不同鸡肉蛋白肽在Maillard反应中的降解趋势研究

研究了鸡肉蛋白酶解3、6、9、12h产物中不同鸡肉蛋白肽(分子量<10000Da)与葡萄糖Maillard反应中肽降解的趋势。结果表明,不同鸡肉蛋白肽中相同分子量范围的肽段在Maillard反应中的降解趋势相同;而随着酶解程度的加大,鸡肉蛋白肽中各肽段的反应活性增加,12h酶解产物中的鸡肉蛋白肽各肽段均具有最高的反应活性。      

不同鸡肉蛋白肽在Maillard反应中的降解趋势研究

研究了鸡肉蛋白酶解3、6、9、12h产物中不同鸡肉蛋白肽(分子量<10000Da)与葡萄糖Maillard反应中肽降解的趋势。结果表明,不同鸡肉蛋白肽中相同分子量范围的肽段在Maillard反应中的降解趋势相同;而随着酶解程度的加大,鸡肉蛋白肽中各肽段的反应活性增加,12h酶解产物中的鸡肉蛋白肽各肽段均具有最高的反应活性。     

Alcalase降解水不溶性鸡肉蛋白规律及其产物清除DPPH活性研究

研究了Alcalase降解水不溶性鸡肉蛋白的规律及其产物清除DPPH自由基活性。结果表明,随酶解时间延长,可溶性蛋白质、氨基酸含量不断增加,而肽含量则在水解前8h达到最大,随后不断降低;肽的分子量分布趋势总体表现为大分子量的肽逐渐减少,小分子量肽的含量逐渐增多,肽分子量分布图中肽峰值不断向后推移;Alcalase对分子量在3000～15000Da间的肽段降解能力较弱,水解24h后,这部分肽占总肽量的比值仍为89.93%。水不溶性鸡肉蛋白Alcalase酶解产物有明显的清除DPPH活性,其清除DPPH活性在酶解4h时达到最大,随后不断下降;对于同一酶解时间的产物,浓度越大,其清除DPPH活性越强,但其清除DPPH能力并不与酶解液浓度成倍数关系。      

胰酶水解猪皮胶原蛋白及其产物氨基酸分析

采用胰酶水解猪皮胶原蛋白,研究其降解规律及酶解产物氨基酸组成.研究表明:95℃热处理猪皮胶原蛋白10 min能显著提高酶解速率;整个酶解过程中,可溶性氮、氨肽氮含量呈增加趋势,但3 h后增势变缓,而肤含量在3 h后达到最大值;大部分不溶性蛋白在酶解6h后已经变成可溶性多肽和氨基酸;从酶解产物氨基酸组成可表明,采用胰酶水解猪皮胶原蛋白能显著提高其营养价值.     

琥珀酸脱酰胺对小麦面筋蛋白酶解特性的影响

研究琥珀酸不同脱酰胺程度对小麦面筋蛋白Pancreatin酶解过程中蛋白回收率、水解度、总酸、总糖的影响,并对酶解48h酶解液的肽分子量分布、氨基酸及风味进行分析评价。结果表明:蛋白回收率、水解度、总酸在酶解过程中逐渐上升,总糖含量在酶解12h后下降,脱酰胺后酶解产物的蛋白回收率和水解度增大,而高脱酰胺程度下又略有降低;琥珀酸脱酰胺后酶解产物分子量大于10000Da的肽段减少,3000～5000Da的肽段增加;琥珀酸脱酰胺使酶解产物风味明显提高,其中琥珀酸高脱酰胺程度预处理的酶解液苦味最低,且具有较强的鲜味和咸味;氨基酸分析表明,琥珀酸高脱酰胺预处理使酶解液游离氨基酸中鲜甜味氨基酸比例增大,苦味氨基酸比例降低,同时必需氨基酸含量升高。      

琥珀酸脱酰胺对小麦面筋蛋白酶解特性的影响

研究琥珀酸不同脱酰胺程度对小麦面筋蛋白Pancreatin酶解过程中蛋白回收率、水解度、总酸、总糖的影响,并对酶解48h酶解液的肽分子量分布、氨基酸及风味进行分析评价.结果表明:蛋白回收率、水解度、总酸在酶解过程中逐渐上升,总糖含量在酶解12h后下降,脱酰胺后酶解产物的蛋白回收率和水解度增大,而高脱酰胺程度下又略有降低;琥珀酸脱酰胺后酶解产物分子量大于10000Da的肽段减少,3000～5000Da的肽段增加;琥珀酸脱酰胺使酶解产物风味明显提高,其中琥珀酸高脱酰胺程度预处理的酶解液苦味最低,且具有较强的鲜味和成味;氨基酸分析表明,琥珀酸高脱酰胺预处理使酶解液游离氨基酸中鲜甜味氨基酸比例增大,苦味氨基酸比例降低,同时必需氨基酸含量升高.     

