超声波辅助提取玫瑰花色素及其稳定性研究

目的确定超声波辅助提取玫瑰花色素的最佳条件,探索pH值、温度、光线、食品添加剂(淀粉、抗氧化剂、防腐剂)、金属离子对玫瑰花色素稳定性的影响。方法采用超声波辅助法提取玫瑰花色素,通过正交试验确定最佳提取条件。根据玫瑰花色素吸光值的变化研究pH值、温度、光线、食品添加剂、金属离子对玫瑰花色素稳定性的影响。结果最佳工艺条件为:65%乙醇提取、料液比1:160(m:V)、超声波功率500 W、超声波处理30 min、提取1次、提取量为29.505 AV。玫瑰花色素在酸性条件下稳定,且温度、光线、防腐剂、过氧化氢、食品基质、Ca2+对玫瑰花色素稳定性影响不大,而硫代硫酸钠和Fe3+会对其稳定性产生较大的影响。结论该研究可为玫瑰花色素的开发利用提供理论支持。     

茼蒿色素的提取工艺及稳定性研究

对茼蒿天然色素的提取方法及稳定性进行研究.通过不同溶剂提取效率比较,确定水为最佳提取溶剂.对水提取茼蒿色素的温度、pH值、料液比和时间进行单因子试验与正交设计试验,确定最佳提取工艺条件为pH5.0,温度50℃,料液比1:20,提取时间5 h.茼蒿色素的稳定性研究表明,其耐高温、耐光性较好,在酸性条件下较为稳定,在碱性条件下变色:不同金属离子对色素稳定性影响不大,糖类食品添加剂和氧化还原剂对色素稳定性有较大影响.     

金盏菊花中色素的提取工艺及稳定性研究

目的：确定金盏菊花色素的最佳提取工艺,并对其稳定性进行研究。方法：以浸提法对金盏菊花中的色素进行提取,通过对提取剂、料液比、提取温度、提取时间4因素进行,L9(34)正交试验得到最佳提取条件;同时考察光照、热和食品添加剂等对色素稳定性的影响。结果：金盏菊花色素最佳提取工艺为提取剂90%乙醇、料液比1:8(g/mL)、在70℃水浴中浸提40min;该色素在酸性条件下稳定性较好,对光和热稳定性好;pH值对色素的稳定性影响较大,在酸性条件(pH5)下该色素较稳定;常用食品添加剂如葡萄糖、蔗糖对色素的色泽无不良影响,金属离子Na+、Mg2+、Ca2+、Cu2+对金盏菊花色素无不良影响,而Fe3+则对色素有明显影响。结论：获得金盏菊花中色素提取的最佳工艺;色素对光、热、常用食品添加剂的稳定性良好,为其在食品和药品中的应用提供了广阔的前景。     

朱砂七色素提取及其稳定性研究

本文以中药朱砂七为原料,通过提取溶剂的选择和料液比、提取温度和提取时间的单因素分析,选取不同因素水平进行正交实验,以紫外—可见分光光度计法测定吸光度,以吸光度值为考察指标进行分析.同时研究了光照、温度、pH、氧化剂和还原剂、食品添加剂和金属离子对朱砂七色素的稳定性影响.结果表明:朱砂七色素最佳提取工艺为:70％乙醇为浸提溶剂,料液比1:6,50℃时浸提90min;朱砂七色素光稳定性、热稳定性和耐氧化性较好,低浓度的还原剂溶液中色素的耐还原性较好,在弱酸至中强度碱(6 ＜pH＜10)条件下稳定,对葡萄糖和柠檬酸等食品添加剂稳定,碳酸氢钠有不良影响,金属离子Na+、Zn2+、Mg2+、K+对色素几乎没有影响,Ca2、Fe3、Cu2+对色素有较大影响.     

