不同类胡萝卜素清除自由基能力的比较

比较不同结构类胡萝卜素清除自由基能力。分别以虾青素、β-胡萝卜素、番茄红素和叶黄素为对象,采用DPPH法、水杨酸法和邻苯三酚自氧法分别表征清除DPPH·自由基、羟基自由基和超氧阴离子自由基能力。结果表明类胡萝卜素具有较强的清除自由基能力,且清除能力均遵循剂量-效应关系;对DPPH·自由基、羟基自由基和超氧阴离子的清除能力大小关系为虾青素叶黄素β-胡萝卜素番茄红素。类胡萝卜素清除自由基能力优良,不同结构类胡萝卜素清除自由基能力有差异,此类功能性产品具有广阔的市场前景。     

猕猴桃根提取物体外抗氧化作用的研究

探讨猕猴桃根提取物的体外抗氧化作用.采用DPPH自由基、超氧阴离子、羟基自由基、过氧化氢和还原力的反应体系,测定猕猴桃根提取物的体外抗氧化作用,并用VC进行对照实验.实验条件下,ERHM对DPPH自由基、超氧阴离子(·O2-)、羟基自由基(·OH)、过氧化氢H2O2等均有较强的清除或抑制作用,且显示较好的量效关系,同时具有一定的还原力.其消除DPPH自由基的EC50为8.03 μg/mL,清除超氧阴离子(·O2-)的EC5o为1.28 mg/mL,抑制羟基自由基(·OH)能力可达69.4％,浓度为100 μg/mL时对过氧化氢(H2O2)的清除率为42％.猕猴桃根提取物具有较强的还原力,能有效清除DPPH和超氧阴离子自由基,并抑制羟基自由基的产生.所以,ERHM有效成分具有较为显著的抗氧化作用.     

首乌叶黄酮抗氧化性能及清除自由基能力的研究

测定了首乌叶黄酮的总体抗氧化能力、清除超氧阴离子自由基能力、清除羟基自由基能力、清除DPPH自由基能力和对卵黄脂蛋白脂质抗氧化能力,并与合成抗氧化剂维生素C(VC)和没食子酸丙酯(PG)进行了比较。结果表明:首乌叶黄酮溶液具有良好的抗氧化效果,在一定浓度范围内,首乌叶黄酮溶液对卵黄脂蛋白脂质抗氧化能力优于VC和PG,其总体抗氧化能力、清除超氧阴离子自由基能力优于PG略低于VC,清除羟自由基能力优于VC低于PG,但清除DPPH自由基能力比VC和PG略弱。     

玉米多肽抗氧化作用的研究

用K3[Fe(CN)6]测定了玉米多肽的还原力;采用脱氧核糖一铁体系、超氧阴离子自由基体系、二苯代苦味肼基自由基(DPPH·)体系对玉米多肽的抗氧化活性进行了研究,并同VC进行了比较.结果表明玉米多肽具有还原力.玉米多肽对这几种自由基均有不同程度的清除作用,其中在20～50 mg/mL清除羟基自由基能力与VC相差不大;玉米多肽清除DPPH·和O2-·的能力均低于VC,玉米多肽5 mg/mL时,DPPH·清除率接近57.59%,10 mg/mL时,O2-·清除率为46.05%.     

槲树叶黄酮的抗氧化特性研究

以槲树叶为原料,从DPPH自由基清除能力﹑总还原力、羟基自由基清除能力﹑抗亚油酸氧化能力及超氧阴离子清除能力五个方面研究槲树叶黄酮的抗氧化活性,同时与VC﹑BHT进行比较。结果表明:在实验条件下,槲树叶黄酮的抗氧化能力随浓度的升高而增大,对DPPH自由基清除能力和总还原力强于VC、BHT。对羟基自由基清除能力和抗亚油酸氧化能力弱于VC和BHT。对超氧阴离子清除能力在高浓度时优于VC和BHT。     

