超临界CO_2流体提取苦参中总黄酮

目的研究超临界流体法提取苦参中黄酮类化合物的最佳工艺。方法采用单因子及正交试验,考察提取温度、压力、时间以及夹带剂流量对苦参黄酮类化合物提取量的影响。结果苦参黄酮类化合物提取工艺的最佳参数组合为：温度30℃,压力30MPa,乙醇流速0．4mL／min,时间60min。最佳条件下总黄酮提取率5．82％。结论超临界CO2提取苦参中总黄酮工艺简单、提取率高,可替代已有的方法。     

白簕根皮中提取黄酮工艺的研究

目的：确定白簕根皮中总黄酮最佳提取工艺。方法：采用微波辅助法提取白簕中的黄酮类化合物,通过单因素试验和正交试验,考察微波提取条件(溶剂、微波辐射时间、微波功率和固液比)对白簕中总黄酮提取率的影响。结果：白簕根皮总黄酮提取最佳工艺为：溶剂50% 乙醇、微波辐射时间30s、微波功率320W、固液比为1:20。结论：在此工艺条件下提取,总黄酮得率为30.04mg/g。     

穿心莲总黄酮微波辅助提取工艺的研究

通过单因素、正交实验及其方差分析探索微波辅助萃取法提取穿心莲黄酮类化合物的最佳工艺条件,采用紫外分光光度法测定总黄酮含量.结果表明影响实验因素的主次顺序是:乙醇浓度＞固液比＞微波作用功率＞微波作用时间,其中乙醇浓度、功率、固液比对总黄酮的提取都有显著影响.最佳提取工艺为微波功率处于高火、微波作用时间6min、固液比1:...     

微波辅助提取刺槐种子中黄酮类化合物的工艺参数优化

采用二次通用旋转组合设计研究了刺槐种子中黄酮类化合物的提取工艺。结果表明：四个因素对刺槐种子中黄酮类化合物提取率影响大小的顺序依次为：乙醇浓度〉功率〉时间〉料液比。其中乙醇浓度、微波功率及二者的交互项对刺槐种子中黄酮类化合物的提取率有极显著影响;微波时间有显著影响：料液比无显著影响。最佳工艺参数为：乙醇浓度60％、微波功率800W、萃取时间40s、料液比1：30。在此条件下,刺槐种子中黄酮类化合物的理论提取率为31．99mg／g,验证值31．47mg／g,二者基本一致。     

微波法提取党参黄酮的最佳提取工艺研究

本文采用微波提取法提取党参中的总黄酮;对其中是否含有黄酮类化合物进行了化学定性研究;对党参中总黄酮的微波提取工艺进行了优化。结果表明：山丹茎中含有黄酮类化合物：影响党参中总黄酮提取效率的四大因素的影响次序为提取浓度〉微波功率〉料液比〉微波提取时间：最后通过单因子试验确定了党参黄酮微波提取的最佳条件为微波功率600W,微波加热150s,乙醇浓度60%,料液比1：40,该工艺条件下总黄酮得率达2．5％。与传统提取方法相比。微渡提取法具有节省时间、节约能量、提取效率高、控制方便等优点。     

微波辅助提取洋葱黄酮类化合物的工艺研究

利用微波辅助提取洋葱中黄酮类化合物,采用正交试验优化工艺条件。结果表明：影响洋葱黄酮类化合物得率的主次因素顺序为微波萃取时间＞微波功率＞乙醇体积分数＞料液比。最佳的提取工艺参数为微波功率960W、萃取时间60s、乙醇体积分数70%、料液比1:60。在此条件下,黄酮类化合物的得率为1.81%。     

微波法提取川桂叶总黄酮工艺条件的研究

首次利用微波法提取川桂叶中的黄酮类化合物,探讨了乙醇浓度、固液比、提取温度、提取时间和提取次数等因素对总黄酮得率的影响,通过L（934）正交试验确定了提取的最佳工艺条件。结果表明：微波法提取川桂叶总黄酮的最佳工艺条件为：以65%乙醇按照固液比1∶20,在85℃条件下提取9min,连续提取2次,总黄酮得率为22.36mg/g。     

微波辅助提取山楂黄酮类化合物的工艺

利用微波辅助提取山楂中黄酮类化合物,采用正交试验优化了工艺条件,结果表明,影响山楂黄酮类化合物得率的主次因素顺序为微波萃取时间>微波功率>料液比>乙醇浓度。最佳的提取工艺参数为微波功率400 W,萃取时间120 s,乙醇浓度60%,料液比1∶40(g/mL)。在此条件下,黄酮类化合物的得率为3.19%。     

微波提取藏茵陈总黄酮的工艺

本文用微波提取法提取出了藏茵陈中总黄酮,通过化学方法对藏茵陈中总黄酮进行了定性鉴定,设计了正交试验考察影响总黄酮提取率的4个因素,设计单因子试验确定了这四大因素的最佳提取条件。结果表明：藏茵陈提取液中含有黄酮类化合物;微波提取藏茵陈中总黄酮的4个因素对提取效果影响的次序为乙醇浓度〉微波功率〉微波提取时间〉料液比,最佳的提取工艺为料液比1∶35,乙醇浓度70%,微波功率700W,微波提取时间8min,该工艺条件下总黄酮提取率达5.56%     

树莓叶黄酮类物质提取工艺条件优化

采用单因素实验和正交实验,研究微波提取法提取树莓叶中的黄酮类物质最佳提取工艺条件,结果表明：微波提取法提取树莓叶中总黄酮的最佳提取条件为：提取时间3min,料液比1g：40mL,乙醇体积浓度50％,功率250W,得率为5．81％。     

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.