超声波法提取小口大枣枣皮红色素及其稳定性研究

以小口大枣枣皮为材料,超声波辅助碱提法提取枣皮红色素,采用单因素实验和正交实验考察了超声功率、料液比、超声时间、NaOH浓度对红色素提取率的影响,在此基础上研究了光照、pH、H2O2、NaSO3对该色素稳定性的影响,并对该色素紫外-可见吸收光谱及红外光谱进行了表征。结果表明:(1)红色素最佳提取工艺参数为超声功率480W,料液比1:15,超声时间25min,NaOH浓度3.5%;(2)该色素在自然光、过氧化氢强氧化剂和碱性环境中稳定性较差;(3)该色素水溶液最大吸收波长293nm;(4)红外光谱分析表明,该色素的主要吸收波数有3422、2924、1715、1577、1141、1081、866、796cm-1等,初步判断该色素为含有苯环及酚羟基的酚类色素。     

桑果红色素的提取及性能

对桑果红色素的提取及稳定性进行了研究，结果表明：桑果红色素的最大吸收波长为480nm，较适宜的提取剂为乙醇，最佳的提取条件为：提取剂体积分数为80％，提取剂pH值为6，提取温度为40℃，提取时间为2h。该色素耐光、耐热、抗氧化、抗还原性强，常用的食品添加剂蔗糖、食用香精、维生素C以及质量浓度小于0．1g／dL的金属离子Mg^2＋、Al^3＋、Ca^2＋、Cu^2＋、Fe^3＋等对色素无明显影响。     

响应面法优化微波辅助提取枣皮红色素

采用响应面法优化微波辅助提取枣皮中红色素的条件。在单因素试验基础上,选择微波时间、微波功率和NaOH浓度为提取因子,进行三因素三水平Box-Behnken中心组合设计,采用响应面法分析优化提取工艺。结果表明:微波辅助提取枣皮中红色素的最优条件为微波功率540W,微波时间134s,NaOH浓度0.51mol/L,料液比1∶10,在此条件下,模型预测值为1.830,验证实验值为1.815,说明模型具有良好的拟合度,能够较好地描述试验结果。     

仙人掌果红色素提取工艺及其稳定性研究

建立了海南野生仙人掌果实中红色素提取的最佳工艺条件,并对提取的红色素的稳定性进行了研究,为利用仙人掌果开发天然色素提供理论依据。红色素的提取工艺条件为：70％的乙醇溶液作为溶剂,提取温度为50℃,提取体系的料液比为1：20,提取pH5．0,提取时间1h。稳定性实验结果表明：仙人掌果红色素在pH3-5时红色素较稳定,色素随着光照的天数、氧化剂、还原剂浓度增加稳定性变差,红色素对金属离子Na^＋、Mg^2＋较稳定,而对Zn^2＋、Sn^2＋、Fe^3＋、Cu^2＋、Pb^2＋较不稳定。     

红枣红色素提取工艺的研究

对红枣红色素提取工艺进行了初步研究,实验结果表明, 红枣红色素提取的最佳工艺条件是0.3mol/L NaOH溶 液为浸提剂,浸提温度75℃,料液比1:30,浸提时间2.5h, 浸提级数二级,在此条件下的提取率可达92.99％。     

红枣红色素提取方法的优化研究

本文对红枣红色素的提取方法进行了研究,通过单因素及正交实验得出红枣红色素的最佳提取工艺条件为:粒度40目、0.2 mol/L NaOH溶液作提取剂、提取时间3 h、提取温度80 ℃、料液比1:20(m/V)、提取级数3级,提取率为95.98%.     

响应面法优化超声波辅助提取枣皮红色素

采用响应面法优化超声波辅助提取枣皮中红色素的条件。在单因素实验基础上,选择超声时间、超声波功率、NaOH浓度和液料比为提取因子,色素提取液吸光度值为响应值,进行四因素三水平Box-Behnken中心组合设计,采用响应面法分析优化提取工艺。超声波辅助提取枣皮中红色素的最优条件为:超声时间30min,超声功率80W,NaOH浓度0.5mol/L,料液比1∶10g/mL(w/v)。在此条件下,模型预测吸光度值为1.445,验证实验吸光度值为1.427,说明模型具有良好的拟合度,能较好的描述实验结果。     

枣皮红色素提取技术的研究

在单因素试验的基础上,利用响应面法优化提取枣皮红色素的工艺条件,根据中心组合设计原理采用三因素三水平响应面分析法,依据回归分析确定最优提取工艺条件:提取剂浓度0.803 9%、提取温度81.2℃、提取时间3.09 h。     

黑豆皮红色素提取及影响其稳定性因素分析

试验研究了黑豆皮红色素的最佳提取条件及光、pH值、温度、氧化剂、还原剂、金属离子、糖类、氨基酸等因素对其稳定性的影响。结果表明，黑豆皮红色素最佳提取工艺是：95％乙醇与0．1％HCl按1：2混合作提取剂，物料与提取剂比为1：40(g：mL)，温度70℃，浸提时间100min。Ca^2 、Cu^2 、Zn^2 对此色素有增色作用；Fe^3 对其有破坏作用；该色素对光、氧化剂、还原剂不稳定；低温下相对稳定；氨基酸对它的破坏作用很大；糖、酸也有不同程度的影响。     

超声波辅助纤维素酶-碱液提取大枣皮红色素工艺的响应面优化研究

本实验研究了纤维素酶解提取大枣皮红色素的最佳工艺.运用响应面分析法筛选出了纤维素酶的最佳酶解条件;通过正交试验设计确定了最佳碱液提取条件.结果表明:当纤维素酶用量为底物的1.26%、酶解温度51.90℃、酶解体系pH值51.9、酶解时间60min、碱液浓度1.0%、提取温度80℃、提取时间35min时,大枣皮红色素的提取率最高,达到1.326μg/g.     

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.