襄荷中黄酮类化合物的抗氧化性研究

以襄荷为原料,利用超声波辅助乙醇法提取襄荷中的黄酮类化合物。通过测定DPPH自由基清除率、超氧阴离子清除率、羟基自由基清除率及其在菜籽油中的过氧化值(POV)评价襄荷花苞中黄酮类化合物的抗氧化活性。结果证明,襄荷花苞中黄酮类化合物有一定的清除DPPH·、O_2~—·和羟基自由基的能力,当襄荷花苞黄酮提取液浓度达到0.705 mg/mL时,其对DPPH·和超氧阴离子清除率分别达到98.7%和99.3%,与提取液质量浓度成正比。在菜籽油中与Vc具有协同作用,且抗氧化能力与襄荷花苞中黄酮类化合物含量呈正比。     

树舌胞内多糖抗氧化活性的研究

目的:探讨树舌胞内多糖(GAPS)体外抗氧化作用.方法:从清除超氧阴离子自由基、抑制羟基自由基的产生、清除DPPH自由基和还原力4个方面,研究了树舌胞内多糖的体外抗氧化效果.结果:树舌胞内多糖有较强的还原力,并在体外对超氧阴离子自由基(O-2·)、羟基自由基(·OH)、DPPH有机自由基有较强的清除作用.树舌胞内多糖浓度为1.0mg/mL时,其清除O-2·能力为36.36%;对于·OH,在浓度为2.5mg/mL时,清除率达到56.97%;对于DPPH·,在浓度为1.0mg/mL时,清除率达到45.31%;当树舌胞内多糖浓度为0.5mg/mL时的还原能力与0.03mg/mLVc,相当.结论:树舌胞内多糖具有抗氧化方面的应用开发前景.     

海金沙黄酮体外抗氧化活性研究

目的:研究海金沙黄酮(Flavones from Lygodiu mjaponicum,FLJ)的制备与体外抗氧化活性。方法:通过回流法萃取和大孔吸附树脂纯化,得到纯化的FLJ。以VC、BHT、芦丁和槲皮素为阳性对照,对羟基自由基、超氧阴离子自由基、烷基自由基的清除率以及抑制油脂过氧化的能力进行研究。结果:FLJ对上述自由基均有一定的清除作用,对羟基自由基、超氧阴离子自由基清除能力弱于VC、芦丁和槲皮素;对油脂抗氧化作用强于BHT和VC。浓度为1.04mg/mL的FLJ和VC对烷基自由基的清除能力相当。FLJ的添加量在实验范围内与其抗氧化活性呈正相关。结论:FLJ具有明显的体外抗氧化活性。     

牛骨股原蛋百肽体外清除自由基活性的研究

对经碱性蛋白酶Alcalase 2.4L水解的牛骨胶原蛋白肽清除自由基活性进行了研究。根据对羟基自由基、超氧阴离子自由基、二苯代苦味酰基自由清除能力的测定,以及还原能力、脂质抗氧化能力等抗氧化活性指标的测定,确定了水解度为7.9%左右的胶原蛋白肽清除自由基的综合效果最好,此时酶解产物的平均分子量为2025Da,含15个左右的氨基酸。在此条件下,超氧阴离子(O2-·)的清除率为63.86%,羟基自由基(·OH)的清除率为99.55%,二苯代苦味酰基自由基(DPPH·)的清除率为27.03%,对大豆卵磷脂过氧化作用的抑制率为74.78%。     

牛骨胶原蛋白肽体外清除自由基活性的研究

对经碱性蛋白酶Alcalase 2.4L水解的牛骨胶原蛋白肽清除自由基活性进行了研究。根据对羟基自由基、超氧阴离子自由基、二苯代苦味酰基自由清除能力的测定,以及还原能力、脂质抗氧化能力等抗氧化活性指标的测定,确定了水解度为7.9%左右的胶原蛋白肽清除自由基的综合效果最好,此时酶解产物的平均分子量为2025Da,含15个左右的氨基酸。在此条件下,超氧阴离子(O2-·)的清除率为63.86%,羟基自由基(·OH)的清除率为99.55%,二苯代苦味酰基自由基(DPPH·)的清除率为27.03%,对大豆卵磷脂过氧化作用的抑制率为74.78%。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.