紫胶红色素稳定性研究

研究紫胶红色素在不同环境下的稳定性,结果表明：紫胶红色素具有较好的光、热稳定性,室外阳光下28d 保存率高于95%;在4℃低温至100℃高温范围内均有较好的稳定性,8h 保存率均超过93%;紫胶红色素的抗氧化性较高,而在一定的还原剂条件下保存率略有降低;常用食品添加剂对紫胶红色素有增色及护色作用;Fe3+、Fe2+、Ca2+、Sn2+ 离子可破坏色素水溶液稳定性,而其他金属离子对稳定性影响不明显;紫胶红色素在酸性环境下保存率较高,当pH 值增大至碱性范围会使其显著失稳。     

食用天然红色素胭脂虫红的性质研究

为保证胭脂虫红色素的品质,该文重点研究了pH值、日照、温度、储藏、部分金属离子和部分食品添加剂等对胭脂虫红色素稳定性的影响。结果表明：该色素适宜在弱酸性至中性环境中使用;其光稳定性较差,日照24h后色素保留率仅为18．4％;热稳定性和贮藏稳定性良好;对氧化性金属离子较敏感;常用食品添加剂对其稳定性影响微弱。     

真丝绸胭脂虫红色素无媒染色

为使胭脂虫色素在无媒染时较好地上染真丝绸,采用聚乙烯亚胺来改性真丝织物。利用紫外光谱对所用色素进行定性分析,主要研究了胭脂虫红色素对改性真丝织物的工艺条件。结果表明,改性剂聚乙烯亚胺能提升胭脂虫红色素对真丝绸的染色性能。改性的最佳工艺为:改性剂质量浓度0.8 g/L,pH=8,改性温度60℃,改性时间50 min。胭脂虫红色素染色改性真丝织物的最优工艺为:胭脂虫红色素的质量分数为3%,染液的pH为7,染色温度为80℃,染色时间为60 min,染色浴比为1∶30。改性染色织物的K/S值不低于媒染染色,且耐皂洗色牢度比媒染染色提高1级。     

蛋白酶胭脂虫天然染料的提取及羊毛织物染色性能研究

利用蛋白酶对胭脂虫干体内的胭脂红酸进行萃取,通过天然染料胭脂虫色素对羊毛织物进行染色.利用蛋白酶进行色素提取,具有温度低、萃取时间短、提取效果好等特点.实验确定提取工艺为:蛋白酶浓度1％,50℃搅拌60 min,调pH值为4,升温至90℃,搅拌60 min.通过对上染工艺中的胭脂虫红色素浓度、染色温度、染色时间、pH值等影响因素进行单因素实验分析,得到了最佳的染色工艺:胭脂虫红色素浓度60％,pH值4,染色温度90℃,染色时间50 min,浴比1:40.     

蛋白酶法胭脂虫红色素的萃取及对柞蚕丝织物的染色

利用蛋白酶与水结合的方法对胭脂虫干体内的胭脂虫红色素进行萃取,并通过天然染料胭脂虫红色素对柞蚕丝织物进行染色。利用蛋白酶进行色素提取,过程具有温度低、萃取时间短、提取效果好等特点。通过对上染工艺中的胭脂虫红色素质量浓度、染色温度、染色时间、pH值等影响因素进行单因素试验分析,得到了最佳的染色工艺为:胭脂虫红质量浓度1.5 g/L,染色温度80℃,染色时间40 min,pH值为4,浴比1∶40。     

胭脂虫红色素的提取纯化工艺研究

以胭脂虫干体为原料,通过粉碎、浸提、树脂吸附、解吸浓缩、冷冻干燥等得到胭脂虫红色素粉末.以色素的吸光度值为指标,通过比较提取率的高低,对提取温度、提取时间、料液比、提取次数等因素进行了研究,确定胭脂虫红色素的最佳提取工艺条件为:提取温度85℃、浸提时间2h、料液比为1:60、提取次数为2次.通过静态吸附和解吸实验确定最佳的纯化树脂为S-8大孔吸附树脂.再通过静态和动态吸附、解吸实验对吸附率和解吸率进行研究,确定胭脂虫红色素的最佳纯化工艺条件为:上柱浓度为0.750×15、流速为2BV/h、pH为4;洗脱剂为pH2的60%的乙醇、洗脱流速为2BV/h.通过最佳提取工艺提取、最佳纯化工艺纯化、冷冻干燥得到色素粉末,其色价为102,胭脂虫红酸的含量达到了70.93%.     

超滤膜精制胭脂虫红色素的研究

用膜分离技术处理胭脂虫色素提取液,研究不同孔径的超滤膜对胭脂虫色素精制结果的影响,确定胭脂虫色素膜精制的方法。调节色素粗提液的pH值在4附近,静置24h后滤去沉淀,所得液体用截留分子量为5kD的螺旋卷式再生纤维素超滤膜进行精制,可以截留73％虫体蛋白,提高胭脂虫红色素的纯度,胭脂虫红酸含量可达54％。     

胭脂虫红色素对羊毛织物的染色性能研究

从染液pH值、染色温度、染色时间、染料提升性等方面入手对胭脂虫红色素上染羊毛织物的性能进行研究,并对染色牢度和生态安全性进行测试.研究结果表明,胭脂虫红色素上染羊毛的最佳工艺条件为:染液pH值3～4,染色温度为80 C以上,染色时间为50～60min;胭脂虫红色素对羊毛织物具有较好的提升性;胭脂虫红色素染色的羊毛织物的金属离子含量和禁用偶氮染料含量达到生态纺织品的要求.     

南极红色素与胭脂虫红色素稳定性对比

为了探究南极真菌Geomyces WNF-15A分泌的红色素的稳定性,通过与胭脂虫红色素的对比,包括色价、紫外敏感性、氧化剂还原剂的影响、食品添加剂的影响、金属离子稳定性、酸碱稳定性等方面,发现南极红色素在528 nm有最大吸收波长;色价为144.3;对紫外光稳定;对绝大多数金属离子稳定;pH值在6¹0内稳定。测试结果表明南极红色素稳定性较好,有成为胭脂虫红色素替代品的潜力。     

脂溶性胭脂虫红色素的制备及表征

为拓宽胭脂虫红色素在食品及日化品等领域中的应用,以月桂酰氯为改性试剂对胭脂虫红色素的主要成分--胭脂虫红酸进行分子结构修饰,制得脂溶性胭脂虫红色素。通过单因素试验及优化验证,确定了最佳制备条件为：以1.0 g胭脂虫红色素为原料,N,N-二甲基甲酰胺、月桂酰氯的用量分别为15.3 mL、4.5 g,反应温度42.0 ℃,反应时长1 h。在此条件下,胭脂虫红色素的回收率为59.35%。通过紫外-可见分光光度计、傅里叶变换红外光谱仪对脂溶性胭脂虫红色素的结构进行表征,表明胭脂虫红色素和月桂酰氯发生了酯化反应,生成了胭脂虫红酸月桂酸酯,并可溶于食用玉米油中,且稳定性较好,20 ℃条件下溶解度为15.06 g/100 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.