挂糊油炸大球盖菇菌柄加工过程中挥发性风味物质变化研究

为明确挂糊油炸大球盖菇菌柄在加工过程中的挥发性物质风味变化规律,该文采用顶空固相微萃取结合气相色谱-质谱(headspace solid-phase microextraction gas chromatography-mass spectrometry, HS-SPME-GC-MS)以及电子鼻技术,定性定量分析其在鲜菌柄、挂糊、预炸和复炸4个加工过程共6组样品中挥发性风味物质的差异。结果表明,6组样品共鉴定出166种挥发性风味物质。通过计算相对百分含量和相对气味活度值,发现未油炸样品的挥发性风味物质以醇类和酯类为主,风味贡献最大的物质是1-辛烯-3-酮;油炸后的样品醛类含量占比最大,(E)-2-壬烯醛是风味贡献最大的化合物,并且油炸后风味物质的丰富度明显提高,增加了烤坚果香、巧克力香等香型。主成分分析(principal component analysis, PCA)发现不同加工过程的挥发性风味物质存在较大差异;电子鼻可有效区分油炸前和油炸后样品的挥发性风味物质。该研究从挥发性风味物质角度明确挂糊油炸大球盖菇菌柄加工过程中的风味特征,为大球盖菇的风味研究和拓宽其产品形式提供理论参考...     

栉孔扇贝柱和扇贝裙边中挥发性物质的比较分析

目的：探究栉孔扇贝柱和扇贝裙边在不同温度条件下的挥发性风味物质变化及两者的差异,为其加工提供参考。方法：运用电子鼻和顶空固相微萃取-气相色谱-质谱（headspace solid phase microextraction-gaschromatography-mass spectrometer,HS-SPME-GC-MS）联用仪对挥发性物质变化进行检测和分析。结果：电子鼻能够检测不同组织气味的变化,两者在新鲜与加热后的气味发生明显变化,最终利用HS-SPME-GC-MS分别从新鲜、90 ℃和120 ℃的扇贝柱和扇贝裙边中鉴定出16、20、7 种和18、18、20 种挥发性物质,主要有醇类、酮类、醛类、酯类、烃类等化合物。结论：新鲜、90 ℃和120 ℃的栉孔扇贝柱和扇贝裙边共有的挥发性物质分别为11、12、6种,存在差异的物质分别有13、14、15 种。丙酸戊酯、3-甲硫基丙醇和1-辛烯-3-醇在两者中的相对含量较高但是差距较明显,使得两者的风味有差异。电子鼻与HS-SPME-GC-MS结合使用后可以分析不同加热温度条件下扇贝柱和扇贝裙边挥发性物质的相对含量的变化及差异。     

兰州糟肉加工过程中挥发性风味物质的分析

以兰州糟肉为研究对象,分析其加工过程中挥发性风味物质的变化规律。采用固相微萃取-气相色谱-质谱(SPME-GC-MS)联用结合电子鼻技术,分别对原料期、炖煮期、腌制期、蒸煮期4个阶段的挥发性风味物质进行分离鉴定,并通过相对气味活度值(ROAV)法确定关键挥发性风味物质。结果表明:兰州糟肉加工过程中共鉴定出84种挥发性风味物质,4个阶段兰州糟肉挥发性风味物质的种类分别为37,23,23,40种,总相对含量呈现先增加后降低的趋势,在腌制期达到最大。4个阶段共有的风味化合物为5种,分别为四氯乙烯、甲苯、正己醛、2-正戊基呋喃和乙腈。相对气味活度值显示兰州糟肉加工过程中醛类、醇类物质的关键挥发性风味物质占主导地位,对兰州糟肉的风味贡献较大。电子鼻测定结果显示烷烃类、硫化合物风味活性较强。腌制期对兰州糟肉风味的影响较大。     

