3种鲶鱼肌肉主要营养成分的对比分析

通过对斑点叉尾鮰、六须鲶、革胡子鲶肌肉的水分、总灰分、钙含量、粗蛋白和氨基酸构成、粗脂肪和脂肪酸构成等进行对比分析,为科学评估3种鲶鱼肌肉的营养品质提供基础数据。分析用样品取自鲶鱼背部肌肉,每种各测定25尾。结果显示,斑点叉尾鮰、六须鲶、革胡子鲶的水分含量分别为：75．5％,78．63％,71．86％,其中六须鲶水分含量显著高于斑点叉尾鮰和革胡子鲶,肉质较为细嫩;它们的肌肉总灰分含量分别为：1．16％,1．17％,1．10％,钙含量分别为：1．30,1．24,0．92mg／100g,六须鲶与斑点叉尾鮰的总灰分与钙含量均显著高于革胡子鲶;3种鲶鱼肌肉粗脂肪含量分别是6．78％,4．95％,11．88％,均有极显著差异,革胡子鲶最高,六须鲶最低,且以革胡子鲶所含有的脂肪酸种类最多,脂肪酸总量和必需脂肪酸含量最高;粗蛋白含量分别是：18,29％,17．06％,17．02％,其中斑点叉尾鮰极显著高于六须鲶和革胡子鲶;3种鲶鱼蛋白的氨基酸构成均为18种,其中斑点叉尾鮰的必需氨基酸及风味氨基酸含量、必需氨基酸评分最高。3种鲶鱼均是膳食中蛋白质、脂肪及无机盐的良好来源,与其他两种鲶鱼相比,斑点叉尾鮰更具有高蛋白、低脂肪的营养学优点,其蛋白质的营养价值最高。     

纤维素酶热稳定机制的计算分析

对水解糖苷酶第45家族的纤维素酶系进行计算分析,计算结果表明,与此家族酶系的热稳定性呈负相关的氨基酸对为:丙氧酸-谷氨酸(AE)、苯丙氨酸-赖氨酸(FK)和丙氨酸-异亮氨酸(AI);呈正相关的氨基酸对:甲硫氨酸-脯氨酸(MP)和甲硫氨酸-甘氨酸(MG),并引入氨基酸热稳定常量计算验证其相关性,发现呈负相关的氨基酸对均为显著相关,而呈正相关的氨基酸对显著性不明显.这个结果可以为此家族纤维素酶的基因工程改造提供一定参考.     

胃蛋白酶、胰蛋白酶提取革胡子鲶下脚料中卵磷脂的酶解条件比较

利用胃蛋白酶、胰蛋白酶分别对革胡子鲶下脚料进行预处理,采用乙醇溶剂提取法提取卵磷脂。通过单因素试验,比较了两种酶的酶添加量、酶解时间、酶解温度、酶解pH对革胡子鲶下脚料中卵磷脂提取的影响,其结果为:胃蛋白酶和胰蛋白酶的最佳酶添加量分别为0.075%、0.015%;最佳酶解时间均为80 min;最佳酶解温度均为37℃;最佳酶解pH分别为3,9,差异很大;分别在这些条件下,胰蛋白酶对卵磷脂提取的磷含量都高于胃蛋白酶。     

专家发现氨基酸混合物高效分离新方法

近日,中国农业科学院麻类研究所麻纤维产品与加工技术团队在聚离子液体膜分离氨基酸混合物研究方面取得重要进展。研究发现,聚离子液体膜具有良好的机械性能,对氨基酸的分离效果好且具有优良的抗菌性和抗污染性,该研究为氨基酸混合物分离工业应用提供了新方法。相关研究成果在线发表在《Journal of Colloid and Interface Science(胶体与界面科学)》上。据谭志坚研究员介绍,氨基酸被广泛应用于食品、饲料和医药等领域,蛋白质水解和微生物发酵是获得氨基酸的最常用的方法,但是往往获得的是氨基酸混合物。膜分离方法是分离氨基酸混合物的一种重要手段,聚离子液体膜与其他膜相比.     

氨基酸对大米淀粉糊化和流变性质的影响

以赖氨酸(lysine,Lys)、天冬氨酸(aspartic acid,Asp)和丙氨酸(alanine,Ala)分别代表带正电、负电、不带电3类氨基酸,采用快速黏度分析仪和流变仪研究氨基酸对大米淀粉糊化和流变性质的影响。结果表明,Lys和Asp均显著提高了大米淀粉的峰值黏度和崩解值(P0.05),但是降低了淀粉的最终黏度和回生值,而Ala对淀粉的糊化性质影响微小,在一定浓度范围内无显著差异(P0.05)。因此,带电的2种氨基酸(Lys和Asp)比不带电氨基酸(Ala)对淀粉糊化性质影响更强。此外,3种氨基酸对大米淀粉糊流变性质影响不同:动态流变学实验中,添加Lys和Ala使淀粉凝胶更具弹性,而Asp使淀粉凝胶变弱;静态流变学实验中,运用幂定律τ=kγm,对剪切应力τ和剪切速率γ进行了拟合,结果表明,原淀粉与添加氨基酸的淀粉的m值均小于1,表明淀粉及其氨基酸混合物都属于假塑性流体,并且Lys使淀粉假塑性增强,而Asp则相反。     

腊胡子鲶的研制

腊胡子鲶的研制但拥材,徐多思四川省川仁肉食品综合加工厂６１２５７５家养胡子鲶能吞吃肉联厂价格低廉的肺脏,养殖密度大,生长快,成本低,效益高,近年来,养殖量越来越大。我厂养殖四年,每年捕捞都在５千公斤以上。因不能过冬,多在初冬捕捞,个体重ｌ～３公斤。胡...     

