荧光光谱法检测微藻中油脂

研究了尼罗红染色荧光光谱法检测微藻中油脂含量的方法.探讨了染色时间、尼罗红质量浓度、二甲基亚砜体积分数、细胞密度对藻液细胞发射光谱的影响,得到最佳测定条件为:染色时间6min,尼罗红质量浓度0.8 μg/mL,二甲基亚砜体积分数20%,细胞密度(0.248～0.448)×10<'9>个/mL.该研究为规模化筛选高含油量藻株及跟踪产油微藻油脂积累过程奠定了基础.     

尼罗红荧光光谱法快速测定解脂耶氏酵母油脂含量的研究

为了建立快速简便检测解脂耶氏酵母油脂含量的方法,探讨了尼罗红-光谱法测定解脂耶氏酵母油脂含量的检测条件。通过研究解脂耶氏酵母最佳发射光波长、细胞密度、尼罗红染液用量、染色时间、不同助溶剂效能及最佳体积分数对荧光强度的影响,确定了最佳检测条件,得到细胞油脂含量与荧光强度的线性关系。解脂耶氏酵母在激发光560 nm、发射光650 nm处有最高荧光值,每毫升菌液加入质量分数为0.1 mg/m L的尼罗红染液20μL,加入体积分数为15%的异丙醇,黑暗染色5 min,在细胞OD600=0~1.3的范围内,菌液的油脂含量(X)与荧光值(Y)呈较好的线性关系,线性关系式为Y=6.3651X+10.097,R2=0.9902,灵敏度达0.0001 g。该方法能够准确地反映出解脂耶氏酵母胞内油脂含量。尼罗红-荧光法可成为一种快速检测解脂耶氏酵母胞内油脂含量的新方法。     

尼罗红-荧光光谱法测定亚心形扁藻油脂含量

尼罗红-荧光光谱法能够快速地对微藻细胞中的油脂含量进行检测,但是该方法对所测微藻物种具有一定依赖性,在分析不同微藻细胞油脂含量前需要对测试条件进行优化。优化后的亚心形扁藻油脂含量分析条件为:藻液800×g离心5 min去除培养基,用体积分数4%的二甲基亚砜(DMSO)水溶液重悬至OD750=0.3,尼罗红质量浓度0.8μg/m L,避光40℃水浴恒温10 min,激发波长520 nm。发现亚心形扁藻在培养的对数生长后期油脂开始积累,稳定期后期油脂含量趋于恒定,优化后的尼罗红-荧光光谱法能够准确地检测亚心形扁藻生长过程中的油脂含量变化。     

裂殖壶菌胞内油脂尼罗红荧光染色快速检测方法的研究北大核心CSCD

为了建立快速检测裂殖壶菌胞内油脂的方法,探讨了尼罗红荧光染色法检测裂殖壶菌油脂含量的检测条件。通过考察裂殖壶菌重悬液中添加二甲基亚砜体积分数、尼罗红染液用量、染色温度、染色时间及细胞密度对荧光强度的影响,确立最优检测条件,进一步考察细胞油脂含量与荧光强度的关系,从而建立尼罗红荧光检测法的定量关系。结果表明,最优检测条件为：每毫升裂殖壶菌重悬液中二甲基亚砜体积分数和尼罗红染液用量分别为25%和15μL,染色温度50℃,染色时间15 min。在最优检测条件下,细胞密度不超过0.218×10^8个/m L范围内,菌液油脂含量（X）与荧光强度（Y）呈现良好的线性关系,其线性关系式为Y=798.55X-3.44,相关系数R2为0.996 4。因此,采用尼罗红荧光染色法可以快速检测裂殖壶菌的油脂含量。     

裂殖壶菌胞内油脂尼罗红荧光染色快速检测方法的研究

为了建立快速检测裂殖壶菌胞内油脂的方法,探讨了尼罗红荧光染色法检测裂殖壶菌油脂含量的检测条件。通过考察裂殖壶菌重悬液中添加二甲基亚砜体积分数、尼罗红染液用量、染色温度、染色时间及细胞密度对荧光强度的影响,确立最优检测条件,进一步考察细胞油脂含量与荧光强度的关系,从而建立尼罗红荧光检测法的定量关系。结果表明,最优检测条件为:每毫升裂殖壶菌重悬液中二甲基亚砜体积分数和尼罗红染液用量分别为25%和15μL,染色温度50℃,染色时间15 min。在最优检测条件下,细胞密度不超过0.218×10~8个/m L范围内,菌液油脂含量(X)与荧光强度(Y)呈现良好的线性关系,其线性关系式为Y=798.55X-3.44,相关系数R2为0.996 4。因此,采用尼罗红荧光染色法可以快速检测裂殖壶菌的油脂含量。     

