醪糟挥发性成分的顶空固相微萃取条件优化

采用响应面法对醪糟挥发性成分顶空固相微萃取（Headspace Solid Phase Microextraction,HS-SPME）条件进行优化,以总峰面积为指标,分析萃取时间、萃取温度和样品质量对醪糟挥发性成分的影响,确定了最佳萃取条件为时间52 min、萃取温度73℃、样品质量4.7 g,可为有效、快速优化醪糟的风味提供参考。     

响应面法优化顶空固相微萃取分析茉莉加香颗粒挥发性成分

目的 建立顶空固相微萃取(headspace-solidphasemicroextraction,HS-SPME)分析茉莉加香颗粒挥发性成分的检测方法。方法 采用HS-SPME和气相色谱-质谱法(gaschromatography-massspectrometry,GC-MS),以总峰个数为指标,在选定萃取头的基础上,采用单因素实验法分析萃取温度、萃取时间、解吸时间对萃取效果的影响,根据单因素实验结果运用Box-Benhnken中心组合实验设计响应面优化萃取条件,并在最优萃取条件下对茉莉加香颗粒挥发性成分进行分析鉴定。结果 50/30μmDVB/CAR/PDMS萃取头对茉莉加香颗粒挥发性成分萃取效果较好;响应面法得到最佳萃取条件为萃取温度62℃,萃取时间26.5min,解吸时间2.6min。在最佳条件下茉莉加香颗粒共检测出61种挥发性成分,占流出组分总量的87.97%,其中酯类16种、烯烃类21种、烷烃类7种、醛酮类3种、酚类1种、醇类2种、杂环类1种、其他类10种。结论 本研究建立了茉莉加香颗粒挥发性成分的检测方法,此方法快速准确,为加香颗粒挥发性成分的检测研究提供技术支撑。     

响应面分析法优化鱼露挥发性风味物质萃取工艺

采用HS-SPME-GC-GC-MS技术对鱼露的挥发性风味物质进行研究。为了优化鱼露风味检测的HS-SPME萃取效率,以出峰个数和峰体积为指标,在单因素实验的基础上,采用响应面优化试验确定鱼露中挥发性风味物质萃取的最佳条件。结果表明,萃取温度58 ℃,萃取时间70 min,振荡频率510 r/min,在此条件下模型预测得到的出峰个数最多为1558.55个,峰体积为7.56×1010。在最佳萃取条件下对银鱼鱼露样品进行挥发性风味物质检测,共检测到化合物152种,对其进行分类,其中化合物含量最多的是醇类和酯类,分别为26.02%和25.91%。建立的HS-SPME-GC×GC-MS分析鱼露挥发性风味物质的方法,可以更好地对样品中的成分进行分离,分辨率高。     

响应面法优化籼稻挥发性成分SPME萃取条件的研究

应用顶空固相微萃取(SPME)技术结合气相-质谱法(GC-MS)对籼稻挥发性成分进行分析,并优化SPME的萃取条件。首先考察萃取量、萃取温度、平衡时间、萃取时间、解析时间对籼稻挥发性成分萃取的影响,在单因素试验的基础上进行响应面分析优化SPME萃取条件,以优化的最佳条件结合GC-MS对籼稻挥发性成分进行分析。结果表明:籼稻挥发性成分的最佳SPME萃取条件为萃取温度75℃、平衡时间59min、萃取时间60 min、解析时间5 min。籼稻含有烃类、醛类、含氮含氯含氧及杂环类、酸酯类、酮类、醇类等84种挥发性成分。     

顶空固相微萃取茶油挥发性成分的响应面优化

挥发性成分组成及含量是油茶籽油特色风味形成的重要影响因素,结合顶空固相微萃取技术(headspace solid phase micro-extraction,HS-SPME)和气相色谱-质谱法(gas chromatography-mass spectrometry,GC/MS),探讨茶油挥发性成分的最佳萃取条件。在单因素试验基础上,选用50/30μm DVB/CAR/PDMS萃取头,进行响应面优化分析HS-SPME萃取条件。结果表明,HS-SPME-GC/MS法分析茶油挥发性成分的最佳条件为萃取温度70℃、萃取时间31 min,解析时间3 min。此条件下检测出70种茶油挥发性物质,与预测值偏差2.66%,总峰面积2.16×10~7,其中醛类、酮类、酯类、烷烃类、醇类、酸类和萜烯类分别含有16、12、12、12、7、6和5种挥发性化合物,其相对含量分别为39.95%、7.42%、3.07%、6.87%、6.50%、33.70%和2.47%。     

