不同分子量水牛乳酪蛋白酶解肽抗氧化活性的研究

通过超滤分离得到不同分子量范围的水牛乳酪蛋白酶解肽组分,对比不同组分的抗氧化活性,结果表明:分子量范围小于1 ku的组分,其DPPH自由基、羟基自由基、超氧阴离子清除能力以及还原能力均高于分子量范围在大于1 ku(1~3 ku)的组分,且二者均显著高于(P0.05)酶解前的底物酪蛋白。     

不同加工工艺乳饼抗氧化肽稳定性研究

为研究不同加工工艺乳饼抗氧化肽的稳定性,以传统乳饼（TRB）和发酵型乳饼(FRB)为实验材料,超滤分离出不同分子量（3～10 ku和<3 ku）乳饼蛋白肽,以ABTS、DPPH自由基清除率、还原能力RP为评价指标,考察温度、pH、食品原辅料、压力等加工环境和模拟胃肠消化对不同工艺乳饼抗氧化活性的影响。结果表明,不同加工环境及模拟胃肠消化后,不同分子量的FRB抗氧化肽稳定性高于TRB,且3～10 ku的FRB抗氧化肽活性最高;FRB和TRB抗氧化肽在高温和酸碱环境中活性显著下降（P<0.05）;山梨酸钾和超高压加工技术对乳饼抗氧化活性影响不显著;高糖抑制抗氧化活性,但分子量3～10 ku的FRB蛋白肽DPPH·清除率任能维持在84%以上;2%～8%的NaCl有利于提高抗氧化活性。胃肠消化后,不同工艺乳饼蛋白肽DPPH自由基清除活性显著降低（P<0.05）,ABTS·清除率、还原能力显著升高（P<0.05）,其ABTS·清除率高于41.85%,还原能力RP值大于0.12。研究可为乳饼及其抗氧化肽的加工利用提供理论依据。     

荸荠皮总黄酮的纯化及其抗氧化活性研究

利用大孔吸附树脂纯化荸荠皮总黄酮,探讨总黄酮的纯化条件,并通过总抗氧化性能试验、ABTS试验和DPPH试验评价了总黄酮抗氧化活性。试验结果表明,用乙醇水溶液梯度洗脱D101大孔吸附树脂,获得纯度高、抗氧化活性好的荸荠皮总黄酮,黄酮收率为58.52%,纯度为70.64%。所得总黄酮具有良好的还原能力,为0.60 mmol TE(Trolox当量)/g,和良好的ABTS·+、DPPH自由基清除活性,IC50分别为1.86、0.49 mmol TE/g,其中ABTS·+自由基清除性能均大于对照物Trolox和芦丁,DPPH自由基清除性能大于芦丁。     

分子量对酪蛋白多肽抗氧化活性的影响

在对酪蛋白酶解产物制备工艺进行优化的基础上,对不同分子量抗氧化肽(>3ku,1～3ku,<1ku)的抗氧化活性进行了评价。首先对酶的种类、酶底物比及水解时间进行了单因素实验,最终确定采用碱性蛋白酶,在pH8.0,55℃,底物浓度5%,酶底物比0.192AU/g的条件下,酶解4h所得水解物抗氧化活性最高。经过超滤和凝胶过滤层析分离获得不同分子量的抗氧化肽,并采用2,2′-连氮基-双-(3-乙基苯并二氢噻唑啉-6-磺酸)二铵盐(ABTS+.)、羟自由基和超氧自由基清除活性评价其抗氧化性。结果表明,ABTS+.清除活性与分子量呈负相关(r=-0.898,p<0.01),分子量低于1ku组分活性最强(2mg/mL,Trolox当量为2.08±0.05mmol/L);分子量低于3ku的抗氧化肽羟自由基清除活性较高(IC50:1～3ku,4.43±0.03mg/mL;<1ku,4.35±0.06mg/mL);分子量高于3ku组分主要分布在3～5ku,超氧自由基清除活最强(10mg/mL,66.1%±1.0%)。     

超滤分级研究乳清蛋白肽美拉德反应产物的抗氧化活性的影响

以乳清蛋白肽(WPP)为研究对象,利用葡萄糖对其进行美拉德修饰,制备得到美拉德反应产物(Maillard reaction products,MRPs),然后利用超滤技术将MRPs分成相对分子量不同的3个组分(组分I、II和III),测定各组分的抗氧化活性。研究结果表明,组分II(0.8~5 ku)具有最高的还原能力、自由基清除能力和金属离子螯合能力以及最强的抑制脂质氧化能力(P0.05),且随着各组分浓度的增高,其抗氧化活性显著增强(P0.05)。总之,分子量会对MRPs的抗氧化活性产生影响。     

