阿魏菇多糖超声微波辅助提取及其抗氧化活性

以阿魏菇作为原料,水作为提取溶剂,通过响应面优化超声-微波协同辅助提取阿魏菇多糖工艺,并和传统水浴浸提法进行比较,采用清除DPPH·、·OH和O_2~-·模型对其体外抗氧化活性进行评价。结果表明:超声-微波辅助提取阿魏菇多糖的最佳的工艺条件为:料液比1∶50(g/m L),提取时间10 min,微波功率60 W。与传统水浴浸提法相比,超声-微波辅助提取缩短了提取时间,阿魏菇多糖的得率由2.23%增加到5.6%。超声-微波协同辅助提取对阿魏菇多糖的结构基本没有影响。阿魏菇多糖具有较强的清除DPPH·、·OH和O_2~-·的能力,并与质量浓度呈一定正相关关系,当阿魏菇多糖质量浓度达到5 mg/m L时,对DPPH·、·OH和O_2~-·的清除率分别达到67%、59%和63%,但弱于VC的抗氧化活性。     

樟头红青皮总酚超声波提取工艺及其抗氧化性分析

采用超声波辅助提取樟头红青皮总酚,通过单因素试验,结合响应面法,确定了樟头红青皮总酚的最适提取工艺,并通过4个抗氧化体系(DPPH,ABTS~+,·OH,还原能力)来评价其抗氧化活性。结果表明:樟头红青皮总酚的最适提取工艺条件为乙醇浓度56.2%、料液比1:52、超声时间22.5 min、超声功率108.3 W、提取2次,此条件下总酚得率为25.04 mg/g。樟头红青皮总酚对DPPH、ABTS~+、·OH自由基的清除能力和还原能力低于Vc,差异极显著(P0.01);樟头红青皮总酚对DPPH、ABTS~+自由基的清除能力很强,半抑制浓度分别为1.160 mg/mL和1.477 mg/mL;在一定浓度范围内,樟头红青皮总酚浓度越高,其对·OH自由基的清除能力和还原能力越强。     

全缘栝楼多糖及提取物不同极性部位抗氧化研究

研究全缘栝楼多糖和提取物不同极性部位体外抗氧化活性。采用清除羟自由基(OH·)、[2,2'-连氨-(3-乙基苯并噻唑林-6-磺酸)二氨盐]自由基(ABTS+·)、DPPH测定法以及Fe3+还原/抗氧化能力(FRAP)法,评价全缘栝楼多糖和提取物不同极性部位的抗氧化能力。全缘栝楼多糖和提取物不同极性部位清除DPPH·能力均强于抗坏血酸(IC50=1.22 mg/m L),且多糖(IC50=0.030 mg/m L)和乙酸乙酯层(IC50=0.082 mg/m L)比茶多酚强(IC50=0.118 mg/m L);多糖(IC50=0.031 mg/m L)清除OH·能力比茶多酚(IC50=0.032 mg/m L)和抗坏血酸(IC50=0.044 mg/m L)强,而石油醚层(IC50=0.033 mg/m L)和乙酸乙酯层(IC50=0.038 mg/m L)强于抗坏血酸;清除ABTS+·能力均强于茶多酚(IC50=0.416 mg/m L),且多糖(IC50=0.008 mg/m L)强于抗坏血酸(IC50=0.011 mg/m L);Fe3+还原/抗氧化能力均强于茶多酚(FRA P=1 310.8μmol/g),但比抗坏血酸弱(FRAP=31 469μmol/g)。全缘栝楼多糖和提取物不同极性部位有较强的抗氧化能力,为其生物活性的深入研究提供了参考依据。     

