食品中油脂提取及过氧化值检测方法的优化

以耐贮面包为原料,分别对食品中油脂提取和过氧化值检测方法进行单因素优化。实验以GB2003为基础,选取石油醚添加量,旋蒸时间,干燥时间为影响油脂提取的主要因素,选取油脂取样量,有机溶剂比例和体积,饱和碘化钾添加量,反应时间,蒸馏水添加量,淀粉指示剂浓度和滴定溶液浓度为影响过氧化值检测精度因素,依次进行优化。结果表明,样品中油脂最佳提取条件为：添加石油醚体积为面包质量的1.2倍（mL/g）,提取14～18h,用旋转蒸发器旋蒸15min,在50℃鼓风干燥箱中挥发石油醚1h得油脂样本;过氧化值检测的最佳条件为：取油脂3.00～5.00g,加入三氯甲烷与冰乙酸溶液（V∶V=2∶3）30mL,饱和碘化钾1.5mL,暗处反应3min,加入蒸馏水80mL,10g/L淀粉指示剂1mL,用0.002mol/L硫代硫酸钠标液滴定。此条件下,提取得到的油脂较纯,过氧化值检测灵敏度提高,最低检测值为0.001g/100g,精密度较好。     

聚氯乙烯类食品包装材料中三甲基锡向食品模拟物的迁移规律

目的：建立聚氯乙烯类包装材料和食品模拟物中三甲基锡的超高效液相色谱-串联质谱（ultra performanceliquid chromatography-tandem mass spectrometry,UPLC-MS/MS）联用测定方法。用该方法研究聚氯乙烯中的三甲基锡向食品模拟物的迁移规律。方法：聚氯乙烯包装材料样品用乙酸乙酯提取。食品模拟物经阳离子固相萃取柱净化富集,洗脱液水浴条件下氮气吹干,残渣用流动相溶解,旋涡混匀,过0.22 μm微孔滤膜,经C18色谱柱完成分离,MS/MS仪上采用多反应监测正离子模式测定三甲基锡,外标法定量。在设定的不同温度条件下,将聚氯乙烯包装材料浸泡于食品模拟物中,于不同的时间点移取浸泡液,经前处理后测定三甲基锡迁移量。结果：三甲基锡在0.1～100.0 μg/L范围内线性关系良好（相关系数r=0.999 8）,检出限为0.02 μg/L。在1.0、10.0、50.0 μg/L 3 个添加水平范围内的平均回收率为90.6%～97.3%,相对标准偏差不高于6.9%。测定结果显示,三甲基锡迁移量在水模拟物中为0.19～1.65 μg/L、在体积分数10%乙醇模拟物中为0.19～9.89 μg/L、在3 g/100 mL乙酸模拟物中为0.11～9.96 μg/L、在正己烷模拟物中为0.15～3.54 μg/L。结论：建立的阳离子固相萃取-UPLC-MS/MS联用法测定食品模拟物中三甲基锡的方法快速简单、准确有效,三甲基锡在体积分数10%乙醇溶液和3 g/100 mL乙酸溶液迁移量较高,且随温度升高、时间延长,迁移量增加,一定时间后达到迁移平衡。     

中式油炸食品中丙烯酰胺测定及降低方法初探

研究高效液相色谱法分析测定中式油炸食品中丙烯酰胺方法。样品预处理条件:油炸样品粉碎后用0.1%甲酸水溶液(料液比1:5)进行三次重复提取,提取液经高速离心、冷冻、C_(18)固相萃取小柱纯化,最后采用高效液相色谱仪进行测定。测定色谱条件:流动相为甲醇—0.02 mol/L乙酸胺溶液(5:95,v/v)、流速为0.9 ml/min、进样量为20μl、保留时间约4.887 min,检测器为紫外检测器,波长为210 nm、柱温25℃±0.5℃;试验结果表明,丙烯酰胺色谱图峰面积与其浓度在0.5～5.0μg/mL范围内呈良好线性关系,其最低检出限为10 ng/mL,回收率为94.5%～106.5%,相对标准偏差3.2%～4.5%;该法回收率高、精密度好,重复性好。利用该法测定几类市售中式油炸食品和自制油炸食品中丙烯酰胺含量,结果表明,市售中式油炸食品丙烯酰胺检出率为100%,仅含量水平有较大差异;试验也表明,通过优化工艺技术条件和配方如调节pH值或添加抗氧化剂等可降低油炸食品中丙烯酰胺含量。     

特异性定量测定油脂和含油食品酸价的新铜皂比色法

建立了一种可特异性测定食用油脂及含油食品中游离脂肪酸（FFA）的新铜皂比色法。优化了铜皂比色法的最佳测定波长,研究了有机相溶剂对显色强度和油脂溶解稳定性的影响,以及不同种类FFA对铜皂反应显色强度的影响。此外,研究了食用油脂样液水洗、酸性食品添加剂和酸性食用香精香料对铜皂比色法测定的影响。结果表明：新铜皂比色法的最佳测定波长为710 nm,环己烷是理想的有机相溶剂;新铜皂比色法能有效排除酸性食品添加剂等非FFA的酸性物质干扰;该法采用油酸显色,外标法定量,可实现0.1~5.0 mg/g的液态油和0.2~10.0 mg/g的固态脂酸价的定量测定;对于无酸性物干扰的食用油脂,其测定结果与传统酸碱滴定法相关性良好（R2>0996）,回收率为91.3%~93.8%,重复性实验相对标准偏差小于3%,单次测定仅需1 g油脂样品。因此,新铜皂比色法是一种准确而便捷的酸价测定技术,适用于油脂和含油食品的酸价测定。     

