预分离米糠蛋白类阿片拮抗肽的离子交换工艺

研究离子交换层析法对米糠蛋白酶解物超滤透过液中类阿片拮抗肽的初步分离提取。采用强酸性阳离子交换树脂,上样流速:SV0.8,上样pH值:5.0;洗脱液氨水浓度:1mol/mL,洗脱速度:SV1.2。离体豚鼠回肠(GPI)检定法鉴定表明,在此条件下制备的米糠蛋白类阿片拮抗肽活性得到提高。     

米糠类阿片拮抗肽的氨基酸序列分析

采用氨基酸分析仪、LC-MS对米糠类阿片拮抗肽的结构进行了分析，米糠类阿片拮抗肽由Asp、Gly、Ser、Val和Arg组成，它的氨基酸序列为Asp-Gly-Ser-Val-Arg。     

利用米糠蛋白制备类阿片拮抗肽和降血压肽的研究

采用离体豚鼠回肠(GPI)检定法测定不同米糠蛋白胰蛋白酶水解物的类阿片拮抗活性,结果发现跟新鲜米糠一样,低温脱脂米糠蛋白的酶解物具有较高的类阿片拮抗活性,高温脱脂米糠蛋白的酶解物无类阿片拮抗活性。采用低温脱脂米糠蛋白为原料,研究其制备类阿片拮抗肽后的残留蛋白酶解物的ACE抑制活性,结果发现在6种酶解物中,水解度(DH)为15.4%的碱性蛋白酶水解物的ACE抑制活性最高。     

玉米胚芽蛋白酶解物的超滤工艺研究

采用超滤法探索了玉米胚芽蛋白酶解物中初步分离小肽的生产工艺,研究了料液浓度、操作压力、温度、时间对膜通量的影响,并利用高效凝胶过滤色谱(HPSEC)比较了超滤前后酶解物的分子量分布。结果表明:最佳操作条件为料液浓度15mg/mL、操作压力0.5MPa、温度25℃、超滤时间150min,超滤能够有效地将粗酶解液中未被水解的蛋白和高分子量的多肽去除。     

减压膜蒸馏浓缩NaCl溶液的实验研究

采用减压膜蒸馏技术在较低真空度下浓缩NaCl水溶液 ,研究了真空度、料液温度、料液流速以及料液浓度对膜通量与截留率的影响。结果表明 ,随着膜下游真空度增加 ,膜通量线性增大 ;料液温度显著影响膜通量 ;随着料液浓度增加 ,膜通量严重衰减 ;实验条件下聚丙烯中空纤维膜表现出很好的疏水性 ,NaCl的截留率接近 10 0 %。     

大豆低聚肽的膜分离研究

本研究选用分子量1000的超滤膜来分离大豆低聚肽,分别研究了料液原始浓度、时间、压力、膜阻力、膜效能等对超滤的影响,确定在料液浓度0.2%、ΔP=0.32MPa的条件下,超滤效果最佳,低聚肽的得率为55.6%。     

几种常见植物蛋白生物活性肽的研究概述

对大豆、大米、小麦、玉米四种植物蛋白的生物活性肽进行了介绍，主要包括：降血压肽、阿片样活性肽、类阿片样拮抗肽、免疫调节肽等。这些活性肽的发现为今后进一步利用植物蛋白资源，生产功能性食品基料或药品提供了一条新途径。     

乳源性促矿物元素吸收肽超滤技术的优化

采用超滤技术,对通过胰蛋白酶酶解制备的粗肽进行初步分离纯化,从而获得较高纯度的促矿物元素吸收肽。对超滤工艺中几个主要技术参数(超滤压力、料液初始稀释倍数、料液pH 值、料液温度)进行了研究,以膜通量、目标肽回收率和P/N(摩尔比)作为其结果的评价指标。结果表明：利用截留分子量为6000D 的中空纤维超滤膜,在超滤压力为0.125MPa、料液初始稀释倍数为4、料液pH5.5、料液温度45℃的条件下,以45min 作为一个超滤周期,能得到纯度最高和活性最大的促矿物元素吸收肽。该条件下获得的目标肽可以将NaH2PO4 和CaCl2 在体外产生沉淀的时间推迟15min,此时目标肽回收率为84.1%。     

减压膜蒸馏浓度NaCl溶液的实验研究

采用减压膜蒸馏技术在较低真空度下浓缩NaCl水溶液，研究了真空度，料液温度，料液流速以及料液浓度对膜通量与截留率的影响。结果表明，随着膜下游真空度增加，膜通量线性增大；料液温度显著影响膜通量；随着料液浓度增加，膜通量严重衰减；实验条件下聚丙烯中空纤维膜表现出很好的疏水性，NaCl的截留率接近100%。     

减压膜蒸馏用于纤维素溶剂N-甲基吗啉-N-氧化物浓缩回收研究

为解决纤维素绿色溶剂N-甲基吗啉-N-氧化物(NMMO)传统浓缩回收工艺存在的能耗高、回收率低等不足,提出基于减压膜蒸馏(VMD)技术的NMMO浓缩回收方法。通过考察VMD过程中真空度、料液流速、料液温度、料液浓度对膜蒸馏过程的影响,并对深度浓缩的可行性和体系运行稳定性进行研究。结果表明:膜蒸馏通量随真空度、料液流速、料液温度的增大而增大,随料液浓度的增大而减小,产水浓度随真空度的增大而减小,而料液流速、料液温度、料液浓度对产水浓度影响不明显;采用VMD过程可成功将初始质量浓度为100 g/L的NMMO溶液浓缩至467.2 g/L,体系在连续5个浓缩周期共60 h的运行过程中,保持了较好的运行稳定性,对NMMO的截留率始终保持在99.88%以上。所提方法具有良好的技术可行性。     

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.     

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.     

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.     

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.