微波提取白鹃梅黄酮类物质及其抗氧化活性研究

本文以白鹃梅为原料,采用微波辅助提取白鹃梅中黄酮类化合物。在单因素实验的基础上,利用响应面法对微波功率、时间、料液比、温度进行优化;并对其体外抗氧化活性进行测定。结果表明,微波功率、时间、温度对总黄酮提取量影响比较显著;最佳工艺条件为:微波功率357 W,时间63 min,料液比1∶26 g/m L,微波温度47℃,由此得到白鹃梅总黄酮提取量为14.59 mg/g,与预测值14.67 mg/g的相对误差为0.5%。总黄酮清除DPPH·、·OH、O-2·以及的IC50值分别为0.52、0.55、1.18 mg/m L。其清除DPPH·、·OH的能力高于BHT,而低于VC;清除O-2·的能力均低于VC、BHT。结论:微波辅助提取法能够提高白鹃梅中总黄酮提取量,且白鹃梅中黄酮类物质具有一定能力的抗氧化活性。     

白及多糖的超声-微波协同提取工艺及其抗氧化活性研究

目的:研究白及多糖的超声-微波协同提取工艺优化及其抗氧化活性。方法:以多糖得率为考察指标,通过单因素实验对料液比、浸泡时间、微波功率和协同提取时间4个影响因素进行考察,采用正交实验设计对超声波-微波协同提取白及多糖的工艺条件进行优化,并研究白及多糖对羟基自由基(·OH)、超氧阴离子(O_2~-·)和1,1-二苯基-2-苦肼基自由基(DPPH·)的清除率以评价其体外抗氧化活性。结果:最佳提取工艺条件为:液料比20∶1 m L/g,浸泡时间6 min,微波功率200 W,协同提取时间5 min,该工艺条件下多糖得率达6.98%±0.19%。单独超声波提取法和单独微波提取法的多糖得率仅为超声-微波协同提取法的46.28%和87.96%,表明超声-微波协同提取优于单独超声波提取和单独微波提取。抗氧化活性研究表明在实验范围内,白及多糖对O-2·无明显清除作用,但对·OH和DPPH·具有明显的清除作用,采用超声-微波协同提取法提取的白及多糖较微波提取法具有更高的·OH和DPPH·清除活性,当多糖浓度为0.5 mg/m L时,对·OH和DPPH·清除率分别为92.82%和74.21%。结论:超声-微波协同提取具有省时高效的特点,特别适用于多糖类物质的提取。     

核桃青皮果蔬酵素的成分组成及体外抗氧化活性研究

以核桃青皮和果蔬为原料,经过发酵、纯化制得核桃青皮果蔬酵素,对酵素的化学成分、功效酶和主要抗氧化成分含量进行测定,并对其抗氧化功效进行评估。结果表明:核桃青皮果蔬酵素的可溶性固形物、酸度、总糖和总蛋白含量分别为29.300%、1.959%、11.802 mg/m L和39.000 mg/m L,经感官品尝,酵素液酸甜适口、果醋香浓郁;其矿物质元素也较丰富,含量呈现KClMgNaCaPFeZn的趋势;酵素内功效酶测定结果显示,超氧化物歧化酶活性很高,可达1980.250 U/m L,而淀粉酶活较低;酵素内4个主要抗氧化成分含量高低顺序为:抗坏血酸总花青素总黄酮总多酚,其黄酮含量与冬枣酵素相当,而多酚含量远小于葡萄酵素;与火龙果酵素相比,核桃青皮果蔬酵素显示出更强的清除DPPH·、O_2~-·、·OH能力,同时核桃青皮果蔬酵素呈现出良好的还原力和总抗氧化能力,而对金属离子的螯合能力则较差。     

微波辅助提取垂丝海棠花中多糖及其抗氧化研究

目的:优化垂丝海棠花中多糖的微波提取工艺。方法:在单因素实验的基础上,采用Box-Behnken中心组合实验和响应面分析法,研究提取时间、微波功率、料液比对垂丝海棠花中多糖含量的影响,确立最佳提取工艺。同时,以DPPH自由基清除能力、还原Fe3+能力、清除·OH能力为指标研究垂丝海棠花多糖的抗氧化活性。结果:垂丝海棠花中多糖的最佳提取工艺为:微波提取时间15min,液料比30∶1(g/g),微波功率3k W。抗氧化实验结果表明,在达到最大浓度0.96mg/m L时,垂丝海棠花多糖(微波)、垂丝海棠花多糖(煮沸)对DPPH自由基的清除率依次为69.8%、59.5%,垂丝海棠花多糖(微波)、垂丝海棠花多糖(煮沸)对·OH自由基的清除率依次为80.1%、58.2%,对还原Fe3+能力较强。显示垂丝海棠花多糖有一定抗氧化活性,且垂丝海棠花多糖(微波)较垂丝海棠花多糖(煮沸)活性强。结论:微波提取垂丝海棠花中多糖较常规提取效率高,时间短,且抗氧化活性强。     