石榴皮原花青素的微波提取工艺及其稳定性研究

采用微波法提取野生石榴皮中的原花青素,同时考察光照、温度、金属离子、PH及食品添加剂对原花青素稳定性的影响。通过单因素试验和正交试验得出微波提取石榴皮原花青素的最佳工艺条件为：乙醇浓度80％、料液比1：50、提取温度65℃、微波功率500W、提取时间120s、提取2次,原花青素的得率为2．62％。稳定性研究表明,光照条件下色素稳定性较差;高温对色素有降解作用,60℃以下稳定性良好;pH值为5时色素稳定性好;金属离子Cu^2＋和Al^3＋对原花青素的稳定性影响显著;苯甲酸对原花青素稳定性影响显著。     

菝葜根茎色素的提取及稳定性研究

该试验对菝葜根茎色素的最佳提取条件和色素的稳定性进行探究性试验。把单因素试验结果作为试验基础,以吸光度作为检测指标,通过采用L9(33)正交试验设计,验证试验对菝葜根茎色素的提取工艺条件进行最佳优化,同时探究其氧化还原剂、金属离子等因素对菝葜根茎色素稳定性的影响。结果表明,最佳提取工艺为提取温度70℃,提取液浓度50%乙醇,提取时间1.5 h,料液比为1∶10(g/mL)。稳定性试验结果表明加入氧化剂H2O2和还原剂Na2SO3对菝葜根茎色素的吸光值有上升趋势;金属离子检测时Fe3+对色素有显著影响,其他金属离子对菝葜根茎色素液的影响不明显。     

枇杷皮色素的稳定性研究

为了从枇杷皮中提取色素并研究其稳定性,以枇杷皮为原料,以乙醇为浸提剂,用微波法提取色素,研究在不同金属离子、pH值、光照时间、温度、食品添加剂和氧化剂、还原剂等条件下的稳定性。结果表明,光照时间和pH值对色素稳定性的影响较大,而金属离子、温度、食品添加剂、氧化剂、还原剂等对色素的影响相对较小。枇杷皮色素在不同金属离子、食品添加剂、氧化剂和还原剂中有较好的稳定性。     

葡萄皮色素的提取及稳定性研究

研究葡萄皮色素的提取工艺及稳定性.结果表明:葡萄皮色素耐光、耐热性好,在酸性介质中可稳定存在且有较强的增色作用.同时还研究了食品中常用的几种食品添加剂、各种金属离子、pH值、光等对葡萄皮色素稳定性的影响及该色素的耐氧化还原性等,为葡萄皮色素在食品、医药工业中的开发、利用提供了理论依据.     

西梅果皮色素的提取工艺及其稳定性研究

通过L9(34)正交试验确定了西梅果皮色素的最佳提取工艺;同时考察了光照、温度、氧化还原剂、酸碱和食品添加剂等对其色素稳定性的影响.结果表明,色素最佳提取工艺为:提取剂0.5%盐酸乙醇,浸提温度70℃、浸提时间5h,料液比1:10;西梅果皮色素紫红色,该色素对光和熱稳定性较好,常用食品添加剂如糖类、山梨酸钾、苹果酸钠对色素的色泽无不良影响,Zn2 、K 、Ca2 、Mg2 、Na 和Cuz 对西梅果皮色素无不良影响,pH值对色素的稳定性影响较大,在酸性条件(pH<4)下该色素较稳定,Fe3 、氧化还原剂、日光对该色素有一定减色作用.     

千里光花黄色素提取及稳定性研究

采用有机溶剂浸提法,以千里光花黄色素特征吸光度值为指标,探讨了千里光花黄色素的提取条件和稳定性。结果表明:用1:25的乙酸乙酯在60℃恒温浸提3h为最佳提取工艺条件;该色素为脂溶性色素,在强酸中极不稳定,而在碱性条件下稳定;高温对该色素的稳定性影响不明显,强日光和紫外光会加快色素降解,室内自然光对该色素的稳定性影响不明显;强氧化剂对该色素的稳定性影响不明显,还原剂对该色素的稳定性有一定影响;苯甲酸钠、蔗糖、可溶性淀粉和盐等常用食品添加剂对该色素的稳定性无影响;金属离子Cu2+、Al3+、Fe3+对该色素的稳定性影响显著,Na+、K+、Ca2+、Zn2+等离子对该色素的稳定性无影响;该色素为功能性植物色素,可广泛应用于食品、医药和化妆品等行业。     

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.     

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.     

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.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.