高效体积排阻色谱测定油脂中氧化甘油三酯聚合物

为了分析甘油三酯氧化产物——氧化甘油三酯及其聚合物的组分分布,研究了高效体积排阻色谱检测高相对分子质量聚合物的方法,建立了采用正相硅胶制备色谱预分离油脂中极性组分,极性组分以高效体积排阻色谱-示差折光检测器测定,标准相对分子质量聚苯乙烯定性,峰面积归一化法定量的检测方法.油脂中极性组分的典型色谱峰构成是:氧化甘油三酯寡聚合体、氧化甘油三酯二聚体、氧化甘油三酯单体、甘油二酯、游离脂肪酸等.以氧化甘油三酯聚合物鉴别地沟油等深度氧化劣变食用油具有良好的应用前景.     

煎炸不同食材的花生油中极性组分与氧化甘三酯聚合物含量的相关性研究

利用花生油分别对油条、薯条、鸡翅、豆腐4种食材进行32 h连续煎炸,对每隔2 h所取煎炸油样进行极性组分、氧化甘三酯聚合物含量的检测,并与不加任何食材的空白煎炸油脂进行对比,分析研究花生油连续煎炸不同食材过程中极性组分、氧化甘三酯聚合物及其他指标的综合变化。结果表明:随煎炸时间的延长,煎炸油中极性组分、氧化甘三酯聚合物含量升高,煎炸油酸值升高、色泽加深,反式脂肪酸含量升高,经32 h连续深度煎炸,油条、薯条、鸡翅、豆腐、空白5种煎炸油中极性组分从初始的3.34%分别增至32.98%、30.61%、15.50%、29%、47.02%,其中油条、薯条、鸡翅、空白煎炸油中极性组分含量分别在32、24、30、16 h时超出27%的国标限量。氧化甘油三酯聚合物含量从初始的0.43%分别增至18.97%、23.68%、6.52%、16.92%、38.83%。煎炸油中极性组分与氧化甘油三酯聚合物含量间存在极显著的线性相关(P0.01),R2分别为0.996 4、0.993 7、0.9972、0.974 0、0.991 2。经32 h连续煎炸,5种煎炸油的酸值从初始的0.17 (mgKOH/g)的分别增至7.15、2.24、2.39、2.75、2.18(mg KOH/g);反式酸含量从初始的0.17%增加至0.34%、0.28%、0.39%、0.38%、3.54%。     

氧化甘三酯指标在煎炸油品质评价中的应用（网络首发、推荐阅读）

研究煎炸过程油脂各极性组分的变化规律,并从法定废弃点处极性物质组成及指标间相关性两个角度,评价各极性组分指标用于表征油脂煎炸废弃的可行性。煎炸过程,油脂劣变生成的总极性组分(TPC)随煎炸时间的延长而累积。在油脂法定废弃点处,当TPC为27%时,煎炸油脂含11.2%的氧化甘油三酯多聚物+氧化甘油三酯二聚物(oxTGO+oxTGD),与各国标准规定的TPC和ox TGO+oxTGD比例是接近的。当TPC为27%时,煎炸油脂的氧化甘油三酯单体(ox TGM)含量为3.5%,煎炸过程oxTGM含量变化呈上下波动而无明显规律。Pearson相关性分析表明,煎炸过程油脂oxTGM与TPC无显著相关(P>0.05),表明应用TPC评价煎炸油品质时,实际未能同时覆盖对oxTGM的有效控制。因此须用TPC和oxTGM两项指标方可评价油脂煎炸过程的劣变。考虑到oxTGM的潜在毒性最强,oxTGM值作为表征高温煎炸油脂氧化劣变的废弃指标有一定实际意义。     