杜仲叶茯砖茶多糖提取工艺优化及抗氧化降血脂活性

目的:采用响应面法优化杜仲叶茯砖茶多糖提取工艺,并研究杜仲叶茯砖茶多糖的体外抗氧化降血脂活性。方法:通过单因素实验考察了提取时间、液料比、提取温度等对杜仲叶茯砖茶多糖得率的影响,在此基础上,采用响应面分析法优化提取工艺。考察了杜仲叶多糖对DPPH·,·OH,ABTS+的清除能力以及铁还原能力,并进行胆酸盐结合试验评价降血脂作用。结果:杜仲叶茯砖茶多糖最佳提取工艺如下:提取时间为1.5 h、液料比为25 m L/g、提取温度为51℃,在该最佳条件下,杜仲叶茯砖茶多糖得率为8.4769%。体外抗氧化实验结果表明,当多糖浓度为100μg/m L时,对ABTS+的清除率达98.74%;当多糖浓度为60μg/m L时,对DPPH自由基的清除率为69.28%;当多糖浓度为0.875 mg/m L时,对·OH的清除率为43.97%;当多糖浓度为0.28 mg/m L,杜仲叶茯砖茶多糖的铁还原力可达Vc的53.08%。体外降血脂实验结果表明,当多糖浓度为4.8 mg/m L时,其对牛磺胆酸盐和甘氨胆酸盐的结合率分别达到35.74%和63.77%。结论:该杜仲叶茯砖茶多糖优选提取工艺稳定可行,杜仲叶茯砖茶多糖具有较好的体外抗氧化降血脂活性。     

松针多糖微波提取工艺及抗氧化性研究

采用微波辅助法对松针多糖提取工艺进行了研究,通过考察提取温度、提取时间、提取功率和料液比对松针多糖得率的影响,在单因素实验基础上进行正交优化,确定了提取的最佳工艺参数为:提取温度90℃、提取时间10 min、提取功率800 W、料液比1∶14(g·m L~(-1)),提取两次,在优化条件下松针多糖的提取得率最高达2.1698%;此外,通过测定松针多糖还原能力、清除自由基的能力评价了其抗氧化活性,结果表明,松针多糖具有一定的抗氧化能力,对DPPH、·OH、ABTS~+·的半抑制浓度(IC_(50))分别为0.291、1.793、0.617 mg/m L。     

红松壳多酚、黄酮和多糖含量及抗氧化活性相关性的研究

为了探究红松壳中主要活性成分的含量及其与抗氧化活性之间的相关性,试验以伊春红松壳为原料,使用不同浓度乙醇溶剂提取红松壳多酚、黄酮和多糖并分析其含量,采用SPSS软件分析松壳中活性物质与抗氧化活性之间的相关性。试验结果表明,当乙醇的浓度为40%时,红松壳多酚、黄酮和多糖得率均最高,分别为4.05 mg/g、1.7 mg/g和7.05 mg/g。抗氧化活性试验表明,红松壳多酚抗氧化活性显著高于黄酮和多糖,与Vc抗氧化活性相当。其中松壳多酚对DPPH·的IC50(半数清除率浓度)值是0.20±0.05μg/m L,对·OH的IC50值是13.04±0.04μg/m L,对总还原力的IC50值是40.15±0.06μg/m L。相关性分析结果也表明松壳多酚与抗氧化活性相关性最高,其中松壳多酚与DPPH·相关性是0.908,与·OH相关性是0.989,与总还原力相关性是0.989(p0.01),可以看出松壳多酚是主要的抗氧化成分。本实验研究的结果为伊春红松壳副产物的综合利用以及开发天然抗氧化剂提供了科学依据。     

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.