基于响应面分析法优化顶空-固相微萃取与气相色谱-质谱法检测黑龙江野生鳜挥发性风味物质

目的 使用响应面分析法优化顶空-固相微萃取(headspace-solid phase microextraction,HS-SPME)与气相色谱-质谱法(gas chromatography-mass spectrometry,GC-MS)联合检测黑龙江鳜肌肉风味的萃取方法,并检测分析鳜肌肉中挥发性风味物质。方法 使用HS-SPME-GC-MS技术,以峰面积和峰个数为指标进行单因素实验,探究盐度、萃取温度、萃取时间和解吸时间对鳜肌肉风味检测的萃取效率的影响,根据单因素实验结果采用响应面方法优化萃取条件,分析鳜肌肉中挥发性风味物质的最佳萃取条件,并用优化后的萃取条件检测鳜的挥发性风味物质。结果 优化后的最佳萃取条件为盐度7.7%,萃取温度82.4℃、萃取时间46.5 min、解吸时间5.4 min。此条件下,综合评分为101.4173,共检测出33种挥发性风味物质,其中化合物含量最多的是烃类和醇类。结论 优化后的HS-SPME-GC-MS分析鳜肌肉挥发性风味物质的方法可以高效萃取鳜肌肉中的风味物质。     

顶空-固相微萃取和同时蒸馏萃取法提取肉桂的挥发性成分

挥发性成分的提取方法对分析武夷肉桂香气成分具有重要影响。本文比较顶空固相微萃取法(HS-SPME)和同时蒸馏萃取法(SDE)提取武夷肉桂的挥发性成分的的差异,采用气相色谱-质谱联用技术(GC-MS)表征其挥发性成分。首先优化HS-SPME的萃取条件,其最优萃取条件为:50/30 μm DVB/CAR/PDMS萃取纤维,萃取温度50 ℃,萃取时间50 min,NaCl添加量30%。在此条件下共检出84种挥发性成分;再通过SDE法提取到40种挥发性成分,两种方法共同检出的成分有26种,对酯类的萃取效率相当。HS-SPME在提取杂环类化合物、中、低沸点脂肪族醇类、烯烃类、酮类的效率高于SDE;而SDE更有利于萃取沸点较高的醇类、酸类和酚类等成分。结论:分析武夷肉桂的香气成分应结合HS-SPME和SDE两种方法。     

顶空固相微萃取结合GC/MS分析玫瑰香型滇红茶香气成分

采用顶空固相微萃取(HS-SPME)结合气相色谱-质谱联用技术(GC-MS)对玫瑰香型滇红茶样品中的挥发性香气成分进行分析,同时与普通滇红茶的挥发性成分进行比较。实验首先对HSSPME参数进行优化,确定了HS-SPME最优参数为:65μm PDMS/DVB萃取头,萃取温度60℃,萃取时间60 min。从玫瑰香型滇红茶和普通滇红茶中分别检测出62种和58种香气成分,各占其总香气成分的93.23%和93.85%,主要为醇类、碳氢类、酯类、酮类、醛类、酸类和含氮类化合物。2种茶叶中具有玫瑰香或类似玫瑰香的化合物共6种,分别为芳樟醇、苯乙醇、香叶醇、β-大马烯酮、香叶基丙酮、(E)-橙花叔醇,在玫瑰香型滇红茶和普通滇红茶中的总相对含量分别为36.29%和15.51%,玫瑰香型滇红茶6种化合物的总相对含量约为普通滇红茶的2.2倍。该研究结果为玫瑰香型滇红茶香气的进一步研究提供了一定的理论依据。     

酱牛肉加工过程中挥发性成分的含量变化分析

为探讨酱牛肉加工过程中挥发性成分组成及变化规律,设计正交试验对顶空固相微萃取(HS-SPME)条件及解吸时间进行优化,并结合气相色谱质谱联用(GC-MS)对酱牛肉加工过程各阶段样品中的挥发性成分进行检测分析。结果表明,在萃取温度60℃,萃取时间60 min,解吸时间5 min的条件下效果最优。鉴别出酱牛肉加工过程中挥发性成分的总数是90种,其中包括醇类22种、醛类11种、酯类16种、烃类14种、酮类8种、含硫含氮及杂环类13种和其它化合物6种。六个加工阶段样品的挥发性成分的种类数量分别为45种、48种、53种、52种、61种和58种。加工过程中各类挥发性成分的相对含量不断发生变化,同类挥发性成分在六个加工阶段的组成也不一致。本研究结果为改进酱牛肉的生产工艺、提高产品品质提供了理论参考。     

优化GC检测欧李酒香气成分的萃取条件

香气物质的组成表征果酒的特色,利用响应面法优化顶空固相微萃取(HS-SPME)欧李果酒中香气物质的条件,使气相色谱法检测香气物质的结果更精确。本文采用HS-SPME结合GC-FID检测欧李发酵酒中的香气物质,在单因素实验的基础上,以加盐量、萃取温度、萃取时间为影响因素,出峰面积为响应值,运用Box-Benhnken中心组合实验设计原理进行响应面分析,优化了HS-SPME的萃取条件。结果表明,HS-SPME萃取欧李发酵酒中香气成分的适宜条件为:加盐量0.226g/mL、萃取温度29℃、萃取时间36min。该条件下萃取,结合GC-FID测得欧李发酵酒中32种香气成分,对其中10种进行了定性和定量分析,含量较高的有:异戊醇110.734mg/L、己酸乙酯11.568mg/L、异丁醇8.7725mg/L、苯乙醇47.178mg/L、乙酸异戊酯15.655mg/L、丙醇1.7032mg/L。     

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.     

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.     

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.     

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.