罗非鱼皮明胶酶解物及其模拟消化产物的抗氧化活性

以罗非鱼皮为原料提取罗非鱼皮明胶,选用风味蛋白酶和胰蛋白酶制备罗非鱼皮明胶酶解物,采用ABTS自由基、DPPH自由基、羟基自由基及亚油酸过氧化体系,初步评价罗非鱼皮明胶酶解物的抗氧化活性,再通过模拟体外胃肠道消化实验,结合分子质量分布测定,进一步考察罗非鱼皮明胶酶解物的抗氧化活性。结果显示,在酶解过程中,风味蛋白酶及胰蛋白酶酶解的水解度逐渐升高,在3 h时达到最高,分别达到5.8%和25.36%。在酶解60 min时其TCA可溶性肽得率最高,风味蛋白酶、胰蛋白酶酶解物分别达56.82%和54.44%。通过比较半抑制浓度(IC_50),确定了酶解60 min时风味蛋白酶酶解物的清除DPPH自由基及抑制亚油酸过氧化能力较胰蛋白酶酶解物强。模拟体外胃肠道消化后,酶解物羟基自由基清除活性均显著提高(p0.05),亚油酸脂质过氧化活性明显降低,消化前后样品分子量分布范围均主要集中于3000~5000 Da,消化后风味蛋白酶及胰蛋白酶酶解物3000~5000 Da组分的含量分别提高了45%及13%。以上研究结果表明,罗非鱼皮明胶酶解后制备的明胶水解物具有一定的抗氧化能力,具有潜在的开发价值。     

生物解离大豆蛋白酶解物体外模拟消化抗氧化活性变化

挤压膨化大豆在生物解离过程中,通过酶解（碱性蛋白酶、风味蛋白酶）产生的大豆蛋白酶解物（soybean protein hydrolysate,SPH）有良好的抗氧化活性,因此,需要探索模拟胃肠道（gastrointestinal,GI）消化对蛋白酶解物抗氧化活性的影响。分别以蛋白酶（碱性蛋白酶、风味蛋白酶）酶解得到的SPH和经过模拟GI消化后的产物作为研究对象,采用水解度、氨基酸组成、分子质量分布、氧化自由基吸收能力（oxidative radical absorption capacity,ORAC）、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力及2,2’-联氨-双(3-乙基苯并噻唑啉-6-磺酸)（2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt,ABTS）阳离子自由基清除能力对样品抗氧化活性进行分析。结果显示：相对于风味蛋白酶酶解,采用碱性蛋白酶进行酶解时抗氧化活性更高;但是经过模拟GI消化后,风味蛋白酶酶解得到的SPH抗氧化活性更高,ORAC为69.15 μmol/mg、DPPH自由基清除能力为27.29%、ABTS阳离子自由基清除能力为56.21%,肽的相对含量更高,为75.86%,并且肽中具有抗氧化活性的氨基酸含量更高,分子质量小于1 kDa的肽相对含量最高,为17.35%。     

岩藻黄质的抗脂质氧化活性研究

以岩藻黄质为原料,研究岩藻黄质对鱼油和猪油的抗氧化活性。结果表明,岩藻黄质在氧化模型中能有效抑制鱼油以及猪油中丙二醛（MDA）的生成,与空白组相比最高抑制率达到78.1%和80.9%。采用电子自旋共振波谱技术,研究岩藻黄质对鱼油、玉米油、亚油酸、亚油酸盐模型中脂质自由基的清除作用,当岩藻黄质质量浓度达100 ng/mL,加速氧化3 h时,鱼油模型与玉米油模型中脂质自由基的抑制率分别为（64.46 ± 6.46）%和（57.4 ± 5.15）%;当岩藻黄质质量浓度为300 ng/mL,加速氧化10 min时,亚油酸模型与亚油酸盐模型中,脂质自由基抑制率分别为（75.24 ± 7.32）%和（66.9 ± 1.06）%。该研究为岩藻黄质在食品抗氧化剂领域的应用提供了一定的理论依据。     

玉米活性肽的分离纯化及抑制体外脂质过氧化作用研究

以玉米醇溶蛋白为底物,利用碱性蛋白酶进行水解反应获得了玉米活性肽组分,经离子交换和葡聚糖凝胶等方法对产物进一步分离纯化。以H2O2及Fe2+诱导的小鼠体外脂质过氧化反应为靶点,研究了玉米活性肽及其分离纯化组分对脂质过氧化的抑制作用。结果表明:活性肽及其分离纯化组分均具有抗脂质过氧化作用,其对小鼠肝组织体外脂质化抑制率达到30.65%。其中组分Ⅰ的抑制活性最强,分子量主要分布在400~1000u。     

干酪乳清水解产物的抗氧化活性研究

选用新鲜干酪乳清为原料,研究碱性蛋白酶对乳清水解产物的抗氧化活性。以水解产物的亚铁还原能力、对卵磷脂脂质氧化体系的过氧化抑制作用、羟自由基清除能力和超氧阴离子自由基的清除能力为指标评价乳清水解产物的抗氧化能力。结果表明,乳清在水解前经过预热处理并不能增加其水解产物的抗氧化活性,1 h水解物的亚铁还原能力最高,2 h水解产物对卵磷脂脂质氧化体系的过氧化抑制作用最高,抑制率达到24.82%;2 h水解产物羟自由基清除率最高,达到70.28%;2 h水解产物超氧阴离子自由基清除率最高,达到21.4%。但是乳清水解产物的抗氧化能力与水解度没有线性关系。     

