响应面法优化南极磷虾蛋白酶解物溶解性工艺

以南极磷虾蛋白酶解物的溶解性为指标,在单因素实验的基础上,采用响应面优化实验分析了南极磷虾蛋白酶解过程中酶与底物比、时间、温度、pH等因素对南极磷虾蛋白酶解物溶解性的影响,建立了南极磷虾蛋白酶解物溶解度与各因素的最佳工艺的回归模型并进行了验证。实验从4种酶中优筛选出木瓜蛋白酶作为酶解用酶,在此基础上,结合实际生产情况确定木瓜蛋白酶酶解南极磷虾蛋白的最适工艺为:酶与底物比0.25%(w/w)、酶解时间30 min、酶解温度55 ℃、酶解pH6.0,此时南极磷虾蛋白酶解产物的溶解度为12.06%±0.21%。因此,酶解改性能够改变南极磷虾蛋白的溶解性。     

南极磷虾酶解工艺优化及酶解产物对牡蛎肉的冷冻保护作用

为了开发安全高效的无磷抗冻剂,本研究以南极磷虾为原料制备酶解产物对其进行冷冻保护作用评价,为开发新型抗冻剂提供基础数据。以水解度为指标,对南极磷虾进行酶解,从4种蛋白酶中筛选得到碱性蛋白酶作为实验用酶,在单因素实验的基础上结合正交试验对酶解工艺进行了优化;并以解冻失水率、盐溶性蛋白含量、总巯基含量、Ca2+-ATPase酶活力为指标,考察了南极磷虾酶解产物对牡蛎肉的冷冻保护作用。结果表明,用碱性蛋白酶酶解南极磷虾的最佳条件为温度为55℃,酶解pH为8.5,加酶量2.6%,酶解时间为5 h;在此工艺参数下南极磷虾酶解产物相对分子质量主要分布在100~5500 Da,占总酶解产物的79.69%。南极磷虾酶解产物可以抑制牡蛎冻藏后失水,延缓盐溶性蛋白、Ca2+-ATPase酶活力、总巯基含量下降,其作用效果优于含磷抗冻剂。因此,南极磷虾酶解产物具有冷冻保护活性,可进一步对其进行分离鉴定研究。     

乙醇浸提法提取南极磷虾多酚物质研究

采用乙醇浸提法提取南极磷虾体内的多酚物质,应用单因素实验研究乙醇浓度、提取时间、提取温度、物料比等因素对多酚提取率的影响。在单因素实验基础上,通过四因素三水平Box-Behnken响应面分析法,建立二次多项回归方程,确立南极磷虾多酚物质的最佳提取条件为:乙醇浓度80%,提取时间70 min,提取温度35.5℃,物料比1∶10,在此条件下,南极磷虾多酚的提取得率为1.227 mg/g。     

太平洋磷虾油提取工艺优化及与南极磷虾油品质的比较

采用有机溶剂浸提法,增加了乙醇复溶步骤,分别对太平洋磷虾粉以及鲜太平洋磷虾进行油脂提取单因素实验和正交实验。以虾粉为原料,用95%乙醇分别提取太平洋磷虾油和南极磷虾油,对虾油中游离脂肪酸、虾青素、磷脂及脂肪酸组成进行分析和比较。结果表明:最佳提取溶剂为95%乙醇;对于鲜虾,提取的最佳工艺条件为提取温度45℃、料液比1∶12、提取时间3 h,在此条件下油脂得率为12.99%;对于虾粉,提取的最佳工艺条件为提取温度55℃、料液比1∶10、提取时间3 h,在此条件下油脂得率为20.00%;太平洋磷虾油磷脂含量高于南极磷虾油的,为39.53%;两种虾油虾青素含量接近;太平洋磷虾油游离脂肪酸含量略高于南极磷虾油的,为9.21%;太平洋磷虾油脂肪酸种类较多,两者EPA、DHA总含量接近,南极磷虾油EPA含量较高,太平洋磷虾油DHA含量较高。     

南极磷虾肽制备工艺优化及抗氧化测定

目的:优化南极磷虾肽的提取工艺。方法:选取料液比、加酶量、温度、pH以及时间5因素,在单因素实验的基础上采用L9(34)正交实验,计算各组酶解液的水解度。结果:正交分析软件得到木瓜蛋白酶对磷虾最佳的酶解条件为:料液比1:2,加酶量3000U/g,酶解温度55℃,酶解pH7.0,酶解时间3h,验证实验测得最优条件下水解度达24.73%。结论:酶解液经浓缩、喷雾干燥后,得到淡黄色具虾香味的粉末,得率6.48%,多肽含量达87.32%,通过与维生素E的比较,表明其在抗氧化方面具有良好的清除自由基的能力,说明该方法制备得到的南极磷虾肽在实际生产中有较为广阔的应用前景。     

