹虫草固体发酵培养基多糖组分(CMSMPI)后,采用紫外光谱、醋酸纤维素薄膜电泳和Sephadex G-150凝胶柱层析鉴定其纯度,高效液相色谱及红外光谱分析其组成、结构.结果表明,CMMSP1为均一多糖,且由木糖、阿拉伯糖和葡萄糖三种单糖组成.同时红外光谱显示,CMSMP1具有典型多糖吸收峰.     

草菇多糖VVP-1b的分离纯化及其光谱分析

从草菇子实体中提取水溶性粗多糖,经脱蛋白、脱色、DEAE-Sepharose F.F和Superdex-200柱层析,分离纯化得到一种水溶性草菇多糖组分VVP-1b。采用液相色谱、紫外光谱、红外光谱等光谱方法对其部分理化性质和结构进行测定。结果表明:VVP-1b为均一组分,具有明显的多糖特征峰,含有β-吡喃糖苷键;其总糖含量、蛋白含量、糖醛酸含量分别为88.7%、7.8%、27.6%,相对分子质量为5.84×105;单糖组成及摩尔比为阿拉伯糖∶甘露糖∶半乳糖∶葡萄糖=4.0∶1.0∶1.4∶35.4。因此VVP-1b是一种均一的具有β-吡喃糖苷键的酸性多糖。     

沙蒿籽胶多糖的分级纯化和结构分析

采用0.1mol/L的氢氧化钾对沙蒿籽胶多糖进行组分分级得到水溶多糖(AG1)和水不溶多糖(AG2)。利用离子交换柱层析从AG1中分离得到酸性多糖(AG11)和中性多糖(AG12)。经凝胶过滤色谱检测,AG11和AG12为均一组分。化学组成分析表明,AG1为葡萄糖糖基组成的葡聚糖,并含有糖醛酸;AG11和AG12分别为阿拉伯糖、鼠李糖、木糖、甘露糖、葡萄糖和半乳糖等糖基组成的杂多糖,并含有糖醛酸,相对分子质量分别为8.63×105Da和3.46×105Da。红外光谱测定表明,AG11、AG12和AG2具有多糖的特征吸收,并且其糖环均为吡喃环。     

白背三七多糖的分离纯化

采用D315弱碱性阴离子交换树脂和Sephadex G-25凝胶柱层析,从白背三七叶粗多糖中分离纯化得到中性多糖GDPs-1、GDPs-2及酸性多糖GDPs-3 3个多糖组分。经高效凝胶色谱测定,重均分子质量分别为：1.06×104、4.17×103D和3.74×103D;纯度分别为94.08%、92.3%和99.8%。红外光谱证明3种多糖均含有多糖类特征吸收峰,初步推测GDPs-1中α和β构型并存,GDPs-2和GDPs-3为α构型;核磁共振结果进一步证实3种多糖中均只含有α构型。     

海带中褐藻糖胶LPS-B的分离纯化与分析

海带中的褐藻糖胶经离子交换纤维素层析得到了4种亚组分:LPS-A、LPS-B、LPS-C、LPS-D,并用凝胶介质对其中的一种主要组分(LPS-B)进行进一步的分离纯化,最终得到两种均一多糖(PB-1和PB-21),高效凝胶过滤色谱法(HPGPC)测定分子量。结果表明,PB-1的Mw=5.64×105,Mn=2.97×105,分散度D=1.89;PB-21的Mw=3.54×104,Mn=2.46×104,分散度D=1.44。红外光谱分析表明,所得的两种均一多糖具有多糖的红外吸收峰,且都不含有糖醛酸。     

梭柄松苞菇多糖CVP-Ⅱ_2的理化性质及其结构研究

以梭柄松苞菇子实体为原料,采用超声辅助水提醇沉法,经脱色、脱蛋白、DEAE-52离子交换柱层析、葡聚糖凝胶Sephadex G-100柱层析分离纯化得到梭柄松苞菇多糖CVP-Ⅱ2,用高效凝胶渗透色谱(GPC)结合葡聚糖凝胶Sephadex G-100的分离结果鉴定其分子量分布及纯度,利用碘-碘化钾、苯酚-硫酸法、考马斯亮蓝G-250法、硫酸-咔唑法对其淀粉含量、总糖含量、蛋白含量、糖醛酸含量进行测定;经紫外光谱分析、红外光谱分析、GC分析其官能团特征及单糖组成。结果表明,CVP-Ⅱ2为非淀粉白色絮状均一多糖,其总糖、蛋白质含量、糖醛酸含量分别为:总糖含量为86.76%,不含蛋白质,糖醛酸含量为12.93%;其重均相对分子量Mw为11252u;红外光谱显示CVP-Ⅱ2具有多糖的特征吸收峰且为吡喃型糖环构型;单糖组成结果显示CVP-Ⅱ2含岩藻糖、甘露糖、葡萄糖和半乳糖,其摩尔比为:甘露糖∶岩藻糖∶葡萄糖∶半乳糖=1∶1.63∶29.36∶5.02。     

金针菇子实体多糖均一组分FVP60-C2制备及单糖组成分析

金针菇子实体经水提醇沉得水溶性粗多糖,再经DEAE-Sepharose Fast Flow离子交换柱和凝胶柱层析纯化,得到均一多糖FVP60-C2;采用高效液相色谱、紫外-可见光光谱全扫描和傅里叶变换红外光谱研究其理化性质;样品经三氟乙酸水解,乙酰衍生化后,用单糖标准品作对照,用气相色谱分析其单糖组成。结果表明:FVP60-C2为均一多糖,平均分子质量为1.429×104D;其是由岩藻糖、木糖、甘露糖、葡萄糖和半乳糖组成的杂多糖,各单糖的物质的量比为0.74:0.21:1.36:1.00:1.31。     

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