紫外-可见分光光度法测定火龙果花中总黄酮的含量

研究火龙果花中黄酮类化合物的分离提取和测定方法。在单因素实验的基础上,利用正交实验对分离提取条件进行优化。结果表明,最佳分离提取条件为:乙醇浓度为70%,固液比为1∶40(g/m L),提取温度为75℃,提取时间为2 h;以芦丁为标准品,采用Al Cl3显色-分光光度法测得火龙果花中总黄酮含量为0.747%,样品平均回收率为99.51%,RSD值为2.06%(n=5)。     

大孔树脂吸附纯化火龙果茎黄酮类化合物的研究

以紫外分光光度法为检测手段,采用静态吸附分离法优选分离火龙果茎中黄酮类化合物的大孔树脂;并用动态吸附分离法对分离条件进行研究.结果表明D101大孔树脂对火龙果茎总黄酮有良好的吸附解吸分离性能,其动态分离纯化条件为:火龙果茎中总黄酮的上样液浓度为820mg/L,最大上样量为75mL(4倍湿树脂体积).吸附速度为2.0mL/min,用70%乙醇以2.0mL/min的速度洗脱,洗脱率可达99.21%,经纯化后的产物中总黄酮纯度为70.61%,为纯化前的5.11倍.     

芫荽中黄酮类化合物的提取及其体外抗氧化活性研究

目的:确定芫荽中黄酮类化合物的最佳提取条件,比较芫荽不同部位的抗氧化活性。方法:采用正交实验确定芫荽中黄酮类化合物提取的最佳方案,以芦丁为对照品,用紫外分光光度计分别测定其根、茎、叶的黄酮类化合物含量,采用Fenton反应体系产生·OH与邻苯三酚自氧化产生O2-及对DPPH自由基消除作用,研究芫荽根、茎、叶提取液对三者的清除作用。结果:最佳提取条件为:乙醇浓度为70%、温度为90℃、提取时间为2.5h。芫荽根、茎、叶的黄酮类化合物含量分别为:13.00mg/m L、20.00mg/m L、102.00mg/m L。芫荽根、茎、叶提取液对·OH、O2-及DPPH自由基均有清除作用。结论:芫荽的根、茎、叶均具有较强的抗氧化活性,且芫荽根、茎、叶对·OH、O2-及DPPH自由基的消除能力均为:叶根茎,即根、茎、叶抗氧化活性的大小为:叶根茎。     

从西芹中提取黄酮类物质最佳条件的研究

采用乙醇有机溶剂提取法,分别提取西芹叶和茎中的黄酮类物质,并用分光光度法测定黄酮类物质的含量.再通过对提取温度、回流时间、物料比、乙醇浓度四个提取因素筛选,最后通过正交实验得出西芹叶子中提取黄酮类物质最佳条件是:提取温度85℃,回流时间3h,物料比1:20,乙醇浓度85%;茎中提取黄酮类物质最佳条件是:提取温度75℃.回流时间3h,物料比1:12,乙醇浓度90%.     

豆瓣酱中黄酮类物质的测定

实验研究了豆瓣酱中黄酮类化合物的提取与测定.采用正交实验确定了豆瓣酱中黄酮类化合物的最佳提取条件为:乙醇浓度60%、固液比1∶20、提取温度50 ℃、提取时间3 h.并采用分光光度法测定所提取样品的吸光度,获得总黄酮的最大含量为0.0629 mg/g.     

超声微波协同提取甘薯叶中黄酮类化合物的研究

采用超声微波协同提取法,以黄酮类化合物为考察指标,通过单因素实验和正交实验研究出超声-微波协同乙醇提取甘薯叶黄酮的最佳工艺条件:乙醇浓度为80%,超声功率为300W,超声时间3min,微波功率150W,微波时间3min,液料比为1∶60。在此条件下甘薯叶黄酮类化合物的提取率可达8.61%。选择聚酰胺柱层析分离,用乙醇梯度溶液以2mL/min的速度洗脱,收集各浓度乙醇的洗脱液浓缩点样,确定黄酮中各类物质,干燥称重,槲皮素的含量在1.62%以下。     

荷梗中黄酮类化合物提取工艺的研究

利用单因素试验和正交试验研究了以乙醇作为溶剂对荷梗中黄酮类化合物的提取工艺以及对不同季节荷梗中黄酮类化合物含量进行研究。确定最佳工艺条件为:提取温度70℃、乙醇浓度75%、料液比为1:30、时间3h.,黄酮类化合物的得率为0.582%。9月份的含量最高。     

花生壳中黄酮类化合物的提取及其纯化

本实验采用微波法对花生壳中黄酮类化合物进行提取。将单因素分析与正交试验相结合,得到微波法提取花生壳中黄酮类化合物的最佳工艺条件：提取剂乙醇体积分数50%,微波功率700W,提取时间4min,料液比1:30(g/ml),每克花生壳中提取黄酮类化合物为0.48mg,回收率为93.3 %。微波法与乙醇回流法相比提取时间由4h减少到4min,提取黄酮类化合物的量提高了2.4倍。大孔吸附树脂富集纯化花生壳黄酮类化合物方法：以木犀草素作为考察指标,考察静态吸附量和洗脱率,筛选出最适型号树脂,比较纯化前后黄酮类化合物和木犀草素含量的变化。结果表明：D101型树脂为花生壳提取液最佳精制纯化树脂,树脂纯化后黄酮类化合物和木犀草素的含量提高4～5倍。     

南瓜茎黄酮的微波提取及抗氧化性能研究

采用单因素法确定了微波辅助提取南瓜茎黄酮的最佳工艺条件为:以70%乙醇作溶剂,料液比1 ∶ 20,70℃,400W微波提取3min,效果最好,提取率为0.333%.提取物经AB-8树脂纯化后,进行了特殊的颜色反应实验和抗氧化实验,颜色反应结果进一步证实了提取物中黄酮类化合物的存在,抗氧化实验表明南瓜茎黄酮对猪油有较强的抗氧化活性.     

新疆长穗柽柳总黄酮提取工艺研究

新疆长穗柽柳中含有黄酮类化合物,本实验采用分光光度法,以芦丁为标准样品测定长穗柽柳茎中的总黄酮的含量,结果表明黄酮类化合物的最佳提取工艺为:乙醇浓度40%、提取时间1h、固液比1:50、提取温度80℃。实验结果可能为今后长穗柽柳资源的开发利用提供重要的理论依据。     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the