酶法水解芝麻粕制备芝麻多肽

以芝麻制油后副产物芝麻粕为原料,采用蛋白酶水解法制取芝麻多肽。在水解酶筛选、单因素试验基础上,以多肽产率为指标,设计正交试验对碱性蛋白酶酶解芝麻粕制取芝麻多肽工艺进行了优化。结果表明,最佳工艺参数为:pH 9.0,料液比1∶20,加酶量11 000 U/g,酶解时间2.5 h,酶解温度65℃。在此条件下,多肽产率达到3.51%。     

酶法制备碎米抗氧化肽的研究

以碎米为原料,采用酶法制备抗氧化肽。以水解物的还原力为评价指标,利用不同蛋白酶水解碎米蛋白,结果得出风味蛋白酶为最佳水解酶;通过单因素和正交实验,得到最佳酶解工艺条件：液料比6∶1（mL/g）、pH6.5、加酶量4000U/g、酶解温度53℃、酶解时间3h,在此条件下水解液还原力最大。     

响应面优化碎米蛋白水解及多肽抗氧化研究

为研究碎米蛋白水解工艺条件及其水解产物的抗氧化特性,实验以碎米为原料,以水解度为指标,筛选最适酶解大米蛋白的酶,在单因素的基础上以温度、底物质量分数、酶添加量、pH为响应因子,以碎米蛋白的水解度为响应值,采用Design-Expert 8.0.6.1软件对水解工艺进行优化,并对米蛋白肽的抗氧化活性进行研究。结果表明:碱性蛋白酶是生产米蛋白肽的最适合酶类;碎米蛋白最佳水解工艺为:温度63.7℃、底物质量分数4.4%、酶添加量6.8%、pH为8.5,水解度预测值为24.56%,得到水解度的实际值为25.2%。此条件下得到的碎米蛋白肽具有显著的羟自由基和超氧自由基清除能力,在水解180min、210min时羟自由基和超氧自由基清除率出现最高值为28%、33%,因此,水解180min为制备抗氧化肽的最佳时间。     

碎米蛋白ACE抑制肽制备工艺的研究

研究了以碎米为原料,酶法制备血管紧张素转换酶(ACE)抑制肽的工艺。采用不同的蛋白酶对碎米蛋白进行水解,以水解液对ACE抑制率为评价指标,结果得出风味蛋白酶为最佳水解酶;通过单因素和正交试验,确定最佳的酶解工艺条件:pH为7.0,酶解温度为55℃,料液比为3%,酶解时间3h,风味蛋白酶酶添加量4000U/g。在此条件下ACE抑制肽的抑制率为85.4%。     

碎米制备高果糖浆的工艺研究

研究碎米制备高果糖浆的工艺,主要对碎米葡萄糖异构化制取果葡糖液、钙型树脂分离果糖和葡萄糖获得高果糖浆的工艺进行优化。通过单因素和正交试验,得到制取果葡糖液的最优条件：异构酶加酶量9mg/g 碎米葡萄糖、pH7.5、反应温度70℃、反应时间35h;通过正交试验,得到树脂分离制取高果糖浆的最优条件：分离温度70℃、糖液体积分数20%、洗脱液流速4mL/min、进料量40mL。在优化条件下获取的高果糖浆果糖含量为89.64%。     

响应面法优化油茶籽多肽制备的工艺研究

针对油茶籽加工副产物利用率低,油茶籽多肽制备得率和纯度不高等问题,本研究利用中性蛋白酶对油茶籽蛋白进行水解,研究了酶解pH、酶解温度、底物浓度、加酶量和酶解时间5个单因素对油茶籽多肽制备的影响,在单因素试验的基础上,选取了底物浓度、酶解温度和加酶量3个因素,采用综合平衡法,以酶解后油茶籽蛋白的水解度、游离氨基酸浓度和多肽浓度隶属度的综合分为指标,进行三因素二次旋转试验设计,并进行响应面分析,以优化油茶籽多肽的制备条件,优化结果底物浓度3.00%、酶解温度47.0℃、加酶量6 440 u/g底物,在该优化条件下的试验显示,油茶籽蛋白水解度19.25%、游离氨基酸浓度76.60μmol/mL、油茶籽多肽浓度61.35 mg/mL,综合分0.985,优化结果理想,说明该工艺可生产质量较好的小分子多肽,为油茶籽多肽的开发应用奠定了一定的理论基础。     

