酶解王米蛋白粉制备抗氧化肽

以玉米蛋白粉为原料,2709碱性蛋白酶为水解酶,采用正交实验设计优化水解条件,用NBT法和D2-脱氧核糖法测定水解所得玉米肽的抗氧化活性.结果表明,制备玉米抗氧化肽的最佳酶解条件为pH9.5,[E]/[S]=10%,时间4h,温度55℃,该条件下制备的玉米抗氧化肽对O2-·和·OH有很强的清除作用,清除率分别为54.42%和82.31%.     

酶法制备家蝇幼虫抗氧化肽条件的优化

以家蝇幼虫为原料,Alcalase碱性蛋白酶为水解酶,采用五因子二次旋转正交组合设计优化水解条件,用清除DPPH·活性的方法测定水解所得家蝇幼虫肽的抗氧化活性.结果表明,制备家蝇幼虫抗氧化肽的最佳酶解条件为:[E]/[S]=3.62%、温度62.17℃、pH 8.20、底物浓度11.71%、时间3.05h.在该水解条件下家蝇幼虫抗氧化肽对DPPH·有很强的清除作用,清除率为86.387%.     

扇贝裙边酶解液抗氧化性研究

为研究扇贝裙边酶解条件以及酶解产物的抗氧化性,选取碱性内切蛋白酶、中性蛋白酶、木瓜蛋白酶、As1.398中性蛋白酶、复合蛋白酶和复合风味蛋白酶对扇贝裙边进行水解,制取抗氧化活性肽.通过亚油酸-硫氰酸钾法和邻苯三酚法测定酶解物的抗氧化活性筛选蛋白酶,确定水解的最适时间并进行单因素实验.进行正交实验,确定蛋白酶水解扇贝裙边的最佳条件,选择最佳蛋白酶.将其抗氧化活性与Vc、BHT、BHA比较.研究结果表明:筛选出抗氧化活性较高碱性内切蛋白酶,水解时间1.5 h.正交实验结果为碱性内切蛋白酶的最优水平为T=60℃,pH:7,[S]=12%,[E]/[S]=11%;抗氧化率为63.94%和40.58%.经过比较,碱性内切蛋白酶水解物的抗氧化性与抗氧化剂Vc、BHT、BHA的抗氧化效果接近.     

酶解玉米蛋白粉制备抗氧化肽

以玉米蛋白粉为原料,2709碱性蛋白酶为水解酶,采用正交实验设计优化水解条件,用NBT法和D2-脱氧核糖法测定水解所得玉米肽的抗氧化活性。结果表明,制备玉米抗氧化肽的最佳酶解条件为:pH9.5,E/S=10%,时间4h,温度55℃,该条件下制备的玉米抗氧化肽对O2-·和·OH有很强的清除作用,清除率分别为54.42%和82.31%。     

秘鲁鱿鱼皮明胶抗氧化肽的制备及其分子质量分布

目的:基于鱿鱼皮明胶肽的抗氧化活性,优化制备工艺,探究其分子质量分布。方法:分别使用4种蛋白酶水解鱿鱼皮明胶,通过测定体外抗氧化活性来确定最适水解用酶。以DPPH自由基清除率为指标,利用单因素及响应面法优化明胶抗氧化肽的制备工艺,通过Tricine-SDS-PAGE及Sephadex G-25凝胶过滤层析测定明胶肽的分子质量分布。结果:碱性蛋白酶为最适水解用酶,最适水解温度55℃,酶添加量7 000 u/g(E/S),时间109 min,底物明胶质量分数6%,pH 6.66。此条件下明胶肽的DPPH自由基清除率达93.18%。90%明胶肽的分子质量介于1.4~10 ku之间。     

中性蛋白酶水解螺旋藻制备抗氧化肽的工艺研究

试验研究了采用中性蛋白酶水解螺旋藻制备抗氧化性肽的最佳工艺。将螺旋藻破壁离心后,用中性蛋白酶水解,以·OH清除率、DPPH·清除率和总还原力为评价指标,在单因素试验基础上,进行了正交试验,确定了最佳酶解工艺条件。试验结果表明,中性蛋白酶水解螺旋藻制备抗氧化肽的最佳工艺条件为:酶解温度为60℃、[E]/[S]为3%、p H为7.3,时间为4 h。此条件下螺旋藻中性蛋白酶的水解物的·OH的清除率是92.790%、DPPH·的清除率为18.941%,代表总还原力大小的吸光度为1.507。     