基于微孔板比色法的微生物胞内油脂快速检测方法的建立及应用

对磷酸香草醛显色法的反应条件进行优化研究,建立了磷酸香草醛显色法快速检测微生物胞内油脂的方法,并探讨该方法在微生物油脂测定上的应用.经过实验确定最佳比色条件为:将油脂样品蒸干溶剂后加入2 mL 98％硫酸,于90℃水浴20 min,冷却至室温后添加3 mL 0.25 g/L香草醛磷酸溶液(34％的磷酸溶液配制),摇匀室温显色20 min,扣除非油脂成分干扰,在530 nm波长下测定吸光度,经验证该反应体系稳定性良好.在裂殖壶茵和隐甲藻两种产DHA油脂微生物中,通过称重法与磷酸香草醛显色法比较,进一步证实建立的方法分析结果准确可靠,分析过程简便、快速,稳定性好,适合作为常规分析检测方法.     

固相萃取-高效液相色谱法检测油炸猪肉中丙烯酰胺

建立油炸猪肉中丙烯酰胺的固相萃取-高效液相色谱检测方法。油炸猪肉样品经正己烷脱脂,2 mol/L氯化钠溶液提取,乙酸乙酯萃取,固相萃取小柱净化后,以甲醇-水（5∶95,v/v）为流动相,Hypersi10DS2-C18色谱柱分离,内标法定性、定量分析丙烯酰胺。结果表明：丙烯酰胺的定性检出限为6 μg/kg,定量检出限为20 μg/kg,线性定量范围0.05～1.00 μg/mL,线性相关系数（R2）为0.999 8,本方法的加标回收率稳定在90%～92%范围,相对标准偏差小于3.5%。     

不同基质食品中乌洛托品残留量的检测方法研究

目的建立适用于猪肉、豆干、豆腐、腐竹基质中乌洛托品的分析检测方法。方法比较提取方式、浓缩温度、固相萃取柱、微孔滤膜等关键因素测定样品中乌洛托品,样品用乙腈超声提取,35℃旋蒸浓缩,经cleanert PCX固相萃取柱及0.22μm亲水PTFE微孔滤膜净化,高效液相色谱串联质谱仪进行检测。结果乌洛托品在5~500μg/L质量浓度范围内线性相关系数为0.9997;添加水平为1~50μg/kg时,平均回收率为75.7%~91.9%,相对标准偏差为1.10%~9.88%。结论该方法快速、准确度和精密度均能满足日常检测的需求。     

固相萃取/ 固相微萃取- 气相色谱法测定饮用水中多溴联苯醚

目的：建立固相萃取/固相微萃取-气相色谱法测定饮用水中多溴联苯醚(BDE-47和BDE-99)含量的新方法。方法：固相萃取-气相色谱直接取水样100mL,过LC-C18柱,经正己烷洗脱,洗脱液于80℃水浴挥干,异辛烷定容至1mL,直接进样1μL测定,该法对BDE-47和BDE-99的检出限分别为0.0008μg/L和0.0009μg/L,回归方程相关系数分别为0.9996和0.9997,RSD(n＝6)分别为1.0%～4.9%和0.96%～4.4%;固相微萃取-气相色谱直接取水样10mL置于15mL固相微萃取瓶中,于40℃条件下固相微萃取吸附25min后,纤维头经风干,立即进样测定。该法对BDE-47和BDE-99的检出限分别为0.0000μg/L和0.0044μg/L,回归方程相关系数分别为0.9996和0.9992,RSD(n＝6)分别为6.7%～11.4%和6.0%～10.1%。结果：随机抽样某市52个水样进行检测,均未检出BDE-47和BDE-99。结论：建立饮用水中多溴联苯醚固相萃取/固相微萃取-气相色谱检测的新方法,两种方法操作简便、快速,精密度、准确度及回收率均令人满意。     

SPE-HPLC-ESI-MS-MS测定常见焙烤及油炸食品中丙烯酰胺的含量

目的：建立一种焙烤和油炸食品中丙烯酰胺的固相萃取-高效液相色谱-电喷雾离子化串联质谱检测方法。方法：样品用水提取,Cleanert SLE固相萃取柱净化,高效液相色谱-电喷雾离子化串联质谱测定,内标法定量。结果：在0.01～3.00 mg/L范围内,线性相关系数大于0.998,方法的检出限为1.0 μg/kg。在3 个添加量（10、100、1 000 μg/kg）的平均回收率为96.8%,相对标准偏差为2.7%。结论：该方法简便、准确、稳定,已实际应用于测定焙烤和油炸食品中丙烯酰胺的含量。     

油炸过程中3种植物油脂肪酸组分含量及品质的变化

为研究油炸过程中大豆油、山茶油、棕榈油品质的变化,用国标法测定酸价和过氧化值,并利用高极性色谱柱CP-Sil 88对植物油中脂肪酸,特别是反式脂肪酸(TFA)组分和含量的变化进行分析。结果表明:顺式亚油酸(53.06%)、顺式油酸(82.26%)、棕榈酸(49.7%)分别是大豆油、山茶油、棕榈油中主要的脂肪酸。大豆油、棕榈油低温油炸时油脂中总TFA含量不会存在明显变化,平均为15.51mg/g和1.35mg/g。随着油炸时间延长,山茶油中反式油酸含量增加了63.82%。油炸过程中,3种植物油的酸价由高到低依次为山茶油>棕榈油>大豆油,大豆油和棕榈油的过氧化值先增大后减小。在8h连续使用时间内,酸价和过氧化值都未超过煎炸油的卫生标准。综合以上结果,棕榈油中总TFA含量最低,更适合于短时间循环使用的食品加工过程。     

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.