啤酒中嘌呤类物质的测定研究

建立了高效液相色谱法测定啤酒中嘌呤类物质含量的分析方法.啤酒中的嘌吟类物质经高氯酸水解成嘌呤碱,其优化水解条件为:啤酒:高氯酸为1:1,100℃水解30min.优化色谱条件为:采用EclipseXDB-C18反相色谱柱,以0.02mol/L的KH2PO4-H3PO4的缓冲溶液(pH4.00)为流动相,流速1.0mL/min,检测紫外波长为210.4nm,柱温为25℃.结果表明.在优化的色谱条件下,4种嘌呤碱的平均加标回收率为92.91%～102.48%,方法精密度为4.51%～5.47%.该方法的灵敏度高、操作简便、快速,能够满足啤酒中嘌呤类物质的高灵敏分析.     

浊点萃取与液相色谱联用检测啤酒中的黄腐酚

本研究建立了一种浊点萃取（CPE）与高效液相色谱紫外检测联用检测啤酒中黄腐酚的方法。选择非离子表面活性剂Triton X-114作为萃取媒介。对影响CPE的参数进行了评价和优化。当Triton X-114（v／v）浓度为2．5％,pH5．0,NaCl浓度15％（w／v）,平衡温度70℃,平衡时间10min时,黄腐酚的萃取率最高。在此条件下,黄腐酚的检测限为0．003mg／L。日内和日间精密度均以相对标准偏差表示,分别为4．6％和6．3％。此方法可成功用于检测各种啤酒样品中的黄腐酚含量。啤酒样品中的黄腐酚含量变化范围为0．052～0．628mg／L,回收率范围为90．7％～101．9％。此种萃取和检测啤酒中黄腐酚的方法效率高、经济环保、成本较低。     

酶制剂及PVPP等添加剂在啤酒生产中的应用

选用绿色食品稳定剂来降低麦汁中的多酚含量。采用均匀设计法对啤酒发酵过程中绿色食品稳定剂的添加量进行优化。选取α-淀粉酶、糖化复合酶、木聚糖酶、单宁、硅胶、麦汁澄清剂和PVPP作为参试因子，按照均匀设计U12（12^10）的方案进行试验，以色度为目标函数（y）对数据进行二次回归分析，得出最优组合为：单宁59．269mg／kg，PVPP357．384mg／kg，硅胶237．214mg／kg，麦汁澄清剂78．991mg／kg，α-淀粉酶1．100mL／kg，糖化复合酶3．300mL／kg，木聚糖酶0．550mL／kg。该优化工艺发酵的啤酒多酚值为101．78mg／L；总氮、色度、pH、总酸、酒精度、双乙酰、CO2与所测的珠江啤酒的指标接近。     

高效液相色谱法测定糖蜜中的甜菜碱含量

建立了一种简单、快速测定甜菜糖蜜中甜菜碱的方法,即样品经去离子水提取,碱式醋酸铅脱色后,采用高效液相色谱-DAD检测器测定甜菜碱的含量。色谱柱为AgilentZorbaxNH2柱（Φ4．6mm×150mm,5Ixm）,流动相为0．05mol／L KH2PO4溶液（pH=4．53）,流速0．7mL／min,柱温30℃,检测波长195nm。试验结果表明：甜菜碱在0．1mg／mL～5．0mg／mL范围内线性良好,相关系数为0．998;加标回收率为99．5％～99．7％,相对标准偏差（RSD）为0．09％-1．06％（n=3）。     

单克隆免疫亲和柱—高效液相色谱法测定啤酒中伏马毒素B1、B2

研究了单克隆免疫亲和柱－高效液相色谱法测定啤酒中伏马毒素B1、B2的方法。啤酒样品经脱气后,通过FumoniTest免疫亲和柱净化,净化液经柱前衍生,Spherisorb C18色谱柱分离,荧光检测器检测,外标法定量。对添加不同含量水平的伏马毒素B1、B2,5次重复实验的平均回收率为B1 86．1％－93．4％,B2 71．6％－82．0％。变异系数（CV）为B1 4．8％－7．2％,B2 6．3％－8．9％。检测低限为B1 0．005mg/kg,B2 0.01mg/kg。     