复合酶法制备鸡肉蛋白抗氧化肽模型研究

以酶解产物对O2-·的清除率为指标,分析中性蛋白酶和未瓜蛋白酶的协同作用,确定制备鸡肉蛋白抗氧化肽的最佳复合酶解工艺,并对复合酶解过程进行酶促动力学特性研究.结果表明:复合酶解制备抗氧化肽最佳工艺为两酶混合同时加入,pH6.7,温度57℃,底物浓度6.9%,时间5h,酶用量为中性蛋白酶4943u/g、木瓜蛋白酶5988u/g,该条件下鸡肉蛋白抗氧化肽对O2-·的清除率为57.50%,显著高于各单酶水解效果.在此基础上由实验数据推导出描述复合酶制备鸡肉蛋白抗氧化肽水解过程的动力学方程,为鸡肉蛋白开发抗氧化肽提供理论依据.     

Alcalase蛋白酶水解花椒籽蛋白制备抗氧化肽的条件优化

本研究以花椒籽蛋白质抗氧化肽水解度(DH)和DPPH自由基清除率为指标,对酶解花椒籽蛋白制备抗氧化肽的水解用酶及其酶用量、底物浓度、酶解温度、时间等酶解条件进行研究,以期优化得到酶解法制备花椒籽抗氧化肽的最优条件。结果表明Alcalase蛋白酶水解花椒籽蛋白制备抗氧化肽效果最好,通过响应面分析法优化出该酶最佳酶解花椒籽制备抗氧化肽的条件为:底物浓度5%,温度55℃,pH 8.5,加酶量4%;该方法可用于花椒籽蛋白制备抗氧化肽,在此条件下花椒籽水解液DPPH自由基清除率可达到61.00%,水解度为12.00%。     

酶法水解滑菇蛋白制备抗氧化肽的工艺优化

本文研究了酶法水解滑菇蛋白制备抗氧化肽的工艺条件,通过水解度与羟自由基(·OH)清除率来综合评价水解产物的抗氧化能力。以·OH清除率为指标,从碱性蛋白酶、中性蛋白酶、风味蛋白酶、木瓜蛋白酶和胰蛋白酶5种蛋白酶中筛选最适酶。在单因素实验研究酶浓度、底物浓度与水解时间对酶解产物·OH清除率和水解度影响的基础上,通过L_9(4~3)正交实验对水解工艺进行优化。结果得出,碱性蛋白酶活力高于其他4种蛋白酶,能使蛋白质充分水解,正交实验各因素对水解产物·OH清除率的影响程度依次为底物浓度酶浓度水解时间。其中,碱性蛋白酶的最佳水解工艺条件为:底物浓度3.0%、酶浓度3500 U/g、p H9.0、温度55℃、水解时间3.5 h。在此条件下,水解产物的·OH清除率可达82.7%,水解度为23.1%。碱性蛋白酶水解滑菇蛋白制备抗氧化肽的工艺可行,为滑菇蛋白高附加值产品的开发提供技术参考。     

扁杏仁抗氧化肽的制取工艺研究

研究了扁杏仁抗氧化肽的酶解制备工艺及其体外抗氧化活性。以羟基自由基的清除率和水解度为考察指标,用响应面分析法研究酶用量、底物浓度、温度和p H对扁杏仁抗氧化活性肽酶解工艺的影响。得出优化后的酶解条件为:碱性蛋白酶-风味蛋白酶的复合酶用量6725 U/g(碱性蛋白酶为3645 U/g,风味蛋白酶为2690 U/g)、底物质量分数为3%、温度60℃、p H8.28,在该条件下制备的扁杏仁抗氧化活性肽对羟基自由基的清除率和水解度分别为84.18%和20.87%。     

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.     

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.     

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.     

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.     

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.