苹果渣多酚大孔树脂分离及抗氧化性研究

以新鲜苹果渣为原料,乙醇为提取溶剂,超声波辅助提取多酚。考查了12种大孔树脂对没食子酸的吸附、解吸能力吸附量,选用XDA-8大孔树脂对苹果渣多酚进行吸附,60%乙醇溶液解吸。经浓缩、冷冻干燥制得苹果渣多酚粉末,并考查苹果多酚1,1-二苯基-2-苦苯肼自由基(DPPH·)、超氧阴离子(O2-·)和羟基自由基(维生素C)的清除效果。结果表明:XDA-8大孔树脂对没食子酸的吸附和解吸能力较强,吸附量达84.32%。苹果多酚对超氧阴离子(O2-·)和羟基自由基(·OH)的清除率高于BHT、PG和维生素C,它对1,1-二苯基-2-苦苯肼自由基(DPPH·)清除率高于BHT和PG,略低于维生素C。     

苹果渣多酚微波辅助提取工艺研究

以苹果渣为原料,采用乙醇作为提取溶剂,研究了在微波辐射下提取苹果渣多酚的工艺条件.探讨了苹果渣多酚的提取方法及相应的提取条件;对微波功率、溶剂浓度、料液比、提取时间等影响因素进行了研究,结果表明,微波辅助法从苹果渣中提取苹果渣多酚的适宜工艺条件为：苹果渣在70%乙醇溶液中,采用功率350W,提取时间240s.此条件下苹果渣多酚提取得率为2.42%.     

苹果渣多酚抗氧化性质的研究

为研究苹果渣多酚的抗氧化性质,分别测定了苹果渣多酚对.OH的清除作用、对.O2-的清除作用和对脂质过氧化的抑制作用。结果表明:苹果渣多酚提取物对.OH的清除能力、对.O2-的清除能力和脂质过氧化的抑制能力EC50分别为5.7mg/mL、6.7mg/mL和0.27mg/mL。苹果渣多酚提取物具有较强的抗氧化的作用。     

寒富苹果渣中多酚类物质超声波辅助提取工艺

以寒富苹果果渣为原料,以一定浓度乙醇溶液为提取剂,利用超声波辅助法提取苹果渣中的多酚。通过对乙醇浓度、超声波功率、超声波时间、料液比等条件进行单因素试验分析,并通过响应面法得出苹果渣中多酚的回归方程。确定多酚类物质的最佳提取工艺条件为乙醇浓度49%,超声波功率为370 W,作用时间为136 s,料液比为1∶30(g∶mL)。实际平均提取率1.71 mg/g。     

响应曲面法优化微波辅助提取苹果渣多酚工艺研究

为从苹果渣中提取具有生理活性的多酚物质,在单因素试验的基础上,采用响应曲面法优化微波辅助提取苹果多酚的工艺,建立该工艺的二次多项数学模型,研究微波功率、提取时间、乙醇体积分数和料液比4个因素及其交互作用对提取工艺的影响.试验结果表明,对苹果多酚得率的影响次序是:微波功率>料液比>提取时间>乙醇体积分数;微波辅助提取苹果渣多酚的最佳工艺条件是:微波功率650W、提取时间53 s、乙醇体积分数60%、料液比1:20(g/mL),多酚得率迭61.8286 mg/100 g干果渣.     

微波法提取苹果渣中多酚的工艺研究

以乙醇作为提取溶剂,研究了微波法提取苹果渣中多酚的工艺条件。主要探讨了溶剂浓度、微波功率、提取时间、料液比、物料颗粒等因素对多酚提取的影响,结果表明,微波法从苹果渣中提取多酚的最佳工艺条件为乙醇浓度60%、物料颗粒40目、液料比1∶10、微波功率350W、提取时间90s,此条件下从苹果渣中提取的多酚浓度可达245.31mg/100g,明显优于回流提取法和超声波提取法。     

苹果渣中多酚类物质的提取和应用研究进展

苹果多酚是苹果中多元酚类物质的总称,具有良好的保健和药理功能。本文主要论述了苹果渣中多酚类物质的组分、性质、生物活性以及干苹果渣中提取、纯化多酚类物质的研究及应用现状。     

甘薯渣多酚粗提液的抗氧化活性研究

多酚具有抗氧化特性。以从甘薯渣中提取的多酚类物质为材料,对其抗氧化性能进行了体外实验,分别测定了甘薯渣多酚粗提液对超氧阴离子自由基(O2-·)、H2O2、羟自由基(·OH)的清除能力及还原能力。结果表明,甘薯渣多酚提取物粗提液具有较强的综合抗氧化能力,是一种有开发价值的天然抗氧化剂。     

白地霉发酵苹果渣的产香特点研究

[目的]研究了白地霉TF发酵新鲜苹果渣和干苹果渣的产香特点.[方法]以苹果浓缩汁生产厂的新鲜苹果渣和干燥苹果渣为原料,接种白地霉TF,静置固态培养7d后,用固相微萃取法气相检测发酵体系中的挥发性成分;对照为未接种但经灭菌和相同条件培养后的苹果渣.[结果]共检出化合物86种,鉴定出化合物80种,其中,发酵前后新鲜果渣分别为31种和35种,发酵前后干果渣分别为32种和34种.未发酵苹果渣中的挥发性物质主要是酚、烷类及其它物质和醛、酮、酸类,酯类含量不到总挥发性物质的25%;发酵后苹果渣中挥发性物质中50%以上为酯类物质,醛、酮、酸类相对含量不到15%.发酵后新鲜果渣的主体酯类为2-甲基丁酸丁酯、2-甲基丁酸甲酯、异丁酸甲酯和己酸甲酯,相对含量分别为12.00%、8.50%、6.68%和6.13%;主体醇类为苯乙醇,相对含量为2.28%;发酵后干苹果渣中的主体酯类为4-癸烯酸甲酯、2-甲基丁酸甲酯、3-甲基丁酸甲酯和异丁酸甲酯,相对含量分别为10.40%、9.49%、6.16%和6.09%;主体醇类为苯乙醇,相对舍量为4.19%.[结论]白地霉TF发酵能够有效提高苹果渣中呈香性酯类的种类和含量,以及苯乙醇的含量,减少醛、酮、酸、酚、烷类及其它物质的种类和含量,改善苹果渣的风味.     

流动注射化学发光测定苹果多酚抗氧化活性

用流动注射化学发光法测定苹果多酚的体外抗氧化作用。将苹果多酚提取液加入3种化学发光体系,测量其发光强度,根据系统化学发光被抑制的程度评价苹果多酚对活性氧自由基的清除能力,并以抗坏血酸(VC)为阳性对照。结果表明,苹果多酚对三种活性氧自由基(O2-·、·OH、H2O2)的清除能力远强于VC;对H2O2和·OH的清除能力相当,强于对O2-·的清除能力。结果显示苹果多酚具有很好的抗氧化能力。     

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.