洋葱皮中黄酮化合物的超声提取与光谱分析

采用超声波法从洋葱皮中提取黄酮类化合物并探讨出最佳提取条件,建立了洋葱皮中黄酮化合物的光谱分析方法.实验结果表明:此光谱分析法的回收率为99.6%～102.1%,变异系数小于0.18%。     

洋葱中黄酮类化合物的提取方法研究

目的确定洋葱中黄酮类化合物的最优提取方法。方法分别用正交法确定热水浸提法、乙醇浸提法和酶解提取法提取洋葱中的黄酮类化合物的最佳工艺,以提取物中的黄酮含量为指标,得出最佳提取方案。结果酶解提取法提取效率最高,其最佳提取工艺为酶解pH 5、酶解温度40℃、酶量2.7‰、酶解时间70 min。在此工艺条件下,提取物中的黄酮含量可达到5.8649 mg/g。结论洋葱中黄酮化合物的最佳提取方法为酶解法为最佳提取方法,此结果可为洋葱中的黄酮提取物的工业化生产提供技术参考。     

洋葱皮中类黄酮不同提取工艺的比较

以不同提取方法制备的洋葱皮中总黄酮提取率作为考察指标,对乙醇回流提取法、超声提取法和微波提取法提取洋葱皮黄酮类化合物的效果进行比较,结果表明微波提取法对洋葱皮类黄酮的提取率最高,进一步的正交试验确定了微波提取洋葱皮中总黄酮的最佳工艺参数:微波辐射时间150 s、微波功率240 W、料液比1:35、乙醇体积分数60%。该条件下的洋葱皮类黄酮提取率达到了6.138%,较超声提取法和乙醇热回流法提取率得到了大幅度的提高。     

洋葱中总黄酮微波提取法

利用微波快速提取洋葱中黄酮类化合物,采用正交实验L9(34),优化实验条件,考察了提取剂浓度、微波提取时间、微波功率、料液比等因素对洋葱中黄酮类化合物提取的影响,确定了微波法提取洋葱中黄酮类化合物最佳的工艺条件.与传统的回流法进行比较.微波提取法具有提取效率高、所需时间短、提取溶剂用量少、操作方便、便于推广普及等优点,亦可用于其它样品的提取分析.     

三种洋葱营养成分分析

对三种洋葱的主要营养成分、矿物质和黄酮类化合物含量进行分析研究,并探讨黄酮类化合物含量与抗氧化的关系。三种洋葱中水分含量为88.3%～92.7%,碳水化合物为7.73%～8.56%,蛋白质为1.12%～1.71%,脂肪为0.23%～0.41%,其中,白皮洋葱的脂肪含量较高,适合作为提取洋葱油的原料。三种洋葱中黄酮类化合物含量为592.3～913.2mg/kg,紫皮洋葱的黄酮类化合物含量最高,适合作为提取黄酮类化合物的原料,而且紫皮洋葱的产量较高,种植面积较大,很有开发前景;三种洋葱的黄酮类化合物含量与总的抗氧化能力没有相关性。三种洋葱矿物质元素组成相似,钾含量最高,铜含量最低。     

棚栽与野生苣荬菜中黄酮含量的分析

采用超声波法提取棚栽与野生苣荬菜中黄酮类化合物并探讨出最佳提取条件,建立了苣荬菜中黄酮化合物的光谱分析方法并对棚栽与野生苣荬菜中黄酮进行了分析。实验结果表明方法的回收率为107%～109%,变异系数小于0.58%。棚栽与野生苣荬菜中黄酮的含量分别为22.21mg/kg和20.64mg/kg。     

微波辅助萃取-HPLC测定洋葱槲皮素技术的研究

目的优化洋葱中槲皮素的提取条件。方法以洋葱中槲皮素为指标,用高效液相色谱法测定,采用正交实验设计L934优化实验条件,并且对比研究了微波辅助提取法MAE与普通加热回流和室温浸渍法提取洋葱中槲皮素的提取率。结果确定了MAE提取洋葱中槲皮素的最佳条件为:粒度60～90目,水分含量为25%,功率为100W,萃取时间为10min。提取时间为普通加热回流的1/12倍,室温浸渍法的1/144倍。优化的MAE提取洋葱中槲皮素提取产率分别比普通加热回流和室温浸渍法提高约31%和36%。结论MAE不仅提取率高,而且提取时间大大缩短,是一种适合于洋葱中槲皮素快速高效的提取方法。     

真空冷冻干燥和热风干燥对洋葱挥发性成分的影响

采用同时蒸馏萃取的方法提取新鲜洋葱、真空冷冻干燥洋葱和热风干燥洋葱的挥发性成分,并经气质联用分析,分别析出36、33、27种物质。鉴定出洋葱的挥发性成分主要包括含硫化合物、有机酸、醚、醛、酯、烃类化合物,新鲜洋葱中的挥发性物质在真空冷冻干燥和热风干燥过程中分别保留了14、12种物质,其总峰面积含量分别为55.59%、53.16%。真空冷冻干燥洋葱更利于洋葱干燥品质的提高。     

洋葱中黄酮类化合物的提取与测定

采用乙醇提取洋葱中的黄酮类化合物,用紫外-可见分光光度法测定提取的黄酮类化合物的质量。考察乙醇浓度、料液比、提取时间、提取温度对黄酮类化合物提取量的影响。结果表明,测定波长为504 nm,芦丁检测浓度在0.080 mg/mL~0.400 mg/mL范围内与吸收度线性关系良好(R2=0.997 4);用乙醇提取洋葱中黄酮类化合物的工艺条件为乙醇浓度60%,料液比1∶18(g/mL),提取时间2.5 h,提取温度77℃。在此工艺条件下,从6.00 g洋葱中提取黄酮类化合物的量为25.40 mg。     

洋葱中黄酮类化合物的提取及其体外抗氧化活性研究

对洋葱中黄酮类化合物提取的最佳工艺条件及其体外抗氧化活性进行了研究.在提取过程中通过单因素试验分析了乙醇浓度、液料比、提取温度、提取时间对提取率的影响.在此基础上通过正交试验得到了洋葱黄酮类化合物提取的最佳工艺条件,即乙醇浓度70%,液料比20 ∶ 1,温度70℃,时间1.5h.体外抗氧化实验结果表明洋葱黄酮类化合物具有较强的还原力,对超氧阴离子自由基和羟自由基具有较强的清除能力,即洋葱黄酮类化合物具有较强的体外抗氧化活性.     

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.     

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.     

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.     

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     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press