不同挤压温度对糙米体外抗氧化活性的影响

以糙米为原料,采用不同的挤压温度加工糙米,分别提取糙米中的游离态和结合酚,并对提取物中的酚含量、ABTS+自由基清除能力及铁离子还原能力进行了测定,并对各个指标间进行了相关性分析,同时测定了挤压后糙米的淀粉糊化度。结果表明:挤压前后糙米的游离酚和结合酚含量范围分别为210.48~747.70μg/g(GAE/DW)和260.77~470.94μg/g(GAE/DW);游离态提取物的ATBS自由基清除能力和铁离子还原能力的范围分别为1.15~4.52μmol/g(Trolox/DW)和2.57~9.86μmol/g(FeSO4/DW);结合酚的ABTS+自由基清除能力和铁离子还原能力的范围分别为3.09~4.97μmol/g(Trolox/DW)和4.53~7.03μmol/g(FeSO4/DW);糙米的淀粉糊化度随挤压温度的上升而升高,当温度大于130℃后糊化度变化不再显著。相关性分析表明:游离态提取物中的酚含量与抗氧化能力之间不存在显著的相关性,而结合态提取物中的酚含量与抗氧化能力之间具有显著性的相关性。     

基于HepG2细胞模型的褐赭色羊肚菌多酚抗氧化及抗增殖活性研究

本实验研究了褐赭色羊肚菌游离酚和结合酚体内抗氧化能力以及对HepG2细胞的毒性和抗增殖作用。采用HPLC对褐赭色羊肚菌多酚组分进行鉴定,测定多酚抗氧化能力指数(ORAC);以人肝癌细胞HepG2为模型,测定多酚细胞抗氧化活性(CAA值)及抗增殖活性(EC50值)。结果显示:褐赭色羊肚菌游离酚和结合酚含量分别为(4.27±0.07)、(0.14±0.01)mg GAE/g DW;其ORAC值分别为(4624.52±400)、(429.41±60)μmol TE/100 g DW;CAA值分别为(15.33±0.60)、(0.37±0.01)μmol QE/100 g DW(PBS清洗)和(51.84±0.83)、(1.27±0.04)μmol QE/100 g DW(不经PBS清洗)。游离酚和结合酚浓度为125μg/m L和70μg/m L时,对HepG2细胞增殖抑制率分别为77.28%、66.31%,且试验浓度范围内,羊肚菌多酚对HepG2基本无细胞毒性。褐赭色羊肚菌多酚具有一定的细胞抗氧化及抗增殖活性,可将褐赭色羊肚菌作为开发此类功能营养食品的原料,为羊肚菌的进一步综合利用提供理论依据。     

鲜食玉米酚类化合物含量及体外功能活性研究

选择‘天紫23’‘西星黄糯6号’和‘京科糯2000’3个不同颜色的代表性品种，探讨鲜食玉米籽粒在鲜食期和完熟期多酚类化合物及体外功能活性的差异。结果表明，鲜食玉米籽粒中的酚酸类物质大多以结合态形式存在，黄酮和花色苷类物质则主要以游离态形式存在，且鲜食期的多酚含量均高于完熟期。鲜食期多酚提取物的羟基自由基清除率、DPPH自由基清除率和总还原能力均显著(P<0.05)高于完熟期，且多数游离酚表现出高于结合酚的抗氧化活性。3个品种鲜食期游离态和结合态酚类物质的α-淀粉酶抑制率分别是完熟期的1.3～1.5倍和1.4～1.8倍，对α-葡萄糖苷酶的抑制率则分别为1.1～1.5倍和1.5～8.1倍。鲜食玉米多酚提取物对胆酸钠的结合能力最高，游离酚和结合酚分别在172.99～219.92μmol/100 mg DW和362.48～417.16μmol/100 mg DW,3个品种鲜食期的胆酸盐结合能力均高于完熟期，结合态多酚表现了更强的胆酸盐结合能力。     

