不同提取方法对海蒿子多糖性质的影响研究

海蒿子多糖是存在于海洋褐藻植物海蒿子细胞内和细胞间的一种天然大分子物质,具有多种生物活性。本研究比较了传统水提法、柠檬酸提取法、超声法、超声波辅助水提法、超声波辅助柠檬酸提取法五种方法提取海蒿子多糖的性质区别。结果表明采用柠檬酸法提取海蒿子多糖得率最高,可达5.31%,是传统水提法的1.8倍。并且,不同方法提取的海蒿子多糖分子量大小存在差异性,其中传统水提法提取多糖的分子量为739.663ku,约是超声法提取多糖分子量大小的19倍。通过不同抗氧化能力评价指标的测定表明传统水提法提取多糖的DPPH·清除能力在浓度0.5mg/m L时为54.77%,ABTS+清除能力在浓度0.25mg/m L时为74.59%,还原力在浓度0.3mg/m L时为1.381,氧自由基吸收能力(ORAC)值可达5404.90μmol Trolox/g。且硫酸基含量最高,为12.28%,具有较好的抗氧化活性。因此,采用传统水提法工艺来提取多糖更利于维持海蒿子多糖的功能活性,便于进一步的深入研究。     

不同提取方法对蛹虫草基质多糖的特性研究

以废弃的蛹虫草培养基基质为原料,利用水提法、酶解法、超声波法、超声波-酶法、微波法和微波-酶法来提取蛹虫草基质多糖,研究不同提取方法下蛹虫草基质多糖得率、多糖黏度及多糖抗氧化活性的区别来比较六种提取工艺的优缺点。结果表明:超声波-酶法所得蛹虫草基质多糖的得率最高,达30.27%,水提法最差,为10.69%。不同提取方法所得的多糖溶液黏度均随多糖溶液浓度的增大而增大,在相同浓度下多糖溶液的表观黏度大小依次为水提法微波法酶法微波-酶法超声波法超声波-酶法。超声波-酶法提取的蛹虫草基质多糖体外抗氧化活性最好,而水提法的多糖抗氧化活性最差。     

不同提取方法对山药多糖含量及其体外抗氧化活性的影响

采用水提法、超声法、微波法和酶法分别提取制备山药多糖,苯酚硫酸法测定多糖含量,采用还原力、DPPH·清除能力、·OH清除能力、O-2·清除能力为体外抗氧化能力的评价指标,比较不同提取方法对多糖含量和抗氧化活性的影响。结果表明:相对于其他3种提取方法,酶法提取得率最高,可达9.65%,且耗时短,为120 min。就其还原力、DPPH·清除能力、·OH清除能力而言,酶法制备的多糖抗氧化能力最好,其余依次为微波法、水提法、超声法。而就其O-2·自由基清除能力而言,微波法酶法水提法超声法。因此,采用酶法提取工艺来制备山药多糖既有利于提高产量、维持多糖的功能活性,还缩短了提取时间,且安全、环保,便于进一步研究其抗氧化能力。     

响应面优化酶法提取虎斑乌贼肌肉多糖的工艺及抗氧化活性测定

研究胰蛋白酶提取虎斑乌贼肌肉多糖的工艺及体外抗氧化活性,并与水提法和碱提法的多糖进行比较。在单因素试验基础上以响应面法优化酶法提取多糖的工艺,结果显示最佳工艺条件为:酶解温度55℃、料液比1∶40(g/mL)、酶解时间4 h、加酶量2.5%,此时虎斑乌贼肌肉多糖得率为4.15%,优于水提法和碱提法的多糖得率。体外抗氧化活性研究表明酶法提取的多糖比碱提和水提的多糖具有更好的抗氧化活性,当多糖质量浓度为4 mg/mL时,水提、碱提和酶提虎斑乌贼肌肉多糖对·OH的清除率分别为50.15%、55.14%和89.47%,其IC50值分别为4.51、3.56 mg/mL和0.82 mg/mL;对DPPH自由基的清除率分别为28.89%、31.48%和40.80%,其IC50值分别为16.66、15.43 mg/mL和11.50 mg/mL;对O2-·的清除率分别为75.43%、81.63%和97.00%,其IC50值分别为1.15、0.69 mg/mL和0.29 mg/mL;还原力大小分别为0.134、0.156和0.193。综合分析表明,酶提法得到的多糖得率较高且具有较好的体外抗氧化活性。     

五味子多糖不同提取工艺的研究

以北五味子为原料,多糖得率为指标,研究水提法、酶法、超声波辅助法三种方法提取北五味子多糖,通过正交实验的方法分别研究了多糖的最佳提取工艺条件.结果表明:超声波辅助法提取五味子多糖得率大于酶法和水提法,其最佳工艺条件为:料液比1∶25,超声时间40min,超声功率600W,提取温度55℃,多糖得率为4.67％.     

