大豆粉末磷脂的酶解工艺及产物性能研究

研究了放线菌型磷脂酶A2在水相中酶解大豆粉末磷脂的工艺条件,确定了最佳工艺组合为底物浓度10%,Ca2 浓度10mmol,温度40℃,初始pH值7.5,水解时间19h,磷脂转化率达43.3%;同时从宏观和微观两角度对酶解磷脂的乳化性能进行了研究,结果表明:酶解磷脂的乳化稳定性约为粉末磷脂的3倍,相同乳化能力下用量可减少50%,达到氧化平衡时的过氧化值为粉末磷脂的41.0%。     

磷脂酶A1催化大豆粉末磷脂水解工艺研究

利用磷脂酶A1对大豆粉末磷脂进行水解,研究了反应温度、加酶(PLA1)量、反应时间、加水量及搅拌速度对磷脂酶A1水解大豆粉末磷脂的影响.通过单因素试验确定的最佳反应条件为:反应温度60℃,加酶量8%,反应时间8 h,加水量5 mL,搅拌速度500 r/min.在此条件下产物酸价可以达到101.4mgKOH/g.     

溶血磷脂乳化稳定性研究

研究大豆粉末溶血磷脂乳化稳定性,并与原料大豆粉末磷脂进行比较;结果表明,在不同的pH、温度、离子强度、油水比条件下,大豆粉末溶血磷脂乳化稳定性远优于大豆粉末磷脂。     

脂酶催化下大豆粉末磷脂与全氢化大豆油酯交换反应的研究

本文利用脂酶的特异性催化作用,研究了正己烷体系中,大豆粉末磷脂与全氢化大豆油的酯交换反应。利用碘值和产率为指标,考察了酶的种类及用量、底物摩尔比、温度、时间等因素对酯交换反应的影响,通过单因素和正交试验优化了大豆粉末磷脂与全氢化大豆油酯交换反应条件。发现在25%磷脂酶A1(以磷脂质量为基准)催化下,摩尔比4:1的全氢化大豆油和大豆粉末磷脂的正己烷溶液(磷脂浓度为0.20 g/mL),在50 ℃下反应24 h,得到产率为72.9%的改性磷脂。与原料磷脂相比,改性磷脂的碘值由89 g /100 g降至52 g /100 g,脂肪酸组成变化较大,硬脂酸含量约为原料磷脂的9倍,不饱和脂肪酸亚麻酸和亚油酸含量降低了约一半,实现了大豆粉末磷脂的结构修饰。     

酶法制备甘油磷酸胆碱的研究

研究了水相体系中磷脂酶A<,1>水解大豆粉末磷脂制备甘油磷酸胆碱(GPC)的可行性,探讨了反应条件对磷脂酰胆碱(PC)转化率和GPC得率的影响.确定磷脂酶A<,1>催化制备GPC的最佳反应条件为:在pH 7的150 mL磷酸盐缓冲溶液中,粉末磷脂添加量5 g、CaCl2添加量0.50 g、酶添加量0.50 mL,温度55 ℃,反应时间6 h;利用LC-MS分析最佳条件下的反应液,得到PC转化率为98%,GPC得率达到95%;同时验证了在磷脂酶A<,1>催化制备GPC的过程中生成的溶血磷脂(LPC)Sn-2位不饱和脂肪酸发生了酰基转移,转移到Sn-1位.     

磷脂在面条中的应用研究

本试验采用磷脂酶A2催化酸解大豆粉末磷脂获得溶血磷脂，将两种磷脂添加到面条中，并对面条进行蒸煮试验和质构品质测定。结果表明，添加磷脂的面条，爽滑性、韧性、黏连程度均有改善，蒸煮时间降低，干物质损失率减小。溶血磷脂对面条品质的改良效果明显优于大豆粉末磷脂。     

酶改性大豆磷脂乳化稳定性比较

大豆浓缩磷脂、酶改性大豆浓缩磷脂、酶改性大豆粉末磷脂作为乳化剂经均质制备乳化液（油／水=1：1），调乳化液pH值分别为（3、5、7、9），常温下4h、80％3保温4h、分别添加0．1％NaCl和0．05％CaCl2，常温下放置4h后比较各乳化液的稳定性。添加大豆浓缩磷脂的乳化液受环境影响较大，在碱性或酸性较强条件下稳定性差。而添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂乳化液在pH值5～9下都保持良好的乳化稳定性，在pH值3时亦保持较好的乳化稳定性。在温度80℃条件下，添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂，在不同pH值时，乳化能力和乳化稳定性明显好于浓缩大豆磷脂。添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂的乳化液，在较高的离子强度下，保持有良好的乳化稳定性。而高离子强度对大豆浓缩磷脂的乳化性影响非常大，尤其在添加CaCl2的情况下，大豆浓缩磷脂几乎失去了乳化能力。在几种条件下，添加酶改性粉末大豆磷脂的乳化液稳定性最好。     

富含共轭亚油酸磷脂的制备工艺

采用甲醇钠为催化剂,以大豆粉末磷脂和共轭亚油酸乙酯为原料,通过酯交换反应制备富含共轭亚油酸磷脂。通过研究反应温度、反应时间、催化剂用量、共轭亚油酸乙酯与大豆粉末磷脂摩尔比对反应的影响,得出最优制备工艺条件为:反应温度130℃,反应时间3 h,催化剂用量为大豆粉末磷脂质量的4%,共轭亚油酸乙酯与大豆粉末磷脂摩尔比4∶1。在最优制备工艺条件下得到的磷脂产品中共轭亚油酸总含量可达59.23%,其中两种主要异构体c9,t11-CLA和t10,c12-CLA的含量分别为27%和29%左右。     

酶改性大豆磷脂乳化稳定性比较

大豆浓缩磷脂、酶改性大豆浓缩磷脂、酶改性大豆粉末磷脂作为乳化剂经均质制备乳化液(油/水=1∶1),调乳化液pH值分别为(3、5、7、9),常温下4h、80℃保温4h、分别添加0.1%NaCl和0.05%CaCl2,常温下放置4h后比较各乳化液的稳定性。添加大豆浓缩磷脂的乳化液受环境影响较大,在碱性或酸性较强条件下稳定性差。而添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂乳化液在pH值5￣9下都保持良好的乳化稳定性,在pH值3时亦保持较好的乳化稳定性。在温度80℃条件下,添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂,在不同pH值时,乳化能力和乳化稳定性明显好于浓缩大豆磷脂。添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂的乳化液,在较高的离子强度下,保持有良好的乳化稳定性。而高离子强度对大豆浓缩磷脂的乳化性影响非常大,尤其在添加CaCl2的情况下,大豆浓缩磷脂几乎失去了乳化能力。在几种条件下,添加酶改性粉末大豆磷脂的乳化液稳定性最好。     

有机相酶促粉末磷脂制备溶血磷脂的研究

选用磷脂酶A1为工具酶,以响应面为数值分析方法,在正己烷有机相中进行了大豆粉末磷脂水解制备溶血磷脂研究。探讨了反应时间,反应温度,加酶量,底物浓度,加水量,pH对其反应的影响。结果表明,溶血磷脂制备优化条件为:反应时间12.1 h,反应温度45℃,加酶量3%,底物浓度20.8%,加水量23.8%,pH 6。该条件下验证得溶血磷脂酸值(KOH)为77.8 mg/g。所得产物中磷脂酰胆碱和1-酰基-溶血磷脂酰胆碱含量分别为15.51%和3.99%,且2-酰基-溶血磷脂酰胆碱相对含量为19.6%。     

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