食品中山梨酸快速检测方法研究

探讨分光光度法测定食品中山梨酸含量的准确性,为食品安全检测提供高效快速准确的方法。采用分光光度法测定了多种食品中山梨酸含量并进行加标回收率的验证,回收率可达90%~105%。结果证明该方法操作简单、准确性好、速度快、检测成本低。     

紫外分光光度法快速测定调味品中脱氢乙酸含量

目的:本实验建立了紫外分光光度法测定调味品中脱氢乙酸的含量。方法:样品中脱氢乙酸在酸性条件下经水蒸气蒸馏和有机溶剂萃取后,用紫外分光光度计在308nm波长处测定吸光度,与标准比较定量。结果:紫外分光光度法测定调味品中脱氢乙酸加标回收率在94.1%~103.7%之间,RSD为0.4%~4.7%。结论:该方法快速、成本低、操作简便,准确度和精密度高,可应用于生抽酱油、老抽酱油、米醋、蚝油、烧烤汁、甜辣酱等调味品中脱氢乙酸的快速测定。     

黄精提取物中总皂苷含量的测定

采用紫外分光光度法测定黄精提取物中总皂苷的含量并进行方法学考察。结果表明,人参皂苷Re含量在0.033 2～0.298 8mg范围内与吸收度呈良好线性关系,其回归方程为Y=3.229 9 X+0.006 9,相关系数r=0.999 3,总皂苷平均回收率为96.7%,RSD为1.4%。紫外分光光度法测定结果准确可靠,重复性好,可用于黄精提取物中总皂苷的质量控制。     

火焰原子吸收分光光度法测定大豆豆渣中锌的含量

应用火焰原子吸收分光光度法测定大豆豆渣中锌的含量,标准偏差为0.0158,平均回收率为93.0%,方法简便、快速。     

分光光度法和电感耦合等离子体发射光谱法测定面制品中的铝

目的比较分光光度法和电感耦合等离子体发射光谱法测定面制品中的铝含量。方法以GB5009.182-2017《食品安全国家标准食品中铝的测定》第一法-分光光度法和GB 5009.268-2016《食品安全国家标准食品中多元素的测定》第二法-电感耦合等离子体发射光谱法(inductively coupled plasma optical emission spectrometer,ICP-OES)为参照,用2种不同方法对市场上随机抽取的油炸面制品中的铝含量进行检测,同时对2种方法的检出限、精密度和准确度进行比较,通过加标回收率和质控样品来验证2种方法的准确性和可靠性。结果分光光度法的平均加标回收率为95.3%,质控样品偏离真值9.1%;ICP-OES法的平均加标回收率为100.2%,质控样品偏离真值1.6%。结论 ICP-OES法的回收率高于分光光度法,且检出限低,灵敏度高,操作过程简单,能更准确快速的对铝含量进行测定。     

油茶籽饼中茶皂素定量检测方法研究

本文建立了一种快速、简单、准确测定油茶籽饼中茶皂素含量的方法。结果表明:采用分光光度法和高效液相色谱法对同含量的茶皂素测定结果较为吻合,相比之下分光光度法更为简单快捷。分光光度法是以香草醛-高氯酸作为显色剂,通过茶皂素甙元显色,于554 nm为检测波长。在样品待测液中,加入香草醛-高氯酸1.0 m L,在温度为60℃的条件下反应15 min,显色效果最佳。该方法精密度高,显色后在40 min内吸光度稳定,平均加标回收率为98.28%(RSD=3.86%)。本实验建立了分光光度法测定茶皂素含量的方法,具有良好的准确度、精密度和稳定性,可用于茶皂素含量的测定。     

味精中硫化钠含量测定的探讨

文章建立了分光光度法测定味精中硫化钠的含童.结果表明,加标回收率为96.9%-98.2%,RSD相对标准偏差为1.9%-2.6%(n=3),在0-16.0μg浓度范围线性关系良好,相关系数r=0.9994.用紫外分光光度法测定味精中硫化钠的含童,此方法快速、简便、结果准确.     

分光光度法测定葡萄酒中尿素含量

目的:建立了分光光度法定量检测葡萄酒中尿素含量的方法。方法:采用强阳性离子交换树脂柱对葡萄酒中尿素进行分离,依据费伦反应原理,采用分光光度法测定洗脱液中尿素含量。结果:建立方法的最佳参数为丁二酮单肟最佳添加量6.0g/L,氨基硫脲最佳添加量0.10g/L,反应中煮沸时间为5min,用分光光度计在530nm波长下测定吸光度。方法的最低检出限0.5mg/L,相对标准偏差为3.1%～4.4%,回收率为92.8%～103.1%。结论:此方法简便快速、准确可靠,适合用于葡萄酒样品中尿素含量的定量检测。     

分光光度法测定有机物中锰含量

采用分光光度法测定有机物中锰含量。用不同的消化及处理方法对样品进行处理。结果显示,用分光光度法测定有机物中锰含量,与原子吸收光谱法比较误差小于10%;回收率在90%以上。方法步骤简便、快捷、准确度高、重复性好。比较了不同消化方法消化样品对测定结果的影响,并总结出了适合分光光度法测定锰含量的样品消化方法。初步总结建立了一套用分光光度法测定锰含量的检测方法。     

分光光度法测定固体蛋白饮料中蛋白质含量

目的建立分光光度法测定固体蛋白饮料中蛋白质含量的分析方法。方法采用分光光度法测定固体蛋白饮料中蛋白质含量,考察了该方法的线性、精密度及回收率,并与凯氏定氮法测得的结果进行比较评价。结果在氮含量为0~100μg时,分光光度法的标准曲线方程为C=229.6A_(400nm)-1.418,r~2=0.998,精密度实验相对标准偏差(relative standard deviation,RSD)为1.51%~2.53%,重现性实验RSD为1.46%~2.80%,5种饮料回收率分别为98.6%、99.2%、99.2%、98.3%、99.1%,与凯氏定氮法测的结果进行比较,无显著性差异。结论该法具有简便快速、准确度高、精密度高、重现性好、检测效率高优势,适合于固体蛋白饮料中蛋白质含量的测定。     

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.