广金钱草多糖的超声波提取及其对亚硝酸盐的清除作用研究

采用超声法提取广金钱草多糖,以多糖得率为指标,通过单因素试验和正交试验优化广金钱草多糖提取工艺,并测定了广金钱草多糖体对亚硝酸盐的清除作用。实验结果表明,超声波提取广金钱草多糖的最佳工艺为:超声功率150W,料液比1:40,提取时间60min,提取次数3次;广金钱草多糖对亚硝酸盐具有较好的清除作用,清除率与多糖的浓度和反应时间呈正相关性,当多糖浓度为10mg/mL时,反应时间50min,清除率可达90%以上。     

总评归一值法优选山豆根茎多糖的微波预处理-超声波提取工艺及生物活性研究

目的:研究山豆根茎多糖的微波预处理-超声波提取工艺及其生物活性。方法:以多糖得率和多糖纯度的总评归一值为评价指标,采用正交设计优选山豆根茎多糖的微波预处理-超声波提取工艺,并对其稳定性、抗氧化活性和清除亚硝酸盐活性三种生物活性进行研究。结果:最佳提取工艺条件为:解析剂比1∶5(g/m L),微波时间30 s,料液比1∶25(g/m L),超声功率140 W,提取时间20 min,该工艺条件下,多糖得率为3.27%,多糖纯度为29.49%,提取效果优于热水浸提法和超声波提取法。多糖稳定性研究表明粗多糖在温度40~70℃、Ca~(2+)或柠檬酸中较稳定,但在温度高于70℃、H_2O_2、Na_2SO_3、VC、Na~+、Al~(3+)、Cu~(2+)或Fe~(3+)的条件下稳定性较差。体外抗氧化活性研究表明粗多糖具有一定的抗氧化活性,当浓度为1.96 mg/m L时,微波预处理-超声波提取法粗多糖对·OH和O-2·的清除率分别可达78.14%和71.16%;亚硝酸盐清除研究表明粗多糖具有良好的清除亚硝酸盐活性,当添加量为20 m L(或19.60 mg)时,清除率可达82.94%,清除效果与0.32 mg VC相当;相同浓度下,微波预处理-超声波提取法所提取的粗多糖对O-2·和亚硝酸盐的清除活性与超声提取法相当,且对·OH的清除活性优于超声提取法。结论:山豆根茎中富含多糖类物质,具有良好的抗氧化活性和清除亚硝酸盐活性,粗多糖稳定性较差,建议低温避光保存。     

罗平小黄姜多糖提取工艺的优化及抗氧化活性测定

采用水提醇沉法提取罗平小黄姜中的多糖,正交试验显示最佳提取工艺为料液比1∶20、提取温度90℃、提取时间160min,在此条件下罗平小黄姜多糖的得率达到6.16%。此外,当多糖浓度达到1.0mg/mL时,对DPPH·和·OH的清除率分别可达57.1%和44.5%,清除DPPH·的IC_(50)为0.96mg/mL。     

生姜多糖类物质的提取及抗氧化活性研究

目的以生姜为原料,采用超声波辅助法和热水浸提法提取生姜多糖类物质并进行抗氧化活性对比研究。方法经单因素试验结合响应面优化设计考察最优提取工艺参数,同时对2种方法提取的生姜多糖抗氧化活性进行对比分析。结果超声波辅助法提取生姜多糖最佳提取条件为:超声温度48℃,超声功率340W,超声时间21 min,液固比50:1(m L/g),在此条件下多糖得率为6.87%;热水浸提法的最佳提取条件为:温度72℃,时间164 min,液固比40:1(m L/g),在此条件下多糖得率为3.13%。抗氧化活性测定结果表明,超声波辅助法和热水浸提法提取生姜多糖的DPPH自由基清除能力的IC_(50)值分别为0.21 mg/m L和0.42 mg/m L,还原能力分别相当于维生素C的3.14%和0.5%,铁离子螯合能力的IC_(50)值分别为2.17 mg/m L和4.18 mg/m L,超声波辅助法提取的生姜多糖的DPPH自由基清除能力、还原力和金属螯合能力分别是热水浸提法提取的生姜多糖的2倍、6倍和1.9倍。结论生姜多糖具有一定的抗氧化活性,本研究可为生姜多糖的提取提供参考。     

不同提取方法对槐米多糖抗氧化活性的影响

利用超声辅助提取法和热水浸提法分别提取槐米多糖,苯酚硫酸法测定多糖含量,采用还原能力、超氧阴离子自由基(O-2·)的清除能力、DPPH有机自由基的清除能力、羟自由基(·OH)的清除能力作为体外抗氧化作用评价的四个指标,并与VC、BHT进行比较。结果表明:超声波提取多糖得率比热水浸提法提高了21.6%;在0.125~2.0mg/m L浓度范围内,对自由基清除作用:VC>超声提取多糖>水提多糖>BHT。其中,超声提取多糖对O-2·(清除率,70.78%)和·OH(清除率,75.34%)的清除力略高于水提多糖(清除率分别为62.28%和70.45%),低于VC的清除力(清除率分别为98.21%和94.53%)。由此可见,槐米粗多糖有一定的抗氧化活性,而且不同提取方法得到的槐米多糖的抗氧化活性不同。     

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.