酶法水解油茶籽粕制备油茶籽多肽的研究

以冷榨脱脂油茶籽粕为原料,采用胃蛋白酶水解法对油茶籽多肽的制备条件进行了研究.在单因素试验基础上,应用正交试验确定胃蛋白酶水解油茶籽粕制备油茶籽多肽的最佳工艺条件为:酶解温度40 ℃,酶解时间3 h,加酶量15 000 U/g,固液比1:30.在此最优条件下进行验证试验,油茶籽多肽产率达到61.8%.     

酶法制备米糠多肽的研究

研究了不同蛋白酶以及加酶量、酶解温度、酶解时间、pH对米糠多肽产率的影响,并利用响应面法对米糠多肽制备工艺条件进行了优化,同时分析了木瓜蛋白酶酶解米糠蛋白产物的相对分子质量。结果表明,木瓜蛋白酶是较好的米糠蛋白降解酶,木瓜蛋白酶酶解制备米糠多肽的最优工艺条件为:加酶量1.5%,酶解时间3.4 h,酶解温度40.5℃,pH 5.6;在最优工艺条件下,米糠多肽产率达到79.3%。米糠多肽的相对分子质量分布在500~700之间。     

响应面优化脱酚棉籽粕制备棉籽多肽研究

棉籽粕经脱棉酚处理后,不经过提取棉籽蛋白的中间步骤,直接利用碱性蛋白酶酶解制备棉籽多肽。在单因素实验的基础上,选取酶解温度、酶解pH、加酶量、酶解时间为影响因素,应用响应面法的Box-Behnken中心组合实验进行设计,以棉籽多肽产率为响应值,对制备条件进一步优化。结果表明,采用响应面法得到的最佳制备工艺条件为:酶解温度56.4℃,酶解pH 9.7,加酶量8.4%,酶解时间4.1 h,底物浓度3%,此时的棉籽多肽产率为49.60%。     

液压压榨澳洲坚果粕酶解制备多肽工艺优化

以液压压榨澳洲坚果粕为原料,分析了其常规营养成分含量与氨基酸组成。采用碱性蛋白酶与中性蛋白酶催化酶解澳洲坚果粕蛋白制备多肽。以水解度为指标,利用单因素试验与正交试验考察了各因素对澳洲坚果粕蛋白水解度的影响。结果表明：液压压榨澳洲坚果粕中含有32.25%的蛋白质,17 种氨基酸,含量为25.05%。碱性蛋白酶各因素对澳洲坚果粕蛋白水解度影响的主次顺序为：酶解时间＞酶解温度＞加酶量＞酶解pH值＞底物质量浓度,最佳工艺条件为：酶解温度60 ℃、酶解时间3.5 h、底物质量浓度110 g/L、酶解pH 8.0、加酶量2 400 U/g,在此条件下水解度达到了22.83%。中性蛋白酶各因素影响水解度的主次顺序为：加酶量＞酶解时间＞底物质量浓度＞酶解温度＞酶解pH值,最佳工艺条件为酶解温度55 ℃、酶解时间3.5 h、底物质量浓度100 g/L、酶解pH 7.0、加酶量3 200 U/g,水解度达到了22.78%。碱性蛋白酶与中性蛋白酶各因素对澳洲坚果粕蛋白水解度的影响均达到了极显著水平（P＜0.01）。在最佳工艺条件下,碱性蛋白酶酶解液压压榨澳洲坚果粕制备多肽的效果优于中性蛋白酶。     

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.     

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.     

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.     

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.