响应面优化南极磷虾蛋白酶解工艺及蛋白肽组分分析

以南极磷虾蛋白酶解液中的氨基氮含量为指标,采用甲醛电位滴定法测定胰蛋白酶、木瓜蛋白酶、碱性蛋白酶、胃蛋白酶、风味蛋白酶、枯草杆菌蛋白酶6种生物酶在其最适酶解条件下对南极磷虾蛋白酶解效果,筛选出酶解南极磷虾蛋白最佳生物酶。在单因素试验基础上,以酶解液中氨基氮含量为响应值,选择酶解温度、时间、pH为自变量,通过三因素三水平Box-Bohnken响应面分析法对筛选出来的生物酶解工艺进行优化。在优化酶解工艺的基础上,利用SDS-PAGE凝胶电泳方法分析南极磷虾酶解蛋白肽及南极磷虾蛋白的分子量分布范围。结果表明:胰蛋白酶为酶解南极磷虾蛋白的理想蛋白酶;响应面分析法建立二次多项回归方程:Y=51.07-0.83A+1.72B-2.06C+0.25AC+1.15BC-3.06A2-2.77B2-3.69C2,模型p0.0001,而失拟项p0.05,表明模型极显著且比较稳定,通过模型分析得最佳条件:酶解温度44.48℃、酶解时间8.52 h、pH 7.88,考虑实际应用可行性,我们在酶解温度45.0℃、酶解时间8.5 h,pH 7.9条件下实验得到的氨基氮含量为50.96±1.07mg/g,与理论预测值51.57mg/g基本一致。通过电泳分析得到南极磷虾蛋白分子量范围在15 ku以上,主要集中分子量范围为15 ku～45 ku;胰蛋白酶解多肽分子量在25 ku以下,主要分子量分布在5 ku以下。     

南极磷虾油提取工艺的优化

对从南极磷虾中提取磷虾油的工艺条件进行研究。探讨了在不同的料液比、处理温度、处理时间和超声波功率对磷虾油提取率的影响。在单因素试验的基础上,选择四因素三水平进行正交试验优化工艺参数。结果表明,磷虾油的最佳提取条件为:时间3 h,温度35℃,料液比1∶7(g/m L),功率130 W,磷虾油得率为16.3%。     

南极磷虾蛋白粉的制备工艺

以南极磷虾为原料,研究其酶解及喷雾干燥工艺,以及南极磷虾蛋白粉的营养成分指标。研究结果表明,采用木瓜蛋白酶酶解南极磷虾的最佳工艺参数:每100 g南极磷虾肉糜中木瓜蛋白酶酶用量3 000 U/g蛋白、料液比为1∶2(g∶m L)、温度55℃、p H 6. 5、时间2 h;南极磷虾酶解液最佳喷雾干燥条件:进料量250 g/L、进风温度180℃、进料温度30℃、进料速度12 m L/min;南极磷虾蛋白粉为白色粉状,吸湿性较强。南极磷虾蛋白粉脂肪含量较低且具有丰富的矿物元素,关于南极磷虾及其高附加值产品的研究具有很强的开发前景。     

响应面优化复合酶酶解制备南极磷虾酱工艺研究

采用南极磷虾为原料,对复合酶酶解制备南极磷虾酱工艺进行研究。以南极磷虾酱的游离氨基氮(FAN)值为参考指标,确定木瓜蛋白酶和风味蛋白酶添加比例为按酶活力比2.5∶1同时添加;通过响应面分析法确定复合酶酶解制备南极磷虾酱的最佳工艺,即复合酶用量0.55%,食盐用量16.6%,酶解温度54.6℃,酶解时间3.9h,此时南极磷虾酱的FAN值达到0.56g/100g。     

响应面法优化南极磷虾蛋白酶解工艺条件

以水解度(DH)为考察指标,评价了中性蛋白酶、木瓜蛋白酶、胰蛋白酶及碱性蛋白酶酶解南极磷虾粉的效果,并选用水解效果最好的碱性蛋白酶作为试验用酶,探讨了碱性蛋白酶酶解温度、酶解时间、加酶量以及体系初始p H对水解度的影响。在单因素试验结果的基础上,采用响应面分析法优化了碱性蛋白酶酶解南极磷虾粉工艺。结果表明,最佳酶解工艺条件为酶解温度45.68℃、酶添加量1.67%、酶解时间5.47 h、pH为8.08,此条件下,南极磷虾蛋白粉水解度可达到15.27%。     

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