苦荞麸皮多酚抑制人结肠癌细胞Caco-2增殖活性研究

研究了产自重庆酉阳的苦荞(Fagopyrum tartaricum L.Gaerth,FG1)麸皮和四川西昌的苦荞(Fagopyyrum tartaricum L.Gaerth,FG2)麸皮中酚类化合物的含量、抗氧化和抗增殖活性。结果表明:FG1和FG2 2种苦荞麸皮总酚含量分别为(26.40±0.41)和(27.00±0.72)mg GAE/g DW,且游离态是其酚类化合物的主要存在形式(约占其总酚含量的93%);2种苦荞麸皮酚提取物均表现出一定的抗氧化性,并且FG2的抗氧化能力强于FG1(P0.05),FG1和FG2的DPPH自由基清除能力总IC50值分别为(39.56±2.76)和(24.69±0.33)μg·mL~(-1);还原力总EC_(50)值分别为(97.92±1.4)和(73.18±4.32)μg·mL~(-1);在抗增殖试验中,与对照组相比,FG1和FG2游离酚提取物均能明显抑制人结肠癌细胞Caco-2增殖(P0.05)。然而,在不产生细胞毒性的浓度范围内,其结合酚提取物却表现出极弱的抗增殖作用。     

不同品种龙眼果肉酚类物质的抗氧化活性比较

为研究不同龙眼品种资源中酚类物质、黄酮类化合物含量及其抗氧化性差异,选取广东省农业科学院果树研究所龙眼资源圃的24个龙眼品种,分析其果肉中游离态和结合态总酚、总黄酮物质的含量,采用DPPH自由基清除能力、ABTS总抗氧化能力、FRAP抗氧化能力和氧自由基吸收能力ORAC四种不同方法评价其体外抗氧化能力差异;不同龙眼品种果肉总酚、总黄酮含量与DPPH、ABTS、FRAP、ORAC四种不同方法测定的抗氧化能力的变幅和变异系数较大,呈现出显著的基因型差异;不同品种龙眼果肉的多酚和黄酮的含量分别与ABTS自由基清除能力、FRAP和ORAC呈极显著(p0.01)正相关关系,而与DPPH自由基清除能力的EC50值呈极显著负相关关系(p0.01)。采用快速聚类法将24个不同品种的龙眼聚成多酚及总黄酮含量和抗氧化能力差异显著的三大群类。不同品种龙眼果肉游离态和结合态酚类物质含量与其抗氧化活性均呈显著正相关关系,提示酚类物质是龙眼果肉抗氧化活性的主要成分;酚类物质和黄酮类物质在龙眼果肉中主要以游离态存在,其中结合态平均占总酚含量的17.45%。     

玫瑰蜂花粉中不同存在形态酚类物质的组成及其抑制B16黑色素瘤细胞的活性

本文研究了玫瑰蜂花粉中游离态和结合态酚酸类物质含量和组成;采用铁离子还原能力、ABTS和DPPH自由基清除能力三种模型评价其抗氧化能力;同时测定了其对蘑菇酪氨酸酶活性的抑制作用;并进一步研究了对B16细胞的增殖形态、黑色素含量和酪氨酸酶活性的影响。结果表明,蜂花粉中游离态和结合态的总酚含量分别为23.36和1.47 mg GAE/g干重(DW),总黄酮含量为19.12和2.42 mg RE/g DW。酚酸类物质大多以游离态形式存在,富含槲皮素和芦丁,而结合态中鞣花酸和3,4-二甲氧基苯甲酸含量较高;游离态和结合态多酚在三种模型中均显示较好的抗氧化活性;抑制蘑菇酪氨酸酶活性IC50分别为22.26和26.34μg/m L,显著高于Vc;一定程度上影响了B16细胞的增殖和形态,同时显著降低细胞内相对黑色素含量和酪氨酸酶活性。玫瑰蜂花粉中不同形态多酚的活性与其酚酸的含量和组成有直接的关系。     

大花罗布麻不同部位酚类物质含量及其抗氧化活性比较研究

目的：比较大花罗布麻根、茎、叶、花4 个部位中游离态和结合态酚类物质的含量和抗氧化活性的差异,并分析含量与抗氧化活性之间的相关性。方法：采用Folin-Ciocalteu法、NaNO2-Al(NO3)3法分析罗布麻的根、茎、叶、花4 个部位的游离态和结合态总多酚、总黄酮含量,采用DPPH自由基清除能力、ABTS+·清除能力和铁离子还原能力3 种方法评价其体外抗氧化能力差异。结果：大花罗布麻总酚含量次序为：叶＞根＞花＞茎,各样品间存在显著性差异（P＜0.05）。各部位游离酚、结合酚和总多酚含量分别介于3 560.19～6 273.23、13.45～22.01和3 582.2～6 286.68 mg GAE/100 g干质量,其游离态多酚占总酚含量百分比平均为99.60%;游离态黄酮、结合态黄酮和总黄酮含量分别介于1 080.30～2 488.21、9.69～28.59、1 106.81～2 516.80 mg RE/100 g 干质量,其游离态黄酮占总黄酮含量的百分比平均为98.64%。大花罗布麻叶提取物清除DPPH 自由基、ABTS+·能力和总还原力最强,抗氧化活性与总酚含量之间具有良好的线性关系（r＞0.950 0）。结论：大花罗布麻各部位中含有较丰富的酚类物质,具有较强的抗氧化活性。     

