高压液相色谱法测定食品接触材料水性模拟液中2,4-二羟基二苯甲酮

目的 探讨高压液相色谱法测定食品接触材料水性模拟液中2,4-二羟基二苯甲酮的方法。方法 食品接触材料经水、10%乙醇(v/v)、20%乙醇(v/v)、50%乙醇(v/v)以及3%乙酸(w/v)5种不同水性模拟液提取后, 以Agilent HC-CN为分析柱, 甲醇: 水(55: 45, v/v)为流动相, 经UV检测器(?=290 nm) 进行定量分析。结果 5种不同水性模拟液中2,4-二羟基二苯甲酮在0.5~10.0 mg/L浓度范围内线性关系均良好(r=0.9999), 检测限(S/N=3)均为0.02 mg/L。在低、中、高3个不同添加水平下进行加标回收实验, 2,4-二羟基二苯甲酮的平均回收率为84.0%~96.9%, RSD(n=6)为0.85%~4.60%。结论 本方法简单、快速、准确, 完全能够满足食品接触材料日常检验的需要。     

TLC法测定烟叶中茄尼醇的含量

本文建立了烟叶茄尼醇含量测定的薄层扫描分析方法；以硅胶G为薄层吸附剂，石油醚-乙酸乙酯（4：1，v／v）为展开剂，香草醛-硫酸-乙醇液显色，在620nm处进行扫描测定，茄尼醇质量在2．04ug～7．68ug范围内，与峰面积呈良好的线性关系C=349．94S-193．94，r=0．9954，RSD为6．86％（C为茄尼醇浓度ug／ml，S为峰面积）。并对烟的烟叶、嫩芽、茎进行了含量测定。结果表明：用TLC法测定烟叶中茄尼醇的含量方法简便、快捷、准确度高、重复性好。烟叶中茄尼醇含量达0．822％。     

生物催化合成熊果苷的微生物的筛选研究

以麦芽糖和蔗糖为葡萄糖基供体检测了67株包括丝状真菌、酵母菌和细菌在内的微生物催化合成熊果苷的能力,采用高效液相色谱法测定转化液中熊果苷的含量,利用质谱法和比旋光度测定法分析产物的分子量和构型.结果表明催化合成熊果苷的能力在微生物中是很普遍的,被检测的微生物中70%以上能不同程度催化合成熊果苷,大多数微生物合成的为β-熊果苷,少数微生物合成的为α-熊果苷.     

苹果浓缩汁加工中香气回收成分分析

以同一苹果浓缩汁生产线上收集的300倍回收香精、预浓缩回收液水和浓缩回收液水为实验材料,分析了三个样品中香气物质成分,旨在确定苹果浓缩汁加工过程中香气物质的变化特性和浓缩回收冷凝水中香气物质的主要成分。顶空固相微萃取结合气质联用测定各样品香气成分的差异,共检测出47种香气成分。结果表明:a.300倍回收香精中富含酯类、醛类、醇类香气物质,苹果浓缩汁预浓缩过程中,香精回收工艺收集了主要的芳香酯类(乙酸-2-甲基-1-丁酯、乙酸-2-苯基乙酯、乙酸乙酯等)和醛类[(E)-2-己烯醛、苯甲醛等]香气物质,芳香醇类香气物质相对较少。b.苹果汁预浓缩回收液水中苹果的典型醇类(1-己醇41.70%)香气物质含量高且丰富,同时预浓缩回收液水含有较高相对含量枯焦气息的苯酚类化合物(2,5-二叔丁基-对甲基苯酚13.26%、2,4-二叔丁基苯酚11.16%)。c.苹果汁浓缩回收液水富含苹果典型酯类香气物质(乙酸-2-甲基-1-丁酯、乙酸丁酯、乙酸甲酯等)和醇类香气物质(2-甲基-1-丁醇等),由加工过程中苹果汁中香气物质进一步逸散产生。     

葡萄籽原花青素的分离纯化及其自由基淬灭活性的研究（上）

葡萄籽经有机溶剂梯度法及酶法提取，大孔树脂初步纯化，薄层色谱法分离纯化得到原花青素单体和二聚体。结果表明，以60％醇于50℃浸提3次、每次30min（固液比1：7，w／v）效果最好；梯度提取各细分原花青素得率为：（7．73-281．49）mg／100g葡萄籽，其中以乙酸乙酯组分最高，其次为丙酮、乙醇、乙醚。在浓度为0．004g／mL时，淬灭自由基活性最高的是乙醇组分，抑制率为85．13％，其次是乙醚（77．60％）和乙酸乙酯组分（48．64％）。大孔树脂纯化以40％乙醇最佳。以制备薄层法（展开体系：v甲苯：v丙酮：v冰乙酸=2：2：1）分别对乙酸乙酯、乙醚组分进行纯化，前者原花青素单体和二聚体的百分含量分别为33．25％和16．23％，后者为60．64％和10．13％．     