HPSEC法测定食用棕榈油中氧化甘油三酯聚合物

试验采用制备型快速柱层析-高效体积排阻色谱(HPSEC),先通过制备型快速柱层析技术,将食用棕榈油中的极性组分提取出来。再采用高效体积排阻凝胶色谱对极性组分进行色谱分离分析,以甘油三酯为标准,凡是在甘油三酯之前分离的物质为油脂的氧化甘油三酯聚合物,最后采用峰面积归一化法计算出氧化甘油三酯聚合物在极性组分中的含量,再根据极性组分在全油中的含量,计算出全油中氧化甘油三酯聚合物的含量。结果表明:该方法检出限为0.000 1%,标准品易购得,检测数据稳定、准确,RSD10%。该方法能满足食用棕榈油的检测要求。     

不同类别甘油二酯型煎炸油对油条品质的影响研究

以40%与80%甘油二酯含量的大豆油基甘油二酯油和橄榄油基甘油二酯油作为油条煎炸用油，通过测定油条比容、质构特性、含油率以及感官评分，探究不同类型甘油二酯油对煎炸油条品质的影响。结果表明：40%和80%甘油二酯含量的大豆油基甘油二酯油、橄榄油基甘油二酯油制得的油条与市售普通大豆油、橄榄油制得油条在比容、质构方面均无明显差异。在含油率检测中，80%甘油二酯含量的大豆油基甘油二酯油制得油条的含油率显著降低(17.81%)。在感官评分中，2种类型的甘油二酯油制得油条的感官得分均高于普通煎炸油所炸取油条。对比不同煎炸油及其加工条件，获得油条最佳煎炸条件为：80%甘油二酯含量的大豆油基甘油二酯油、煎炸温度180℃、煎炸时间70 s，以及80%甘油二酯含量的橄榄油基甘油二酯油、煎炸温度200℃、煎炸时间60 s。研究表明，在最佳煎炸条件下，不同类型甘油二酯油作为煎炸用油既可以提高油条的口感和品质，还可同步改善摄入油脂的健康水平。     

油炸豆制品中极性组分含量的检测研究

豆制品含有丰富的蛋白质,经高温油炸后,香气宜人,色泽金黄,但在煎炸过程中会产生极性物质。选取上海市三家企业的不同油炸豆制品,研究油炸豆制品中油脂极性组分含量。采用制备型快速柱层析法进行极性组分的检测,并对油炸豆制品中水分含量、油脂含量、油脂极性组分含量以及对应的煎炸油中极性组分含量进行同步测定。结果表明:油炸豆制品中水分含量、油脂含量及油脂极性组分含量与油炸豆制品的生产工艺有关;油炸豆制品中油脂极性组分含量与其煎炸油中极性组分含量相对应;三家企业的三种油炸豆制品中油脂极性组分含量均低于国家限定标准27%,但仍应及时对煎炸油进行净化和更新。     

高效液相双柱法测定油脂中的甘油三酯氧化聚合物

为了建立简便、准确、快速测定油脂中的甘油三酯氧化聚合物(triacylglycerol polymers,TGP)的方法,用正向硅胶柱串联凝胶柱(双柱法),经高效液相色谱-蒸发光散射检测器分离检测油脂中的非极性部分、甘油三酯氧化寡聚物、甘油三酯氧化二聚物(oxidized dimeric triacylglycerols,TGD)、甘油三酯氧化单体、甘油二酯(diacylglycerls,DG)、脂肪酸等极性组分;以DG作为外标,结合外标法和面积归一化法定量油脂中TGP各组分的含量。结果表明:优化的测定条件为石油醚(A)和四氢呋喃(B)为流动相;梯度洗脱程序为0 min、5%B,20 min、15%B,30 min、30%B,35 min、5%B;流速0.7 mL/min;测定时间50 min;该条件下上述各组分分离效果良好。双柱法测定TGP的相关性良好,相关系数(R2)为0.9995,TGD检出限为156 mg/L,定量限为267 mg/L。双柱法对加标DG的回收率在95%~99%之间,相对标准偏差均小于2%;且检测油脂中TGP的重复性良好,相对标准偏差均小于3%。此方法能够在1 h内定量油脂中TGP的含量,操作简便、定量准确、节约试材。     