复方二氯醋酸二异丙胺氯化钠注射液中二氯醋酸二异丙胺的HPLC测定

目的建立HPLC法测定复方二氯醋酸二异丙胺氯化钠注射液中二氯醋酸二异丙胺的含量。方法用十八烷基硅烷键合硅胶柱，流动相为高氯酸水溶液（0．82mL高氯酸稀释至1000mL，加三乙胺2mL，磷酸调pH3．0）-乙腩（97：3），检测波长215nm，流速1．0mL／min。结果二氯醋酸二异丙胺在0．48～1．12mg／mL范围内线性关系良好，平均回收率为100．3％，RSD为0．37％。结论此法简便、准确，可用于复方二氯醋酸二异丙胺氯化钠注射液的质量控制。     

灵芝深层发酵中麦角甾醇含量的测定

利用HPLC法研究了灵芝真菌发酵过程中胞内外麦角固醇的含量,经紫外全波长扫描,确定测定波长为282mm,研究表明：此方法测定麦角固醇含量最大标准偏差为O．92％,得到线性回归方程为y=28685x-382．61（R=0．9998）,该回归方程在20～500嵋的范围内。精密度试验,灵芝真菌发酵胞内外麦角固醇含量RsD分别为O．40％和1．96％,说明此试验设计条件精密度良好,经加标后,麦角固醇的回收率在96．82～102．50％之间,表明此方法用于测定灵芝真菌发酵过程中麦角固醇含量准确、可行,经测定灵芝真菌发酵至120h,麦角固醇含量增至最高,胞内含量达到O．64mg／g,胞外含量达到0．07mg／mL。     

乙酰丙酮衍生——液相色谱法测定啤酒中的甲醛含量

采用乙酰丙酮衍生，以高效液相色谱法测定啤酒中甲醛的含量。样品无需蒸馏．添加衍生试剂后在50℃保温20min即可供分析。色谱柱为Agilent ZORBAX SB-C18，流动相为乙腈，水（20，80），测定波长为412mm，采用标准加入法定量，在0—2．28mg/L范围内呈良好的线性，方法检出限为95μg／L．样品测定的RSD为1．0％-5．7％。本法具有灵敏度高，操作简捷，测定结果可靠等特点。除了优化测定条件的试验外，还对国内外22种品牌啤酒的甲醛含量作了测定。     

HPLC法测定糖蜜中的棉籽糖

建立了一种简单、快速测定甜菜糖蜜中棉籽糖的方法。即样品经超声波提取,碱式醋酸铅脱色净化后,采用高效液相色谱-RID检测器直接测定糖蜜中的棉籽糖含量。色谱条件：色谱柱为Agilent Zorbax carbohydrate柱（4．6×250mm,5μm）,流动相为乙腈-水（75：25,V：V）,流速lmL／min,柱温30℃（2,RID检测。试验结果表明：棉籽糖在0．5mg／mL-10mg／mL范围内线性良好,相关系数为0．9999;加标回收率为89．7％～102．6％,相对标准偏差（RSD）为1．67％-4．36％（n=3）。     

啤酒中有机酸含量的RP-HPLC检测条件优化及其酿造过程中动态分析

该研究对反相高效液相色谱（RP-HPLC）法测定啤酒中有机酸含量的方法进行优化,最终确定了RP-HPLC法测定啤酒中草酸、乳酸、酒石酸、乙酸、苹果酸、α-酮戊二酸、抗坏血酸、柠檬酸、琥珀酸9种有机酸的检测条件,并结合发酵机理对啤酒酿造过程中的有机酸含量动态变化进行分析。结果表明,RP-HPLC优化条件为：检测波长215 nm、流动相缓冲液0.10 mol/L KH2PO4、pH值3.0、流速0.6 mL/min。有机酸在质量浓度0.2～400.0 mg/L范围内线性关系良好（R2均＞0.99）,加标回收率79.3%～110.0%,精密度试验结果相对标准偏差（RSD）为0.3%～11.5%,表明该方法精密度高、准确性良好。在啤酒酿造过程中有机酸总量及乙酸、琥珀酸、苹果酸、乳酸、柠檬酸、α-酮戊二酸含量呈现先增长后平稳的趋势,草酸、抗坏血酸、酒石酸含量变化相对平稳。     

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