美洲种葡萄Conquister干红葡萄酒香气的GC／MS分析

采用液-液萃取法提取美洲种葡萄Conquister葡萄果汁和干红葡萄酒中的香气成分,应用色谱面积归一法测定各成分的相对含量。结果表明,从美洲种葡萄Conquister葡萄汁中共鉴定出68种香气成分,相对含量较高的分别为乙酸乙酯、5-羟甲基-2-呋喃甲醛、2,3-二氢-3,5-二羟基-6-甲基-4(H)吡喃-4-酮、乙酸、(E)-2-己烯-1-醇、1-己醇、乙酸异丙酯、糠醛、2-丁烯酸乙酯、乙醇等;从干红葡萄酒中共鉴定出68种香气成分,相对含量较高的分别为乙醇、异戊醇、乙酸异戊酯、苯乙醇、辛酸乙酯、乙酸乙酯、葵酸乙酯、辛酸、7-[2-(乙酰基)-3à,5á-二甲氧基环戊基-1]-己酸乙酯、1-己醇。     

高效液相-紫外法检测三孢布拉霉菌发酵液中2-氨基-6-甲基吡啶

建立高效液相色谱-紫外法对三孢布拉霉菌发酵液中2-氨基-6-甲基吡啶含量检测的方法。采用AlltimaC18(250mm×4.6mmi.d.,5μm)色谱柱,以甲醇:水:1%乙酸=85:10:5(v/v/v)为流动相,流速为1.0mL/min时,2-氨基-6-甲基吡啶及其他杂质得到良好分离,紫外光谱231nm检测。在该色谱条件下,2-氨基-6-甲基吡啶浓度5～500mg/L时,其峰面积与相应的浓度线性关系良好(R2=0.9994),回收率99.76%～101.4%,精密度RSD<2.17%。该方法简便、快速、准确可靠,为三孢布拉霉菌发酵液中2-氨基-6-甲基吡啶的检测和含量控制提供了可靠的分析方法。     

氯化铵对苹果白兰地挥发性香气成分的影响

采用顶空固相微萃取-气相色谱-质谱联用技术分析添加氯化铵及无添加对照发酵苹果白兰地酒中的香气成分.经分析鉴定：在苹果白兰地的挥发性物质中,酯类和醇类相对含量较高,构成了苹果白兰地的主要香气成分;苹果白兰地发酵中添加氯化铵有助于提高主要酯类物质的相对含量,其中相对含量较高的香气物质为：乙酸乙酯、3-甲基-乙酸-1-丁酯、乙酸己酯、己酸乙酯、辛酸乙酯、癸酸乙酯、3-甲基-1-丁醇和乙醇等.     

免疫亲和柱-液相色谱法快速测定面粉中黄曲霉毒素B_1的条件优化

建立了免疫亲和柱-液相色谱法快速测定面粉中黄曲霉毒素B_1的方法。样品经甲醇-水(80:20,v/v)提取,经过滤、沉淀(乙酸锌和亚铁氰化钾),通过免疫亲和柱净化,三氟乙酸和正己烷为衍生剂进行衍生,采用C_(18)柱为分离柱,乙腈:水(50:50,v/v)为流动相进行高效液相色谱分离分析。实验结果表明,黄曲霉毒素B_1线性范围(1~10)ng/m L,R2=0.9991,RSD=3.4%,检出限为0.1μg/kg,实际样品的黄曲霉毒素B_1回收率为81%~95%。该方法具有灵敏度高、回收率高、重现性好等优点,可用于面粉中黄曲霉毒素B_1的快速测定。     

HPLC法测定大豆提取物中大豆异黄酮含量的研究

主要建立了HPLC法测定大豆提取物中大豆异黄酮含量的方法。通过实验确定了HPLC法测定大豆提取物中大豆异黄酮的最佳条件是：采用Waters Symmetry5μmC18,250mm×4．6mm色谱柱;流速：1．0mL／min;波长260nm;柱温：35℃;流动相A为含0．1％（v/v）乙酸的乙腈溶液,流动相B为含0．1％（v／v）乙酸的超纯水溶液,流动相梯度：18％-35％N乙腈溶液。该方法灵敏度高、重现性好,回收率达98％,变异系数小于3％,为研究大豆异黄酮其它产品打下了良好的基础,操作方法简单,易于掌握。     

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