基于尼罗红荧光染色的小球藻脂质快速检测方法研究

尼罗红荧光染色的脂质测定方法已经应用到一些种类的微藻当中,但在细胞壁较厚的一些绿藻中因不易染色而无法应用.选用了4株小球藻,对尼罗红荧光染色测定脂质的方法进行改进,采用20％二甲基亚砜溶液作为渗透剂,在35 ～ 40℃下对藻细胞进行前处理,加强尼罗红与胞内脂质的结合;藻细胞密度的OD540在0.8～1.1范围内,加入15 μL质量浓度为0.1 mg/mL的尼罗红丙酮溶液染色可以有效提高荧光发射强度.该方法能够较为准确地反映胞内脂质含量,可以作为自然界中广泛筛选富脂绿藻的快速检测方法.     

尼罗红-荧光光谱法测定布朗葡萄藻油脂含量的方法研究

布朗葡萄藻因胞外分泌物多、细胞壁厚、聚集生长等原因,不能用传统的尼罗红染色方法进行油脂含量测定。通过探索染色前处理和染色条件,优化了布朗葡萄藻的染色方法:藻液摇匀后超声波处理3 min(超声波参数为温度20℃、发射功率100 W、频率40 k Hz),3 000×g离心去除培养基,用体积分数8%的DMSO重悬细胞,调整悬液OD750到0.16,每1 m L样品加入10#L 120μg/m L的尼罗红丙酮溶液(尼罗红质量浓度1.2#g/m L),40℃水浴锅中染色10 min,荧光激发光波长520nm。改进的方法促进了尼罗红与布朗葡萄藻的结合,提高了测定的稳定性和准确度。     

红树林富油微藻的筛选及鉴定

采用尼罗红染色和油脂提取相结合的方法从海南东寨港红树林海水样品中,分离获得一株富油海洋微藻,油脂含量达36.43%,油脂产量为0.186 g/L。利用扫描电镜形态观察与分子鉴定相结合的技术手段,确定了该富油微藻属于红球藻属的Rhodella maculata。     

溶剂法提取微拟球藻脂质的工艺优化及其脂质组学分析

研究了溶剂法提取微拟球藻脂质的工艺,对比了氯仿-甲醇（体积比1∶?1）、氯仿、异丙醇、石油醚、正己烷-乙醇（体积比1∶?1）、正己烷、乙醇7种溶剂对微拟球藻脂质得率和二十碳五烯酸（EPA）含量的影响,确定乙醇作为提取溶剂。采用单因素试验研究了乙醇体积分数、料液比、提取温度和提取时间对微拟球藻脂质提取的影响,并通过正交试验对工艺条件进行优化,最后采用UPLC-Q-TOF-MS对所得微拟球藻脂质进行脂质组学分析。结果表明,微拟球藻脂质最佳提取工艺条件为乙醇体积分数80%、料液比1∶?17.5、提取温度65?℃、提取时间2 h。在最佳工艺条件下,微拟球藻脂质得率为（1587±0.21）%,EPA含量为（14.49±0.14）g/100 g。微拟球藻脂质中检出17种脂质,其中12种脂质含有EPA,含有EPA的脂质占总脂质的45.24%。     

植物激素对微拟球藻油脂及二十碳五烯酸积累的影响

考察了6种植物激素对微拟球藻油脂积累与EPA产量的影响,并初步探讨了其对油脂合成的调控机制.每种植物激素对微拟球藻油脂积累都有促进效果.其中添加20mg/L IBA时油脂产量提高最多,油脂质量分数提高20.94%.其次是添加15mg/L的BA,油脂质量分数提高20.34%.同时,BA在质量浓度为15mg/L时,EPA质量分数提高了29.34%.实时定量PCR证实BA等激素能显著提高微拟球藻中油脂合成相关基因的转录水平.证实了植物激素可用于提高微拟球藻EPA的产量,为利用植物激素提高微拟球藻发酵生产EPA提供了实验依据.     

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.