油茶饼提取物抗氧化作用及抑菌效果的研究

用含水甲醇对油茶饼进行浸提、过滤和浓缩处理后,将其浓缩液继续进行梯度沉淀,并对梯度沉淀提取物进行定性研究和清除DPPH·自由基活性、抑菌活性的研究。结果表明,梯度沉淀物中含有缩合单宁物质、黄酮类化合物和皂甙等功能性成分,其中缩合单宁物质、黄酮类化合物具有清除DPPH·自由基和抑菌的活性。     

沙棘籽原花色素与葡萄籽原花青素抗氧化活性的比较

采用DPPH·、O2^-、和HO·的清除试验及卵磷脂脂质体氧化试验，研究比较了沙棘籽原花色素和葡萄籽原花青素的抗氧化活性。结果表明：两种原花色素对DPPH·、O2^-·和HO·均具有较强的清除能力；沙棘籽原花色素对O2^-的清除速率和清除活力及对HO·的清除活力显著高于葡萄籽原花青素，对O2^-的半清除浓度分别为23．95μg／mL，与HO·反应的速率常数分别为1．355×10^9L／g·s。两种原花色素均可显著延长AAPH诱导的卵磷脂脂质体氧化的延迟期时间、降低延迟期和扩增期氧化速率，沙棘籽原花色素抑制氧化的效果强于葡萄籽原花青素。     

微波辅助法提取火龙果果皮色素及其功能活性研究

优化火龙果果皮色素的微波辅助法提取工艺,并对色素的功能特性进行初步研究。以火龙果果皮为原料,在单因素实验的基础上,采用正交实验设计对火龙果果皮色素的提取工艺进行优化,并研究了真空干燥色素的抗氧化活性和抑菌活性。结果表明:在料液比1∶50 (g/mL)、乙醇浓度20%、微波功率440 W、微波处理时间60 s的条件下,火龙果果皮色素的提取效果最佳,色素得率为1.074%;2~10 mg/mL提取物对羟自由基(·OH)、超氧阴离子自由基(O₂-·)和DPPH·均具有清除作用,其中对O₂-·的清除效果最好,比V_C的清除效果略低;提取物对大肠杆菌的最低抑菌浓度为1.25 mg/mL,最低杀菌浓度为2.5 mg/mL,抑制效果最好,其次金黄色葡萄球菌、副溶血弧菌、志贺氏菌和蜡状芽孢杆菌。本研究优化了微波辅助提取火龙果果皮色素的工艺条件,所得提取物有较好的抗氧化活性,且对常见食源性病原菌有较强的抑菌活性。     

鱼鳞中糖缀合物的体外抗氧化活性研究

探索了利用碱浸提和酶法去蛋白从淡水鱼鳞中提取糖缀合物的技术，对提取物初步分析后，进行体外抗氧化活性研究。结果表明：鱼鳞糖缀合物对DPPH·O2·^-·OH有较强的清除能力，同时也有较好的还原能力和抗脂质过氧化能力，且与其浓度成正相关。     

蛋白质与还原糖美拉德反应产物的抗氧化活性

本实验采用酪蛋白和大豆分离蛋白同还原糖发生美拉德反应,研究其美拉德反应产物的抗氧化活性,测定了还原力、DPPH·和·OH的清除作用、对脂质体过氧化的抑制能力。结果表明,酪蛋白与还原糖反应得到的美拉德反应产物还原力、对脂质体过氧化的抑制能力、自由基清除能力均高于大豆分离蛋白制备的美拉德反应产物。美拉德反应产物的抗氧化活性同反应物浓度和反应时间存在一定的量效关系,随着反应物浓度的增加,由酪蛋白制备的美拉德反应产物的还原力、·OH、DPPH·清除能力增加,对脂质体过氧化的抑制率先增加后减小。在相同的反应物浓度下,美拉德反应产物抗氧化性随反应时间的增加而增强。     