石榴皮游离与结合态多酚的组成和抗氧化性研究

目的:研究石榴皮游离与结合态多酚含量、组成和抗氧化性的异同,为其提取和利用提供依据。方法:将3个石榴品种的成熟果实分别制成4类皮粉,采用超声提取法和碱液溶出法制取各皮粉的游离态和结合态多酚,采用3种方法测定其酚类组成和含量,采用4种方法评价其抗氧化能力。结果:4类皮粉的游离态多酚、类黄酮和单宁含量分别为107.55~157.60mg GAE/g DW、24.24~44.54mgQUE/gDW和143.03~231.44mgTAE/gDW,结合态多酚、类黄酮和单宁含量分别为7.35~30.89mgGAE/g DW、2.25~11.56mgQUE/gDW和9.01~18.86mgTAE/g DW。全皮、外层皮、内层皮和皮渣粉的多酚含量差异显著(p0.05),其中皮渣游离态多酚含量最低而结合态多酚含量最高,各品种的同类皮粉的多酚含量有显著差别(p0.05)。同一皮粉的游离态和结合态多酚的抗氧化能力彼此相近,其大小与多酚和单宁含量均显著相关(p0.01)。结论:提取石榴皮多酚的材料可根据原料的实际状况而选全皮、内层皮或皮渣,提取游离酚可获取材料中大部分多酚。结合态多酚的抗氧化能力与游离态多酚相似但含量低。     

干燥方式对柠檬片中游离态、结合态多酚及抗氧化特性的影响

采用冷冻干燥(FD)、热风干燥(AD)、红外干燥(IRD)及真空干燥(VD)对柠檬片进行干制,利用分光光度法测定游离态、结合态多酚含量及抗氧化能力(清除ABTS·+能力、铁离子还原能力和清除DPPH·能力),并采用超高效液相色谱对酚类物质进行定性和定量分析。结果表明,4种干制柠檬片结合态多酚含量、清除ABTS·+能力、铁还原能力均分别高于游离态多酚的相应含量及能力,而其游离态多酚清除DPPH·能力均低于结合态多酚。4种干制柠檬中主要酚类物质为类黄酮,其含量显著高于酚酸含量;柠檬中游离态多酚主要为橙皮苷、圣草枸橼苷和芦丁,三者含量占游离态多酚总量的91.18%～94.92%;结合态多酚主要为原儿茶酸、柚皮苷和橙皮苷,三者含量占结合态多酚总量的81.83%～83.64%。热处理对柠檬中酚类物质呈现不同影响。与FD处理相比,热处理导致柠檬中总酚、总酚酸与结合态多酚含量下降,游离态酚酸总量、生物利用多酚含量及其生物利用度上升;而结合态类黄酮总量上升,游离态类黄酮总量下降。其中3种热处理干燥方式中,AD处理组酚酸与类黄酮总量均为最高,分别为325.77 mg/100 g DW和2 317.57 mg/100 g DW。     

不同品种番薯抗氧化活性的对比及热加工稳定性

为比较几种典型番薯品种的多酚含量及抗氧化活性,以冷冻丙酮和Na OH-乙酸乙酯分别提取番薯皮及番薯肉中游离态酚和结合态酚,并采用Folin-Ciocalteu比色法,亚硝酸钠-硝酸铝-氢氧化钠比色法分别测定提取物中多酚和黄酮的含量,以氧自由基吸收能力(ORAC)指征其抗氧化活性。发现番薯皮中总多酚、总黄酮含量及ORAC值均高于相应品种的番薯肉;而在不同品种中,以紫皮紫心番薯中皮、肉中总酚含量最高,分别为(336.87±2.83)×10~(-2)和(121.79±1.68)×10~(-2)mg GAE/g;紫皮紫心番薯皮ORAC值为(6917.79±672.70)×10~(-2)μmol TE/g,高于其他品种,但不同品种薯肉ORAC值无显著性差异。探究了不同加热条件对紫皮紫心薯肉中多酚、黄酮和ORAC值的影响,与未经加热的生薯肉相比,100℃下加热30 min能使其提取物中多酚、黄酮和ORAC值分别提高2倍、2.6倍及5.7倍,表明热加工有利于提高番薯中多酚类物质的释放,提高其抗氧化活性。     

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.