不同食材煎炸过程极性组分与聚甘油酯变化的研究

利用花生油对油条、薯条、豆腐和鸡翅4种食材分别进行间歇性煎炸(每天早、中、晚各煎炸1 h,连续5 d,累计煎炸15 h),通过对所取油样极性组分(PC)与甘油三酯聚合物(TGP)的检测分析表明,不同食材煎炸过程中PC与TGP均呈明显的增加趋势。4种煎炸油脂的PC值从初始的3.34%分别增加至煎炸结束时的20.29%、23.84%、14.67%和26.27%,TGP值从初始的0.43%分别增加至10.86%、15.29%、5.68%和15.75%,增幅顺序均为鸡翅薯条油条豆腐。煎炸结束时,4种油脂中PC含量均未超出我国标准限量(27%),但煎炸油条、薯条和鸡翅油脂中TGP已达到欧盟国家如比利时和捷克规定≤10%的限量。此外,不同食材煎炸油的PC与TGP均存在着极显著的相关性,即可根据相关性方程通过PC值快速地判断出TGP的大致含量。     

高效体积排阻色谱测定氧化甘油三酯聚合物相对分子质量

通过将油脂的极性组分分离提取后，采用高效体积排阻凝胶色谱技术，以标准相对分子质量的聚苯乙烯为标准对照，对2个精炼餐厨废油脂样品（1个泔水油和1个煎炸老油）的极性组分中氧化甘油三酯二聚物（TGD）、氧化甘油三酯寡聚物（TGO）和氧化甘油三酯（Ox-TG）单体的相对分子质量进行了间接测定,再用三油酸甘油酯标准物质对测定的相对分子质量进行校正，同时考察TGO、TGD与Ox-TG单体的平均相对分子质量（质均）的关系。结果发现：TGD的平均相对分子质量要比Ox-TG单体平均相对分子质量的2倍小80～105，TGO的平均相对分子质量比Ox-TG单体平均相对分子质量的3倍小180～225。     

国内外食物煎炸良好操作规范的实施要点

油炸食品提供了人体所必需的营养成分,但是煎炸油在煎炸过程中容易发生氧化、水解和聚合等反应,产物有害因子,影响煎炸油和煎炸食品的品质。食物煎炸的关键在于过程管理。本文综述了食物煎炸良好操作规范(GMP)6大实施要点,从选择合适的煎炸食用油(饱和度相对高或油脂伴随物丰富)、采用专用的油炸设备、控制油温(煎炸温度不超过190℃)、定期过滤油脂和清洗油炸设备(每天过滤一次)、及时补充新油和定期油品检测(检测极性组分含量的变化)6个方面来阐述如何保障煎炸油和油炸食品的品质。按GMP煎炸操作,即可在保证煎炸食品的营养和安全性,同时延长合格油脂的使用寿命,从而节约食物资源和成本,可为煎炸油国家标准的制订与相关科学研究提供参考。     

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.     

The Ministry of Environmental Protection Issued "Feasible Technology Guidelines for Pollution Prevention and Control in Wood Pulping Process of the Paper Industry (Trial)" and Two Other Guiding Technical Documents

On December 27t＂, 2013, the Ministry of Environmenta Protection announced that, in order to implement ＂The Environmental Protection Law of the People＇ s Republic of China＂, improve the working system in environmenta protection technologies, and promote technologica advancement in pollution prevention, the Ministry of Environmental Protection sponsored the formulation of three guiding technical documents including ＂Feasible Technology Guidelines for Pollution Prevention and Contro n Wood Pulping Process of the Paper Industry （Trial）＂     

1~(st) Intelli-Tissue~ EcoEc Tissue Machine Supplied by PMP Group Successfully Put into Operation in China

正On April 29th,2014,Intelli-Tissue EcoEc tissue machine supplied by PMP Group successfully put into operation at Hebei Xuesong Paper Co.,Ltd.,this is the first such kind of paper machine of PMP Group in China.