金莲花黄色素抗氧化与抑菌活性的研究

研究金莲花黄色素的抗氧化与抑菌活性,为其综合利用提供科学依据。实验以清除DPPH·法和·OH法评价金莲花黄色素抗氧化活性,以滤纸片法测定其抑菌活性。抗氧化实验结果显示,金莲花黄色素对DPPH·和·OH的清除率与其质量浓度呈明显的量效关系,其对DPPH·和·OH的半清除率IC_(50)分别为18.04μg/m L和21.35μg/m L;常用抗氧化剂BHT对DPPH·和·OH的半清除率IC_(50)分别为30.18μg/m L和27.96μg/m L。抑菌实验结果显示,当金莲花黄色素质量浓度为0.2 mg/m L时,对金黄色葡萄球菌、枯草芽孢杆菌和大肠杆菌的抑菌圈直径分别可达14.4mm、12.3mm和9.5mm。结果表明,金莲花黄色素具有较强的抗氧化活性和一定的抑菌活性。金莲花黄色素是一种天然抗氧化剂的新资源。     

染料木素及其乳糖苷清除自由基能力的研究

采用DPPH法、Fenton反应．邻二氮菲．Fe2＋光度法和邻苯三酚自氧化法,测定染料木素及其乳糖苷修饰物清除DPPH·、·OH和O2-·能力。结果表明,染料木素及其乳糖苷修饰物清除DPPH·和·OH能力的顺序为：染料木素7,4＇-二-O-β—D-吡哺乳糖苷〉染料木素4＇-O-β-D-毗喃乳糖苷〉染料木素7--O-β-D-吡哺乳糖苷〉染料木素：相反,在低浓度时,染料木素清除O2·的能力强于其乳糖苷修饰物,除染料木素和染料木素7-O-β-D-吡喃乳糖苷对O2·有弱抑制作用外,其他两种乳糖苷对邻苯三酚的自氧化速率均呈现负抑制,且随样液浓度的增加,抑制率降低。     

罗非鱼鱼皮多肽(TSP-I)抗氧化活性的研究

利用化学发光法检测了罗非鱼鱼皮多肽（TSP—I）对超氧阴离子（O2·^-）自由基的清除能力，利用分光光度法检测其清除二苯代苦味酰自由基（DPPH·）的能力，采用Na2S2O3-I2滴定法测定了其抗油脂氧化的能力。实验发现：罗非鱼鱼皮多肽对二苯代苦味酰自由基的抑制作用强于对超氧阴离子自由基的抑制作用，其清除两种自由基50％所对应的质量浓度（IC50）分别为：13，96mg／mL和16，79mg／mL。添加罗非鱼鱼皮多肽对油脂具有良好的抗氧化作用，其中以添加1．00％的鱼皮多肽抗氧化效果最佳，另外Vc对鱼皮多肽具有协同抗氧化作用，效果优于单独添加0．05％和0．20％鱼皮多肽。     

苏芳花花色素体外抗氧化性及抑菌性研究

从苏芳花鲜花瓣提取分离花色素,研究其在体外的抗氧化性和抑菌性。结果表明:苏芳花花色素具有较强的还原性,能有效清除系统中的超氧阴离子和羟基自由基,且清除效果与色素浓度正相关。在苏芳花花色素浓度为0.48 mg/mL时,其还原力与0.1 mg/mL VC相当,而对超氧阴离子和羟基自由基的清除率则可分别达到59.3%和96.1%。苏芳花花色素能够显著抑制大肠杆菌、金黄色葡萄球、枯草芽孢杆菌的生长。在色素浓度为0.48 mg/mL时,对3种菌的抑菌圈直径分别为9.46 mm、9.36 mm和8.14mm。苏芳花花色素具有较强的抗氧化性和抑菌性。     

樟树果实红色素的抑菌活性

从樟树果实中提取红色素,检测该色素的抑菌活性及稳定性。结果表明,樟树果实红色素对大肠杆菌、金黄色葡萄球菌和痢疾杆菌的生长有较强的抑制活性,最小抑菌浓度(MIC)分别为4.0mg/mL、1.0mg/mL和3.0mg/mL;该色素经酸、碱、热处理后仍具有较强的抑菌活性;0.1mol/L的Zn2+及0.1mg/mL的淀粉、葡萄糖对该色素的抑菌活性影响较小,0.1mol/mL的Cu2+、Fe3+、Ca2+、Na+等均具增效作用。食品防腐实验表明,该色素有较好的食品防腐作用。     

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.     

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.     

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.     

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.