脂肪酶催化阿魏酸甘油酯的合成

阿魏酸甘油酯是一种具有较高水溶性的阿魏酸衍生物,具有广泛的生理活性,可应用于食品中。试验探究在固定化脂肪酶的催化下,阿魏酸与甘油合成阿魏酸甘油酯的工艺,并探索其合成的最佳反应条件:温度60℃,转速70 r/min,酶用量10%(以质量计),时间10 h,展开剂选用三氯甲烷-苯-甲醇-乙酸,展开剂比例为32︰20︰1.5︰1,在此条件下阿魏酸的转化率最高,为85.30%。同时对阿魏酸及阿魏酸甘油酯清除DPPH自由基的功能特性进行研究,结果表明,阿魏酸甘油酯对DPPH自由基有一定清除作用,且清除能力强于阿魏酸。     

超声波辅助酶法提取玉米皮阿魏酸的工艺优化及抗氧化研究

采用响应面法优化超声波辅助木聚糖酶联合提取玉米皮中阿魏酸工艺,建立阿魏酸得率与超声温度、超声时间、酶添加量、酶解时间四因素的数学模型,确定玉米皮阿魏酸的最适提取工艺参数;以清除自由基能力评价玉米皮阿魏酸的抗氧化活性。结果表明:玉米皮阿魏酸提取的最佳工艺条件为超声温度33℃、超声时间80 min、酶添加量0.83%、酶解时间65 min、酶解温度50℃,阿魏酸得率为3.47 mg/g。在此优化条件下,玉米皮阿魏酸对DPPH自由基、羟自由基及超氧阴离子自由基均具有较强清除作用,半数抑制浓度分别为0.552、0.282和0.111 mg/m L。     

野生蓝莓酚酸成分鉴定及其清除细胞内自由基活性研究

酚酸具有良好的自由基清除活性,能有效降低非酒精性脂肪肝、心血管疾病、糖尿病等疾病发生风险。酚酸是大兴安岭野生蓝莓的主要酚类物质之一,其成分尚不清楚。本文采用柱层析法纯化蓝莓中的酚酸组分,用高效液相色谱法进行成分鉴定与含量检测。以AAPH诱导Hep G-2细胞氧化损伤模型评价酚酸清除细胞内自由基活性。从物质结构特性出发,通过循环伏安法分析酚酸的氧化-还原能力,探讨酚酸清除细胞内自由基活性机理。结果表明:蓝莓酚酸主要由咖啡酸、绿原酸、肉桂酸、阿魏酸、没食子酸、对香豆酸和原儿茶酸7种酚酸组成,含量较多的为绿原酸(21.2%)、阿魏酸(8.3%)、对香豆酸(7.0%)和咖啡酸(4.6%)。4种主要酚酸对细胞内自由基清除能力为咖啡酸绿原酸阿魏酸对香豆酸,其失电子能力依次为绿原酸咖啡酸阿魏酸对香豆酸。酚酸是蓝莓的主要抗氧化成分之一,其失电子能力是影响酚酸清除细胞内自由基活性的主要原因。     

四种酚类化合物体外抗氧化活性的比较研究

以L-抗坏血酸棕榈酸酯为对照,采用DPPH自由基清除能力、ABTS自由基清除能力、铁离子还原能力和还原力法,综合评价咖啡酸、芦丁、阿魏酸、槲皮素的抗氧化活性。结果表明:在清除DPPH自由基能力上,咖啡酸和槲皮素的作用均强于阿魏酸、芦丁和L-抗坏血酸棕榈酸酯;在清除ABTS自由基方面,咖啡酸和槲皮素的作用最强,芦丁最弱;在铁离子还原能力和还原力方面,咖啡酸和槲皮素具有很强的还原能力,阿魏酸具有较强的还原能力。酚类化合物的抗氧化活性主要取决于它们含有的酚羟基数目以及化学结构中的位置。     

玉米芯功能性低聚糖分级纯化及抗氧化活性研究

探究玉米芯功能性低聚糖分级纯化前后不同组分的组成、理化性质和抗氧化活性。以玉米芯为原料,采用活性炭柱层析法对玉米芯功能性低聚糖进行分级纯化,对纯化前后组分的聚合度、相对分子质量、阿魏酸基团以及红外光谱特性进行分析,并对酶解低聚糖粗提物(EH)及其纯化组分的自由基清除能力和抑制脂质过氧化能力进行比较分析。结果表明：活性炭水洗脱低聚糖组分(WO)、醇洗脱低聚糖组分(EO)均主要由木糖和阿拉伯糖组成,其中WO含有结合态阿魏酸,为阿魏酰阿拉伯低聚木糖;EO不含结合态阿魏酸,为阿拉伯低聚木糖。EH及其纯化组分WO、EO均具有一定的清除自由基(DPPH·、·OH、ABTS⁺·)能力和抑制脂质过氧化能力,且随浓度的增加而增加,WO抗氧化活性最强,EH次之,EO抗氧化活性较弱。     