模拟人胃肠仿生消化对花生肽亚铁抗氧化活性的影响

为探讨花生肽亚铁在模拟人胃肠仿生消化条件下抗氧化活性变化规律,研究了仿生消化过程中表面疏水性、DPPH·清除率、O_2~-·清除率、·OH清除率、亚油酸氧化抑制活性和脂质过氧化抑制活性等指标变化。结果发现:模拟胃肠仿生消化后花生肽亚铁表面疏水性得到增强,仿生消化270 min时表面疏水性最大((15. 84±0. 33)μg);仿生消化增强了DPPH·清除活性,仿生消化300min时,DPPH·清除率为(88. 77±1. 00)%,显著高于1. 0 mg/mL V_C(p 0. 05);胃肠仿生消化物O_2~-·和·OH清除活性分别显著低于1. 0 mg/mL V_C和0. 6 mg/mL V_C;胃肠仿生消化物具有较好的亚油酸氧化抑制作用,小肠仿生消化物抑制活性最高;仿生消化可增强脂质过氧化的保护效果,仿生消化330 min(质量浓度20 mg/L)时,脂质过氧化抑制效果最好,但显著低于V_C对脂质过氧化的抑制作用(p 0. 05)。试验结果表明,胃肠仿生消化可不同程度地增强花生肽亚铁的抗氧化活性。     

乳清蛋白肽美拉德反应产物的优化制备及其抗氧化活性

以乳清蛋白碱性蛋白酶水解物为原料与葡萄糖发生美拉德反应,通过单因素试验和响应面耦合遗传算法优化制备乳清蛋白肽美拉德反应产物（whey protein peptides Maillard reaction products,WPP-MRPs）,并测定其对 2,2′-连氮基-双-（3-乙基苯并二氢噻唑啉-6-磺酸）二铵盐自由基（ABTS+自由基）和羟基自由基（·OH）的清除能力。结果表明WPP-MRPs制备最优的工艺参数组合为葡萄糖浓度8.3%、反应温度90℃、反应时间4 h和pH9.0,在此条件下WPP-MRPs的还原力为0.93±0.02。在最优工艺条件下制备的WPP-MRPs对ABTS+自由基和羟基自由基清除率的IC50分别为（47.15±0.83）mg/mL和（44.28±0.95）mg/mL。结果显示WPP-MRPs具有较强的抗氧化活性。     

模拟胃肠道消化对玉米低聚肽抗氧化作用的影响

以胃蛋白酶和胰蛋白酶在体外模拟胃肠环境,测定模拟消化前后玉米低聚肽的相对分子质量分布、DPPH自由基清除能力、·OH清除能力、ABTS自由基清除能力、ORAC值和ROS清除能力,旨在探索模拟胃肠道消化对玉米低聚肽抗氧化活性的影响。结果表明：玉米低聚肽中大部分肽段相对分子质量低于1 000。分别模拟胃、肠环境消化后,重均相对分子质量有所下降,下降率分别为1.47%、0.05%,ABTS自由基清除能力有一定程度的升高,分别为25.47%、1.39%。模拟胃环境消化前后,DPPH自由基清除能力IC50值分别约为1.41、1.50 mg/mL,·OH清除能力IC50值分别约为10.3、12.3 mg/mL;模拟肠环境消化前后,DPPH自由基清除能力IC₅₀值分别约为1.39、1.48 mg/mL,·OH清除能力IC₅₀值分别约为8.1、9.5 mg/mL。模拟胃环境消化后,ORAC值有所降低,降幅为10.4%,100、400 μg/mL玉米低聚肽对ROS清除能力分别提高了1.42%、16.78%;模拟肠环境消化后,ORAC值提高了1.4%,100 μg/mL玉米低聚肽对ROS清除能力降低1.71%,而400 μg/mL玉米低聚肽对ROS清除能力提高2.61%。     

松茸水解蛋白肽制备及其抗氧化活性的研究

目的：本文以松茸作为原料经过蛋白提取和蛋白酶解得到蛋白肽,并研究其抗氧化能力。方法：将前期在最优条件下提取的松茸蛋白（得率13.56%）经蛋白酶解,筛选酶及优化酶的组合并制备水解蛋白肽;通过DPPH自由基清除、ABTS自由基清除及羟自由基清除3种自由基清除测定其抗氧化活性。结果：最佳水解酶组合为风味蛋白酶:碱性蛋白酶=1:3,水解工艺为底物浓度6mg.ml-1,作用时间6h,酶添加量2.0%;抗氧化活性实验结果表明水解肽的DPPH自由基清除和ABTS自由基清除能力较强,ABTS自由基清除能力较稳定。结论：深入研究松茸水解蛋白肽并将其应用于食品工业,为食品行业需找新的可利用资源有一定的应用价值。     

玉米抗氧化肽的分离制备及其体外抗氧化活性的研究

本实验以2709碱性蛋白酶水解玉米蛋白粉制备玉米抗氧化肽，SephadexG-25、DEAE52纤维素纯化玉米抗氧化肽，并用几种不同的实验体系研究其体外抗氧化活性。结果表明，玉米抗氧化肽制备的最佳酶解条件为：pH=9．5，[E]／[S]=10％，时间4h，温度55℃。该条件下制备的玉米抗氧化肽对超氧阴离子自由基和羟基自由基有强烈的清除作用，并能显著地抑制细胞和组织脂质过氧化反应的发生（P〈0．01）。氨基酸组成分析表明其富含丙氨酸和亮氨酸，摩尔分数分别为17．39％和13．04％，并且含有5种人体必需的氨基酸，占玉米抗氧化肽氨基酸总含量的39．13％，因此在具有较高生物学活性的同时也具有较高的营养价值。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.