玉米多肽的制备

以玉米蛋白粉为原料,经蛋白酶酶解、分离和提纯可制得玉米多肤.试验通过中性蛋白酶和木瓜蛋白酶复合酶来水解玉米蛋白粉制备多肽,对此工艺进行了研究,试验以水解度(DH)为指标,确定了复合酶解的最佳工艺条件为复合配比2:1、底物质量分数10%、pH值7.5、温度45℃、水解时间2 h,在此条件下水解度为20.38%.     

双酶法制备玉米肽酶解条件研究

利用双酶法水解玉米蛋白粉制备玉米肽,探讨各因素对水解度(DH)的影响,旨在确定玉米肽制备的最佳酶解条件。结果表明：最佳酶解条件为温度55℃、底物质量浓度5g/100mL、pH8.5,按4% 的酶与底物比加碱性蛋白酶水解1.5h 后,调整pH 值至7.5,之后再按3.5% 的酶与底物比加木瓜蛋白酶水解1.5h。在此条件下,水解液中DH 为80.97%。与单酶法相比,DH 明显提高。     

碱性蛋白酶水解脱脂玉米胚芽粕工艺的研究

研究了2709碱性蛋白酶水解脱脂玉米胚芽粕的最佳工艺.以脱脂玉米胚芽粕为原料,水解度为指标,在单因素试验的基础上,采用正交试验确定了脱脂玉米胚芽粕最佳水解工艺条件.得出最佳水解工艺条件为:底物浓度5％(占水的质量),加酶量5％(占底物的质量),水解温度45℃,水解pH 10.0,水解时间180 min.在此条件下,脱脂玉米胚芽粕的水解度为22.46％.     

二次回归通用旋转组合设计酶解法制备大豆肽的研究

利用碱性蛋白酶对大豆分离蛋白进行水解制备大豆肽,以水解度(DH)表征其反应程度,以单因素及二次回归通用旋转组合设计确定了大豆肽的水解条件模型及最佳条件为:温度为55℃,pH值为9.5,酶质量分数为6%,底物浓度为2%,水解时间为1.0h.在此条件下,水解液的大豆肽的溶氮指数(NSI)和水解度(DH)分别达到93.16% 和92.27%.     

双酶分步水解玉米蛋白粉制备玉米肽干粉的研究

利用碱性蛋白酶和木瓜蛋白酶双酶对玉米蛋白粉进行分步水解,确定制备玉米肽干粉的工艺流程.对双酶分步水解和单酶单独水解进行了蛋白质收率(X)和水解度(DH)的对比分析,同时对不同活性碳浓度对水解液脱色率和氮回收率的影响进行了讨论.     

大豆蛋白肽对面条质构和蒸煮品质的影响

在可控条件下制备了水解度(DH)为4％、7％和9％的大豆蛋白肽(SPP),以面粉质量3％替代面粉制备强化面条,考察SPP对面条品质的影响.结果 表明:在相同DH条件下制备的SPP强化面条其品质差异不大,其弹性、回复性和内聚性组间差异不明显,硬度、咀嚼性和拉断力略有差异,但其差异性小于不同DH条件下制备的强化面条.     

酶法水解玉米浆制备玉米肽的研究

文章以玉米浆为主要试验原料,进行酶法水解玉米浆制备玉米肽的研究,从酸性蛋白酶、中性蛋白酶、碱性蛋白酶和木瓜蛋白酶中筛选最适试验用酶,采用单因素试验确定最佳酶解条件,采用L_9(3~4)正交设计试验确定最佳因素组合。结果表明:以水解度(DH)为指标,中性蛋白酶水解玉米浆制备玉米肽水解度最高,当酶和底物比为3%(W/W)、pH 7.5、55℃下水解6h时,玉米浆的水解度最高,可达到44.5%。     

玉米蛋白粉水解工艺的研究

以玉米蛋白粉为原料,以水解度为检测指标,采用枯草芽孢杆菌发酵和木瓜蛋白酶水解相结合的方法制备高水解度的玉米多肽.研究结果表明,枯草芽孢杆菌发酵玉米蛋白粉的最佳条件为:选择菌龄为14 h的种子液,接种量为12％,发酵培养基的初始pH值为7.5.37℃培养24h,玉米蛋白粉水解度达12.85％;木瓜蛋白酶酶解玉米蛋白粉发酵液的最佳条件为:酶与底物比为6.0％,pH值为6.0,55℃条件水解4h,玉米蛋白粉水解度可达23.69％.     

玉米黄粉蛋白酶解过程的研究及产物分析

利用中性蛋白酶和复合风味蛋白酶对玉米黄粉蛋白进行酶解，研究了双酶法水解玉米黄粉蛋白的过程，并对水解产物进行分析。结果表明，双酶法水解玉米黄粉蛋白的最佳酶解条件为：pH＝6.7，T＝47℃，S%=0．9%，S／E复＝30，E复／E中＝8，水解时间40min，试验指标水解度(DH)％可达到32.82％，酸溶性多肽得率(YASP)％可达到87.46%，氮溶指数(NSI)％接近37.43％。经分析测定，水解产物中氨基酸含量4.84mg／g Pr，多肽含量18l.86mg／g Pr;多肽分子量主要分布于1089—1728Dal范围内。     

Alcalase蛋白酶水解法制备山核桃肽的研究

以脱脂山核桃渣为原料,利用Alcalase 蛋白酶对山核桃蛋白进行水解制备山核桃活性肽,以水解度(DH)表征其反应程度,确定其最佳水解条件为：温度55℃,pH9.0,底物浓度8%,酶质量分数6%,水解时间2.0h。在此条件下水解度(DH)为76.16%。     

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