HS-SPME-GC-MS结合电子鼻分析烘烤对大球盖菇挥发性风味物质的影响

以大球盖菇为研究对象,利用顶空固相微萃取-气相色谱-质谱（head space-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）对挥发性风味物质进行定性定量分析,采用电子鼻区分不同烘烤温度（0、100、120、140、160、180 ℃）处理的大球盖菇挥发性风味物质,结合感官评定评价不同烘烤温度处理的大球盖菇香气特征。结果表明：HS-SPME-GC-MS共鉴定出挥发性风味物质87 种,其中醛类13 种、酯类17 种、醇类18 种、烷烃类4 种、酮类9 种、酸类8 种、吡嗪类4 种及其他类14 种,6 个不同处理的样品中均含有异戊醛、丙位戊内酯等25 种共有成分,烘烤过程中醛类物质、烷烃类物质和吡嗪类物质总含量有所提升,果香、玫瑰香和可可香气增加,醇类物质总含量减少;从整体气味感知来看,电子鼻可以快速有效区分不同烘烤温度处理的大球盖菇挥发性风味;根据相对气味活度值分析出34 种关键风味物质,其中异戊醛对风味贡献最大,具有麦芽香气和水果香气;140 ℃烘烤时生成风味物质种类最多,达到63 种,提高该样品风味的丰富度,增加果香、麦芽香、玫瑰香、坚果香和可可香,使该样品总体风味有所改善;通过感官评定表明烘烤使大球盖菇挥发性风味更为突出,并与上述检测结果一致。     

基于电子鼻和HS-SPME-GC-MS技术解析乌牛早茶的挥发性风味物质

为探究乌牛早的嫩叶和老叶在不同温度下挥发性物质成分,本文利用电子鼻测试不同温度下乌牛早茶叶的气味差异,并结合固相微萃取和气质联用(HS-SPME-GC-MS)技术对挥发性风味物质进行分析。结果表明:电子鼻能灵敏地检测到不同温度处理条件下嫩叶和老叶的气味变化,主成分分析(PCA)显示各个样品间差异明显。通过GC-MS分析在常温和处理温度40、60、80、100℃的乌牛早嫩叶中分别检测出15、20、14、17、17种挥发性物质,其主体风味成分主要有花果香味的芳樟醇、橙花醇等醇类物质。同时,在相同温度处理条件下的老叶中分别检测出21、21、19、18、27种挥发性物质,其主体风味成分主要有清新叶草香味的水杨酸甲酯等酯类物质。     

双斑东方鲀在冷藏保鲜过程中挥发性风味物质的变化

以双斑东方鲀鱼肉为研究对象,采用电子鼻及顶空固相微萃取-气相色谱-质谱（headspace solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）联用技术对冷藏（0 ℃和4 ℃）过程中双斑东方鲀鱼肉挥发性风味物质的种类和相对含量进行分析,探索鱼肉在冷藏过程中挥发性物质的变化规律。结果表明：双斑东方鲀在4 ℃和0 ℃条件冷藏1～3 d模糊数学感官评分较高,分别在7 d和9 d达到消费者可接受上限;电子鼻传感器响应值的主成分分析（principal component analysis,PCA）与线性判别分析能够对不同冷藏时期鱼肉中挥发性风味物质进行差异性分析,且分析结果与HS-SPME-GC-MS检测结果具有一致性。利用HS-SPME-GC-MS技术共检出48 种挥发性物质,包括烃类、醇类、醛类、酯类、芳香族化合物和含氮含硫杂环化合物,新鲜鱼肉具有鱼腥味、清新气味,冷藏11 d后,鱼肉的腥味增强,哈喇味、酸臭味加重,醛类和含氮含硫杂环化合物是导致其风味劣变的主要挥发性风味物质;结合气味活性值分析发现1-辛烯-3-醇、己醛、辛醛、壬醛和2,3-辛二酮是鱼肉在冷藏过程中的主要关键风味物质;使用PCA法构建挥发性风味物质综合评价模型为T=0.83T1＋0.15T2,评价结果与感官评价结果呈极显著负相关（P＜0.01）。由此可见电子鼻结合HS-SPME-GC-MS可用于双斑东方鲀在冷藏过程中的挥发性风味物质的区分与判别,可为研究不同冷藏时期的双斑东方鲀鱼肉风味变化提供理论参考。     

