茶树花多酚提取工艺的研究

用常规水浴浸提法和超声波辅助浸提法来提取茶树花中的多酚，研究了浸提温度、时间、料液比等因素对多酚得率的影响，比较得出超声波辅助浸提用时短，温度低的优点；通过正交试验设计，研究了各因素对多酚浸提影响的主次顺序，确定了最佳提取参数。实验结果采用统计软件（SPSS）进行分析，影响超声波辅助浸提各因素的主次顺序为料液比、温度、浸提时间,超声波辅助浸提最佳工艺为：温度50℃、提取时间10min、料液比1：30，在此工艺条件下多酚浸提得率75．13ms／g干花。为茶树花资源深度研究开发提供依据。     

不同方法提取甜荞麦麸皮总黄酮研究

为提高荞麦麸皮利用率,采用乙醇浸提法、超声波辅助提取法和微波加热提取法对提取甜荞麦麸皮黄酮类化合物工艺进行研究。实验结果表明,乙醇浸提法最佳工艺条件为:用50倍50%乙醇在70℃水浴中浸提2.5 h,浸提三次,总黄酮得率为2.4195%;超声波辅助提取法最佳工艺条件为:用60倍70%乙醇在70℃下超声波30 min,超声波提取三次,总黄酮得率为2.8953%;微波加热提取法最佳工艺条件为:用40倍50%乙醇在360 W功率下加热90 s,提取两次,总黄酮得率为2.7963%。比较三种方法结果,以超声波辅助提取法较优,更适于工业化生产。     

超声波乙醇浸提法提取甘薯茎叶中总黄酮的工艺研究

以鄂薯4号甘薯茎叶为材料,通过单因素和正交试验对超声波乙醇浸提法提取甘薯茎叶总黄酮的工艺进行研究。结果表明,超声波乙醇浸提法提取甘薯茎叶总黄酮的最佳提取工艺为:超声温度40℃、乙醇浓度70%、料液比1∶40(g/m L)、超声时间30 min,在此工艺条件下甘薯茎叶总黄酮的得率可达2.65%。     

响应面法优化红巨苋多酚的提取工艺及抗氧化性

以红巨苋为材料,采用有机溶剂浸提法,在单因素试验的基础上,选取乙醇体积分数、料液比、浸提时间进行三因素三水平的Box-Benhnken中心组合试验,并通过响应面分析法对提取工艺参数进行优化;同时,对红巨苋叶片多酚物质的DPPH和OH自由基的清除能力进行分析。结果表明,红巨苋叶片多酚最佳提取工艺条件为:乙醇体积分数70%,料液比1∶51g/ml,浸提时间31min;三因素对提取率的影响大小依次为乙醇体积分数、料液比、浸提时间。在此条件下,红巨苋叶片多酚得率实际平均为13.92%,与理论预测值13.94%相近。红巨苋叶片多酚类物质对DPPH和OH自由基的清除率都在一个较高的水平,具有明显的抗氧化作用。     

苹果多酚的提取及其抗氧化陛的研究

苹果多酚是苹果中所含的多元酚类物质的通称。本试验研究了超声波辅助乙醇浸提法提取苹果多酚的最佳提取工艺。以陕西富士、甘肃静宁富士和蛇果为试验材料,测定了各种苹果果皮和果肉中总酚的含量,并比较了三种苹果多酚的抗氧化性能。结果表明,果皮的总酚含量显著高于果肉,且不论在果皮还是果肉,蛇果中提取的总酚含量显著高于其他两种苹果;试验确定的苹果多酚的最佳提取工艺为超声波处理20mim、料液比1：8、乙醇体积分数70％,且料液比为最主要的影响因素;总体而言,蛇果的抗氧化性能较好,且随着多酚浓度的增加,抗氧化性增强。总之,苹果多酚是一种天然的优质的抗氧化剂,应广泛应用于食品工业生产中。     

