生物自显影技术在荸荠英抑菌成分分离中的应用

应用硅胶板层析技术,以枯草芽孢杆菌作为指示菌,研究生物自显影对荸荠英提取物抑菌成分的活性跟踪方法。用200 mg/mL荸荠英提取物丙酮溶液点样4μL,以二元溶剂V(CCl_4):V(甲醇)=8.5:1.5展开,贴板10min,37℃培养10h即可得到清晰的抑菌斑色谱图。应用该方法可将荸荠英粗提物乙酸乙酯部分分离得到6个活性组分。     

荸荠英提取物抑菌成分稳定性的探讨

本文主要对荸荠英抑菌性能进行研究，结果表明，荸荠英粗品提取物具有强抑菌活性，在中性pH条件下提取物对细菌具有较好的抑菌效果，明显强于山梨酸钾。同时以金色葡萄球菌和大肠杆菌为指示菌，研究荸荠英粗品提取物活性成份的稳定性，结果表明提取物经过酸、碱处理后均具有一定的抑菌活性，碱处理对其抑菌活性有部分减弱；温度对其抑菌活性影响不大，在121℃下处理30min，抑菌活性才略有减弱；紫外照射及常见金属离子(Na^ 、K^ 、Ca^2 、Fe^2 、Fe^3 )对其稳定性几乎没有影响。     

荸荠英提取物抑菌活性及其应用研究

为了提高荸荠的深加工附加值,本实验从荸荠加工废弃物荸荠皮中提取抑菌物质,研究其抑菌活性及其应用。结果表明,荸荠英提取物对大肠杆菌、金黄色葡萄球菌、藤黄微球菌、枯草芽孢杆菌均有抑制作用,其中对金黄色葡萄球菌的抑制作用最强,且持续性好。荸荠英提取物对大肠杆菌、金黄色葡萄球菌、藤黄微球菌的抑制作用高于1%的山梨酸钾溶液,而对枯草芽孢杆菌的抑制作用与其比较接近;利用荸荠英提取物能有效防止彩色水果番茄贮藏过程中由根霉和链格孢引起的腐烂,与根霉相比,荸荠英提取物对链格孢的抑制效果更好。     

荸荠皮抑菌活性成分的研究

目的 鉴定荸荠皮中抑菌活性成分的种类及结构.方法 先将荸荠皮粗提物用不同极性的有机溶剂分步提取,通过抑菌实验筛选抑菌活性最强的提取物,通过硅胶柱色谱分离纯化,得到抑菌活性最强的两个部分,气相色谱-质谱（GC-MS）鉴定抑菌物质的种类及结构.结果 荸荠皮抑菌物质中含有甾醇类、有机酸类、酯类和黄酮类4类活性成分共11种活性物质.结论 此鉴定结果符合荸荠皮提取物的抑菌特性,为荸荠皮抑菌物质的研究提供了依据.     

二组分生姜复合抗氧化剂抑制大肠杆菌作用初探

以生姜提取物为主要原料,茶叶和荸荠皮提取物、柠檬酸、抗坏血酸等原料组合为生姜复合抗氧化剂,研究对大肠杆菌的抑菌作用,测定抑菌作用最强组成和配比的复合物,其抑菌活性与热稳定性、总黄酮含量的关系。结果表明,生姜提取物中含有黄酮类化合物;当总浓度相同时,二组分复合物比单组分生姜提取物的抑菌效果更好,而二组分复合物中抑菌活性最强的组成为：生姜提取物＋柠檬酸;最佳质量配比为：生姜提取物：柠檬酸为11：9;该复合物中总黄酮含量与抑菌效果无明显关系;经热处理后的生姜复合抗氧化剂的抑菌活性没有明显变化。     

荸荠皮抑菌活性成分微波提取工艺及抑菌特性

为了研究荸荠皮抑菌活性成分,利用微波辅助提取技术提取荸荠皮中的抑菌活性成分,以抑菌效果为评价指标,研究了微波功率、微波时间、乙醇体积分数和液固比等因素对抑菌效果的影响。提取物用石油醚萃取,研究了石油醚萃取相对枯草芽孢杆菌和酿酒酵母的最低抑菌浓度,并考察了温度、p H和紫外线等对石油醚萃取物抑菌活性的影响。通过正交试验确定的荸荠皮抑菌活性成分最佳提取工艺为:微波功率250 W、微波时间4 min、乙醇体积分数50%、液固比25∶1 mL/g。石油醚相对枯草芽孢杆菌的最低抑菌浓度为0.062 5 mg·mL~(-1),对啤酒酵母的最低抑菌浓度为0.25 mg·mL~(-1);石油醚相抑菌活性成分在一定范围的温度、pH和紫外线照射时间等条件下依然能保持较好的抑菌活性。     

荸荠皮抑菌物质稳定性及抑菌特性研究

目的研究荸荠皮提取物的稳定性及多菌种抑制作用。方法首先,采用热水浸提法得到荸荠皮提取物,将其在不同温度、pH值、不同紫外线照射时间、不同糖、盐溶液中放置,测定其抑菌效果。其次,用滤纸片法测定荸荠皮提取物对多种菌类的抑制作用。结果荸荠皮提取物在温度和紫外光的处理后稳定性保持不变;提取物在不同浓度的盐溶液、糖溶液和pH环境中其稳定性有一定的变化。提取物对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌和巨大芽孢杆菌的抑制作用较好。结论本文的研究结果符合荸荠皮提取物的特性,对今后深入研究荸荠皮提取物有重要的意义。     

超声波提取荸荠皮抑菌物质的工艺研究

目的：对超声波法提取荸荠皮中抑菌物质的工艺进行研究，讨论各单因素对抑菌效果的影响；方法：经正交试验得到的工艺参数为：物料粒度60目、乙醇浓度65％、料液比1：10、超声波提取时间50min、提取次数1次，此条件下对大肠杆菌和金黄色葡萄球菌的抑茵圈直径分别为13．3mm和14．3mm。     

生姜和荸荠皮提取物抗菌作用研究

本文研究了生姜,荸荠 皮提取物混合液的抗菌作用。结果表明;生姜和荸荠皮提取物以５：５混合,在一定浓度下,对细菌、啤酒,酵母,黑曲霉具有良好抑菌作用。同时它们具有抑菌ｐＨ范围广,热稳定性强特点,对食品有一定的防腐作用。     

浙江地区不同经济品种杨梅叶提取物的抑菌活性研究

为开发替代抗生素使用的植物源饲料添加剂,本实验对浙江地区不同经济品种的杨梅叶提取物进行了抑菌活性的研究.采用水提和醇提法对东魁、荸荠、丁岙和晚稻等九种经济品种杨梅叶进行了提取和真空浓缩.分别测定了提取物得率和抑菌效果,结果表明,九种杨梅叶提取物均具有抑菌活性,晚稻品种水提液抑菌效果显著高于其他品种,醇提液抑菌效果的水晶种、深红种差异不大,高于其他品种.     

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.