两种海洋甲壳动物挥发性物质的研究

目的:探明不同温度下两种海水甲壳动物(三疣梭子蟹和南美白对虾)的挥发性物质的变化情况。方法:用电子鼻(E-Nose)定性分析不同温度下三疣梭子蟹和南美白对虾的挥发性风味物质。采用顶空固相微萃取-气质联用仪(HS-SPME-GC-MS)定量分析其挥发性物质的变化。结果:电子鼻可检测到不同温度下气味的变化,经主成分分析(PCA)分析,三疣梭子蟹和南美白对虾的气味(挥发性物质)都在加热到100℃和150℃时发生较大变化。利用HS-SPME-GC-MS从新鲜、100℃及150℃的蟹和虾中分别鉴定出49,81和70种挥发性物质,主要有醇类、醛类、酮类、酚类、酯类、碳氢类等化合物。结论:加热前、后挥发性物质成分及含量的变化最终致使三疣梭子蟹和南美白对虾拥有各自独特的风味。两种肌肉在不同加热温度下所产生的主要挥发性物质有:正辛醛、2-戊基呋喃、2-甲基吡嗪和(Z)-4-庚烯醛等(三疣梭子蟹),二甲基三硫化物、4-乙基苯酚、2-乙酰基吡咯和三甲基吡嗪等(南美白对虾)。     

不同脱腥方法对鸡肝风味物质的影响

为研究不同脱腥方法鸡肝中风味物质的变化,采用感官评定、电子鼻与顶空固相微萃取-气质联用（headspace-solid phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS）技术,分析了不同脱腥方法的生熟鸡肝样品的挥发性风味物质。结果表明:姜酒浸泡、β-环状糊精包埋和酵母发酵均能显著降低生样品腥味值（P<0.05）;电子鼻响应值雷达图显示,组成鸡肝整体气味主要是硫化物、芳香成分和醇、醛酮类物质,姜酒浸泡能改变鸡肝原本的气味轮廓,且采用主成分分析（PCA）能较好区分各样品;HS-SPME-GC-MS共检出了124种挥发性风味物质,经姜酒浸泡和酵母发酵后,鸡肝中醛类物质含量均明显降低,多种致腥物质含量均明显下降。鸡肝熟化后,苯甲醛构成了鸡肝的主体风味,姜酒浸泡组中的乙醇含量明显高于对照组和酵母发酵组,是鸡肝熟化后保持较好风味的因素。研究表明,姜酒浸泡和酵母发酵能较好地改善鸡肝风味。     

三种香型食用牛油的挥发性风味物质分析及鉴定

为了探究3种不同香型(无香、淡香、浓香)食用牛油的挥发性风味物质的差异及其形成机制,利用电子鼻结合顶空固相微萃取-气质联用技术(headspace solid-phase microextraction-gas chromatography-mass spectrometry,HS-SPME-GC-MS)测定了3种牛油中的挥发性成分及其相对含量,并采用相对气味活度值法(relative odor activity value,ROAV)分析了牛油中的关键风味物质。结果发现,电子鼻能够灵敏地检测出不同香型牛油气味的差异性,而且线性判别方法效果优于主成分分析。HS-SPME-GC-MS检测出风味物质总共62种,其中醛类化合物贡献了绝大部分的香气,主要包括异戊醛、己醛、庚醛、辛醛和壬醛,而(E,E)-2,4-壬二烯醛、戊醛有不同程度増香的作用。除醛类物质外,右旋萜二烯和2-正戊基呋喃也对不同牛油的香气有相应的贡献,(-)-柠檬烯、2-甲基萘是浓香型牛油特征风味的重要来源,酯类化合物对增强牛油风味可能有其特殊作用。不同香型牛油的主要风味物质及相对含量有明显差异,初步推测其风味形成机制在于醛类化合物是造成不同香型牛油香气差异的关键风味物质成分。     

电子鼻结合顶空固相微萃取-气相色谱-质谱联用技术对干制乌贼挥发性成分分析

以乌贼为研究对象,采用电子鼻技术,结合顶空固相微萃取-气相色谱-质谱（headspace-solid phasemicroextraction-gas chromatography-mass,HS-SPME-GC-MS）联用技术,分析晾晒和热风烘干处理对乌贼挥发性风味物质的影响。结果表明,电子鼻分析结果能够很好地区分新鲜、晾晒和热风烘干3 种乌贼样品的风味。采用主成分分析、负荷加载分析以及线性判别分析可以量化主成分贡献率、传感器识别效应和样品间的风味区分度。HS-SPME-GC-MS分析结果表明,3 种样品共检出116 种不同的挥发性风味物质。其中新鲜乌贼为52 种,晾晒乌贼为64 种,热风烘干乌贼为71 种。新鲜乌贼经干制加工后,风味物质变化明显,产生新的醛类、烃类以及吡嗪类物质,而胺类物质的相对含量相对减少。吡嗪类物质在热风烘干乌贼中相对含量很高,是构成其特有的挥发性风味的主要贡献物质。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

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.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

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.