氨基酸离子液体的制备及其催化Mannich反应研究

文章以氨基酸和硝酸为原料,合成两种氨基酸离子液体催化剂,将其用于催化Mannich反应,合成β-氨基羰基化合物。考察催化剂的种类、用量、反应温度和反应时间对Mannich反应的影响,以最优的条件进行反应底物的拓展。结果表明,L-丙氨酸硝酸盐离子液体L-[Ala]NO₃催化剂对于合成β-氨基羰基化合物具有良好的催化效果。     

焙烤对宁夏滩羊肉脂肪酸、氨基酸及核苷酸含量的影响

以宁夏盐池滩羊为研究对象，探究不同烤制时间对羊肉脂肪酸、氨基酸以及核苷酸含量的变化的影响。研究结果表明:烤制过程中，总蛋白质含量由19.92%上升到40.51%，总脂肪含量由3.51%上升到12.75%。总脂肪酸含量在烤制0~8 min增加，8~12 min降低，12~20 min再增加，差异不显著(P＞0.05)。在测出的25种脂肪酸中，油酸、硬脂酸和棕榈酸含量普遍较高，在100 mg/100 g以上。总水解氨基酸含量显著增加(P＜0.05)，由鲜羊肉中的18.5 g/100 g上升至49.42 g/100 g，其中以赖氨酸、亮氨酸和半胱氨酸增加最为明显。游离氨基酸中精氨酸、丙氨酸以及半胱氨酸含量上升，而组氨酸含量下降，其它游离氨基酸含量变化不显著(P＞0.05)。滋味活度值(TAV)法确定了烤制滩羊肉中关键的鲜味氨基酸为谷氨酸，关键甜味氨基酸为丙氨酸，关键苦味氨基酸为蛋氨酸、苯丙氨酸、缬氨酸、精氨酸。烤制滩羊肉中的主要滋味物质5''-腺苷酸和5''-鸟苷酸的含量随着烤制时间的延长呈现上升趋势(P＞0.05)。PCA分析表明滩羊肉中脂肪酸、水解氨基酸、游离氨基酸和核苷酸的含量在烤制过程中差异明显。     

复合氨基酸螯合钙的合成工艺优化

以鱼类加工下脚料鱼头、鱼排为原料制备复合氨基酸螯合钙,采用Plackett-Burman设计、最陡爬坡试验和中心组合设计法对螯合工艺条件进行优化。结果表明,pH值和氨基态氮对螯合率有显著影响(P<0.05),复合氨基酸液中氨基酸的种类及其含量对螯合效果影响较大,当氨基酸浓度大于2.1mg/mL时,螯合钙中相应的氨基酸相对含量也较高;在复合氨基酸液与钙液螯合时,甲硫氨酸和甘氨酸对钙的螯合能力均大于丙氨酸。优化后的螯合工艺参数:pH值7.90,温度50℃,时间60min,氨基态氮浓度为3.66g/L,复合氨基酸液∶钙液(V∶V)20∶1,该条件下螯合率为58.19%。     

不同发酵时间对燕麦酵素营养的影响及α-淀粉酶抑制效果动力学分析

以燕麦为原料,将其进行发芽处理制成燕麦酵素,研究其发酵过程中的β-葡聚糖、游离氨基酸、多酚及黄酮含量的变化,探究发酵过程中燕麦酵素对α-淀粉酶抑制效果及抑制类型,考察燕麦酵素中的营养素与α-淀粉酶抑制效果之间的相关性。结果显示：随着燕麦酵素发酵时间的延长,燕麦酵素中β-葡聚糖、游离氨基酸、多酚及黄酮含量均呈现上升趋势,发酵96 h达到最高;燕麦酵素对α-淀粉酶存在着抑制作用,最高抑制率达到72.27%,IC50=30.96 g/L,动力学分析得出：无论燕麦酵素浓度如何,对α-淀粉酶抑制类型均属于混合型抑制;通过相关性分析可知：燕麦酵素中多酚及黄酮含量与α-淀粉酶的抑制活性存在着显著正相关(P<0.05),β-葡聚糖含量、游离氨基酸含量与α-淀粉酶抑制作用的正相关性不明显(P>0.05)。燕麦酵素是一种开发前景广阔、营养丰富、具有一定抗氧化性的产品。     

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