阿魏酸的功能性研究进展

阿魏酸是一种天然活性物质,既是抗氧化剂又是抗炎症因子,能够直接清除自由基。目前对阿魏酸的功能性研究和应用日趋广泛。对阿魏酸的功能性研究进行综述,介绍近年来阿魏酸在治疗冠心病、心血管疾病、对阿尔兹海默症及记忆力缺陷的治疗、抑制疼痛、对肺部疾病、肝脏疾病、糖尿病和改善肾功能及抗辐射治疗等方面的研究现状和成果。     

青麦仁麸皮中阿魏酸的抗氧化性和抑菌活性研究

通过铁离子还原法、DPPH自由基清除法、羟基自由基清除法、ABTS自由基清除法来探索阿魏酸的体外抗氧化活性;采用试探性试验与牛津杯法、琼脂培养基稀释法和液体培养法分别测定青麦麸阿魏酸对部分食品腐败菌的敏感性、最小抑菌浓度和最小杀菌浓度.试验结果表明,随着阿魏酸的质量浓度升高,其铁离子还原能力逐渐增大;随着摩尔浓度升高,其对DPPH自由基、羟基自由基和ABTS自由基清除能力逐渐增大.同时,阿魏酸对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌有抑制效果,随着阿魏酸浓度的提升,其相对应的抑制作用逐渐增强,最低抑菌浓度分别为12.5 mg/mL、6.25 mg/mL、6.25 mg/mL,最低杀菌浓度分别为200 mg/mL、>400 mg/mL、200 mg/mL.     

扇贝边活性肽的分离及其对羟自由基的清除活性研究

目的:确定扇贝边酶解产物中对羟自由基(·OH)具有清除作用的活性肽的分布及活性肽分子量的大小。方法:采用葡聚糖凝胶G-25和G-200分别对扇贝边酶解产物进行分离,用标准分子量作为参照,检测各分离组分对羟自由基的清除率及活性肽分子量的大小。结果表明:枯草杆菌蛋白酶酶解扇贝边的酶解产物中,有两个分离组分具有羟自由基清除活性,其对应的活性肽分子量为8000Da和1800Da,这两种活性肽对羟自由基的清除率分别为73.6%和64.3%;木瓜蛋白酶酶解扇贝边的酶解产物中,也有两个分离组分具有羟自由基清除活性,其对应的活性肽分子量为9000Da和1400Da,这两种活性肽对羟自由基的清除率分别为72.7%和66.1%。结论:用枯草杆菌蛋白酶和木瓜蛋白酶酶解扇贝边所得的酶解产物中分别含有两种对羟自由基具有清除作用的活性肽。     

纤维素酶水解处理提高燕麦全粉中总多酚含量与抗氧化活性

采用Folin-酚法和高效液相色谱法考察了纤维素酶水解处理对燕麦粉中总多酚及多酚组分含量的影响,并利用2,2’-联氮双-（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt,ABTS）自由基、1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基清除能力、铁离子还原能力（ferric reducing antioxidant power,FRAP）和蛋白损伤修复等方法测定酶解前后提取液的体外抗氧化活性。结果表明：酶解处理以后可显著增加燕麦粉中总多酚含量,尤其是阿魏酸含量提高了11～24 倍;酶解处理后燕麦粉多酚提取物的ABTS＋·、DPPH自由基清除能力和FRAP值等体外抗氧化活性和蛋白氧化损伤修复能力得到显著增强。总体而言,纤维素酶水解处理能够有效提高燕麦粉中总多酚含量及其功能活性,主要原因可能是阿魏酸等酚酸物质含量的提高。     

不同谷物蛋白肽对自由基清除作用的研究

采用碱性蛋白酶对3种谷物蛋白(小麦、大米、玉米)进行水解得到谷物蛋白水解物,利用超滤对水解液进行分离,对比研究了所得不同谷物蛋白肽对自由基清除作用的效果,包括氧自由基、DPPH自由基和还原力等。结果表明,谷物蛋白种类及肽的相对分子质量大小对自由基清除作用均有较大影响,大米和玉米蛋白水解物的自由基清除能力较好;经超滤膜分离后,3种谷物蛋白肽中小于1 ku组分的自由基清除作用均高于其他组分。     

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.