铁棍山药多糖纯化及抗氧化活性

对铁棍山药粗多糖进行纯化分离获得单体组分,并对其抗氧化活性进行评价。利用AB-8大孔树脂对铁棍山药多糖进行富集纯化,再利用DEAE-52纤维素层析柱和Sephadex G-100层析柱分离多糖粗品,利用DPPH自由基清除实验、ABTS自由基清除实验和总还原能力测定评价分离得到的3种铁棍山药多糖组分的抗氧化活性。结果显示,AB-8大孔树脂可纯化铁棍山药粗多糖,使其纯度从53.13%提高到82.57%,获得多糖粗品,洗脱参数为:上样浓度为1.12 g/L,上样体积为4000 mL,上样流速为500 mL/h,洗脱液速度为750 mL/h,洗脱液体积为1000 mL,解吸率可达到95.62%。经过DEAE-52纤维素层析柱和Sephadex G-100层析柱分离得到3种铁棍山药多糖组分DOTP1、DOTP2和DOTP3,得率分别为0.34%、0.42%和0.36%,纯度分别为93.11%、91.22%和92.75%。DPPH自由基清除实验、ABTS自由基清除实验和总还原能力测定结果显示,铁棍山药多糖DOTP1的抗氧化活性优于DOTP2和DOTP3,而3种多糖组分的抗氧化活性都略优于阳性对照VE。研究所用纯化分离方案可实现铁棍山药多糖的分离纯化,得到的3种多糖组分具有较好的抗氧化活性。     

老陈醋类黑精的多酚含量与其抗氧化活性相关性

山西老陈醋熏醅工艺中产生大量的美拉德反应产物类黑精。为了探究老陈醋类黑精的多酚含量与其抗氧化活性的相关性,通过超滤和尺寸排阻色谱法从老陈醋中分离得到不同分子质量的类黑精组分,将老陈醋类黑精经Na Cl解离为类黑精骨架和小分子复合物,分别进行抗氧化活性和组分分析。研究发现:熏醅工艺有利于提高老陈醋的抗氧化活性,主要归功于熏醅过程中生成了大量的类黑精,老陈醋类黑精的抗氧化活性与其组成中的多酚含量正相关。     

不同分子量黑籽瓜种子多肽抗氧化能力的研究

目的:研究不同分子量黑籽瓜种子多肽的抗氧化能力的差异。方法:利用超滤技术对黑籽瓜种子蛋白酶解产物(SWSPs)进行多级分离,得到不同分子量分布的五种组分(SWSPs-L、SWSPs-1、SWSPs-3、SWSPs-5、SWSPs-10),然后以七种抗氧化能力评价体系分别对五种组分进行评价。结果:不同分子量黑籽瓜种子多肽的抗氧化能力不尽相同,分子量在1~3 ku的组分SWSPs-1对超氧阴离子自由基的清除能力最强,而分子量1 ku的组分SWSPs-L则表现出了多重抗氧化机制,该组分与等浓度的EDTA具有相近的螯合效果。结论:黑籽瓜种子多肽的抗氧化能力与其分子量分布和氨基酸组成密切相关,是各方面综合作用的结果。     

小米多肽酶解工艺及其抗氧化和ACE抑制活性

以小米蛋白为原料，制备具有抗氧化活性和血管紧张素转移酶(ACE)抑制活性的食源性多肽。采用碱性蛋白酶、中性蛋白酶和风味蛋白酶酶解小米蛋白，选取最优酶解工艺。选用碱性蛋白酶酶解4 h，得到的蛋白水解液分别通过3 ku和10 ku的超滤膜，得到分子质量＜3，3~10 ku和＞10 ku的3种组分，测定其抗氧化活性和ACE抑制活性。结果表明:采用碱性蛋白酶酶解4 h得到的蛋白水解液经超滤后得到分子质量＜3 ku的多肽具有最高的抗氧化活性和ACE抑制活性，其DPPH清除能力为38.44%，ABTS自由基清除能力为81.62%，羟基自由基清除能力为68.49%，ACE抑制活性为87.53%。此方法得到的多肽分子质量小，功能氨基酸含量较高，具有良好的抗氧化活性和ACE抑制活性。本研究结果为抗氧化肽和ACE抑制肽的开发提供试验依据，对未来工业化的发展提供理论参考。     

不同分子量真鲷鱼骨多肽抗氧化活性的研究

以真鲷鱼骨为原料,经胰蛋白酶、风味蛋白酶酶解后,用截留分子量分别为10、5、3ku的超滤膜将其分离成4个分子量段,研究了不同分子量段对·OH、DPPH·和O2-·的清除能力,对Fe3+还原能力以及对油脂的抗氧化性。结果表明:不同分子量多肽组分均具有抗氧化活性,其抗氧化活性强弱为:分子量小于3ku多肽组分>分子量在3~5ku多肽>分子量在5~10ku多肽>分子量大于10ku多肽。     

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.