溪黄草中黄酮类物质的提取工艺优化

研究利用超声波辅助提取溪黄草中黄酮类化合物的工艺条件。以黄酮类物质提取率为指标,通过单因素试验、正交试验确定了溪黄草中黄酮类物质的最佳提取工艺条件。结果表明:溪黄草黄酮类物质的最佳提取工艺条件为:超声功率为225 W,乙醇浓度为65%,提取温度为50℃,料液比为1∶46(g/m L),超声提取时间25 min。在最优条件下,黄酮类化合物的提取得率可达6.84%,提取的效果最佳,且资源消耗低。     

超声波辅助提取枇杷花黄酮类化合物工艺的优化

研究超声波辅助乙醇浸提法从枇杷花中提取黄酮类化合物的工艺。通过单因素试验确定了影响黄酮类化合物的主要因素及较优水平,用正交试验优化提取工艺条件。结果表明,最佳工艺为:超声波功率为250 W,乙醇体积分数60%,提取温度60℃,提取时间40 min,料液比1︰20。最佳条件下枇杷花黄酮类化合物含量为83.7 mg/g。     

革命菜黄酮类化合物提取及其抗氧化性研究

目的：优化提取革命菜黄酮类化合物的最佳工艺条件并测定其体外抗氧化性。方法：采用L9(34)正交试验法研究从革命菜中提取黄酮类化合物的最佳提取工艺,考察乙醇体积分数、浸提温度、浸提时间及料液比四因素对提取效率的影响,并测定其体外抗氧化活性。结果：革命菜黄酮类化合物的最佳提取工艺条件为乙醇体积分数70%、浸提温度65℃、浸提时间3.5h、料液比1:30(g/mL)。在最佳工艺条件下,测得革命菜中黄酮类物质提取量为31.88mg/g;革命菜黄酮类化合物对羟自由基具有明显的清除作用,且随着黄酮质量浓度增加,清除能力增强;对超氧阴离子自由基具有一定的抑制作用。结论：革命菜黄酮类合物抗氧化活性明显,具有开发利用价值。     

桑葚叶黄酮类化合物提取工艺的优化

采用分光光度法,以芦丁为标准样品,测定桑葚叶黄酮类化合物的含量。在考察各影响因素的基础上设计正交试验,得出各因素对提取效果的影响主次顺序为料液比提取时间提取温度乙醇浓度,桑葚叶黄酮类化合物的最佳提取工艺为提取温度60℃,料液比1∶14(g/mL),乙醇浓度70%,提取时间90 min,提取2次。最佳条件下,黄酮类化合物的含量为50.2 mg/g。     

响应面法优化刺槐花黄酮类化合物的微波提取工艺

目的：利用响应面法对刺槐花黄酮类化合物的提取工艺进行优化。方法：在单因素试验的基础上,选择液料比、乙醇体积分数、微波时间为自变量,黄酮类化合物提取量为响应值,利用响应面分析法,研究各自变量交互作用及其对黄酮类化合物提取量的影响,模拟得到二次多项式回归方程的预测模型。结果：刺槐花黄酮类化合物的提取工艺为乙醇体积分数75%、液料比37:1(mL/g)、微波时间145s、提取两次。结论：在最佳工艺条件下黄酮类化合物提取量为8.63mg/g。     

白花蛇舌草和半枝莲总黄酮提取工艺优化及抗氧化性研究

探讨白花蛇舌草和半枝莲中黄酮类物质提取的优化工艺,以及最佳提取工艺条件下的黄酮类物质提取液的抗氧化性。在单因素试验基础上进行响应面试验,制定黄酮类物质提取工艺的三因素三水平响应面法试验设计方案。结果表明,获得较高总黄酮得率的最佳试验因素参数组合为:乙醇浓度74%、液固比70∶1(mL/g)、浸提时间5h。在此条件下,总黄酮得率为7.26%。该工艺所得黄酮类物质提取液对羟基自由基以及超氧离子自由基均具有较强的清除能力:当黄酮类物质提取液浓度为0.4 mg/mL时,黄酮类物质对羟基自由基的清除率达到最高,为57.16%;当黄酮类物质提取液浓度为0.3 mg/mL时,黄酮类物质对超氧阴离子自由基的清除率达到最高,为63.89%。     

超声波辅助水提紫苏活性成分工艺优化研究

研究超声波提取技术从紫苏梗中提取活性成分——黄酮类化合物和迷迭香酸的工艺条件。通过单因素实验法,考察了超声波功率、提取温度、提取时间及料液比四个主要因素对紫苏黄酮类化合物和迷迭香酸得率的影响,并用硝酸铝络合分光光度法,硫酸亚铁比色法来分别对黄酮类化合物和迷迭香酸进行了测定。在单因素实验基础上,采用正交试验优化其提取工艺。实验结果表明,影响紫苏梗中活性成分——黄酮类化合物和迷迭香酸的提取因素中温度是主要因素,因素主次为温度时间料液比功率,最佳提取工艺条件为:3%硼砂水溶液为提取剂,料液比为1:50(m/v),超声波输出功率为300W,提取时间为90min,提取温度为75℃。在此最佳工艺条件下,黄酮类化合物和迷迭香酸提取得率为34.6437mg/g。     

基于响应面分析法优化的黑三棱黄酮提取条件

在单因素试验的基础上,对乙醇浓度、提取时间、液固比和提取温度4因素进行Box-Behnken组合试验设计并通过响应面分析,优化黑三棱中黄酮类化合物的提取工艺。结果表明:提取黑三棱中黄酮类化合物的最佳工艺参数为乙醇体积分数66%、提取时间61min、液固比40∶1,提取温度81℃。在此条件下,黄酮类化合物的实际提取率为33.79mg/g,与预测值33.77mg/g基本一致。在4个因素中,乙醇体积分数对提取率影响最大,其次是提取温度,而提取时间、液料比对黄酮类化合物提取率影响较小,并且提取时间和提取温度的交互作用对黄酮提取率有较小影响,其他的因素间无交互作用。     

响应面法优化金丝小枣中黄酮类物质提取的最佳工艺

研究以乙醇为溶剂回流提取金丝小枣中黄酮类物质的工艺。在单因素试验的基础上,采用响应面法优化金丝小枣黄酮类物质的提取工艺,建立该工艺的二次多项数学模型,研究乙醇体积分数、回流温度、回流时间和料液比4个因素及其交互作用对提取工艺的影响。试验结果表明,回流加热提取金丝小枣黄酮类物质的最佳工艺条件为:乙醇体积分数为52.5%,回流温度为82.5℃,回流时间为90 min和料液比为1∶30,黄酮得率为6.097 8 mg/g。     

超声波辅助提取金线草黄酮工艺研究

以金线草为原料,黄酮类化合物提取率为指标,研究了超声波辅助法提取黄酮类化合物的最佳工艺条件。通过单因素试验研究了液料比、乙醇浓度、超声波处理时间3个因素对提取效果的影响,并利用响应面试验设计对提取工艺进行优化,得到最佳工艺条件为液料比23∶1(m L/g)、乙醇浓度75%、超声波处理时间11 min,在此条件下黄酮类化合物的实际提取率为2.576%。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.