核桃雄花中总多酚提取工艺的研究

采用单因素和正交试验研究核桃雄花中多酚类物质的最佳提取工艺条件。通过对4种不同溶剂(无水乙醇、甲醇、丙酮和乙酸乙酯)在相同试验条件下的浸提效果比较发现,甲醇是核桃雄花中总酚类物质的最佳提取试剂。然后分别采用常规水浴浸提法和超声波辅助浸提法对甲醇体分数、浸提温度、浸提时间和料液比等因素进行研究,在确定最佳单因素水平的基础上,再利用正交试验优化以甲醇为浸提剂的提取工艺条件,试验得出超声波辅助浸提法具有用时短、总多酚提取量高的优点,其最佳工艺条件为:料液比1∶30(g/m L)、甲醇溶液体积分数30%、温度70℃、浸提时间10 min。在此条件下,核桃雄花中的总多酚含量可达6.56%,明显高于其他条件下的。     

川楝果实中川楝素不同提取方法的研究

为了获得川楝素最佳提取方法,以川楝果实为材料,采用高效液相色谱法检测,通过正交实验,分别研究溶剂浸提法、索氏提取法和超声波法提取川楝素的最佳提取条件。结果表明:溶剂浸提法的最佳提取工艺条件为:乙醇浓度70%,液料比8:1(mL/g),提取时间20min,提取次数3次,川楝素得率0.482%;索氏提取法提取川楝素的最佳工艺条件为:乙醇浓度70%,液料比15:1,提取时间4h,川楝素得率0.599%;超声波法提取川楝素的最佳工艺条件为:乙醇浓度80%,液料比12:1(mL/g),提取时间35min,超声功率450W,川楝素得率0.580%。三种提取方法进行比较,索氏提取法川楝素得率最高,为川楝素的最佳提取方法。     

玫瑰果多酚的提取

以玫瑰果实为原料,采用乙醇浸提法提取玫瑰果多酚类物质。通过单因素及正交试验研究了不同的乙醇体积分数、固液比、提取温度、提取时间和提取次数对多酚得率的影响。结果表明:各因素对玫瑰果多酚得率影响的主次顺序为乙醇体积分数>提取温度>料液比>提取时间;优化提取工艺条件为乙醇体积分数75%,固液比1∶20(g∶mL),浸提温度70℃,提取时间40 min,提取2次。在该优化条件下提取,玫瑰果多酚得率达到9.18%。     

苹果多酚的提取及其抗氧化性的研究

苹果多酚是苹果中所含的多元酚类物质的通称.本试验研究了超声波辅助乙醇浸提法提取苹果多酚的最佳提取工艺.以陕西富士、甘肃静宁富士和蛇果为试验材料,测定了各种苹果果皮和果肉中总酚的含量,并比较了三种苹果多酚的抗氧化性能.结果表明,果皮的总酚含量显著高于果肉,且不论在果皮还是果肉,蛇果中提取的总酚含量显著高于其他两种苹果;试验确定的苹果多酚的最佳提取工艺为超声波处理20mim、料液比1.8、乙醇体积分数70％,且料液比为最主要的影响因素;总体而言,蛇果的抗氧化性能较好,且随着多酚浓度的增加,抗氧化性增强.总之,苹果多酚是一种天然的优质的抗氧化剂,应广泛应用于食品工业生产中.     

‘赤霞珠’葡萄皮渣中原花青素的提取工艺研究

研究乙醇浸提法和微波辅助浸提法提取“赤霞珠”葡萄皮渣原花青素的工艺。乙醇浸提法研究提取时间、提取温度、料液比、乙醇浓度四个因素对原花青素提取率的影响;微波辅助浸提法研究微波时间、乙醇浓度、料液比三个因素对原花青素提取率的影响。乙醇浸提法的最佳提取工艺为：提取时间55min,提取温度50℃,料液比1:8.5(g/ml),乙醇浓度55%,提取率为2.61%;微波辅助浸提法的最佳提取工艺为：微波功率320W,微波时间30s,乙醇浓度50%,料液比1:13(g/ml),50℃恒温水浴中浸提30min,提取率为3.99%。在最佳提取工艺条件下研究pH 值对原花青素提取率的影响。乙醇浸提法和微波辅助浸提法分别在pH4.5 和pH5 时,原花青素提取率最大,提取率分别为2.67% 和4.11%,表明酸提高了原花青素的提取率。     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.