复合酶法制备鸡肉蛋白抗氧化肽模型研究

以酶解产物对O-2·的清除率为指标,分析中性蛋白酶和木瓜蛋白酶的协同作用,确定制备鸡肉蛋白抗氧化肽的最佳复合酶解工艺,并对复合酶解过程进行酶促动力学特性研究。结果表明:复合酶解制备抗氧化肽最佳工艺为两酶混合同时加入,pH6·7,温度57℃,底物浓度6·9%,时间5h,酶用量为中性蛋白酶4943u/g、木瓜蛋白酶5988u/g,该条件下鸡肉蛋白抗氧化肽对O-2·的清除率为57·50%,显著高于各单酶水解效果。在此基础上由实验数据推导出描述复合酶制备鸡肉蛋白抗氧化肽水解过程的动力学方程,为鸡肉蛋白开发抗氧化肽提供理论依据。      

正交试验优化长吻鮠肉蛋白酶解工艺

以脱脂长吻鮠肉蛋白为原料,利用碱性蛋白酶酶解制备水解鱼肉蛋白。通过单因素试验和正交试验优化确定酶解的工艺参数,并考察酶解产物的氨基酸组成和分子量分布特征。结果表明,碱性蛋白酶对长吻鮠肉蛋白酶解最佳工艺参数为加酶量2.0%、温度60℃、pH 8.0、酶解时间4 h,在此条件下,水解度可达27.14%。长吻鮠肉蛋白酶解产物中谷氨酸、天门冬氨酸、赖氨酸和亮氨酸含量相对较高,其中必需氨基酸约占33.44%,酶解产物分子量分布范围主要集中在500~5 000 Da,占总酶解产物的78.3%。     

鸡肉蛋白酶解条件及产物降解规律

采用木瓜蛋白酶水解鸡肉蛋白,通过单因素实验和正交实验确定水解鸡肉蛋白的最适条件,并在此水解条件下酶解24 h,研究水解过程中酶解液中游离氨基酸含量和肽分子质量分布的变化规律。结果表明,最佳的酶解条件为:温度45℃,pH6.5,酶用量6.0%,固液比1∶2,水解时间6 h;酶解产物中游离氨基酸种类齐全且含量较高,水解过程中,游离氨基酸总量变化呈增长的趋势,16 h后变化不大;酶解液的肽分子质量都集中在3 000Da以下,酶解过程中大分子质量肽不断减少,小分子质量肽不断增加;酶解24 h后,分子质量小于1 000 Da的小分子肽和氨基酸含量可达97.19%。     

鸡肉抗疲劳蛋白肽粉的制备研究

研究了鸡肉酶解产物的抗疲劳活性.通过比较木瓜蛋白酶、风味蛋白酶、复合蛋白酶、砌胜蛋白酶和胰蛋白酶对鸡肉蛋白的酶解效果,酶解过程和成本,可知选用木瓜蛋白酶在温度为55℃,加酶量为4‰(以鸡肉质量百分数计算),固液比为1:2,pH值为7.0,酶解时间为3 h时进行酶解最为合理,其水解度为15.324%.将酶解液过滤、去油、浓缩、喷雾干燥制备出鸡肉蛋白肽粉,并送去检验部门进行检验,同时做动物实验检验蛋白肽粉的抗疲劳效果.动物实验过程是:将昆明种雄性小白鼠分为低、中、高的鸡肉蛋白肽粉(1.67,3.33,10.00g/kg BW)三个剂量组灌胃30d,测定小鼠负重游泳时间、尿素氮含量、血乳酸含量和肝糖原含量.结果表明,灌胃高剂量鸡肉蛋白肽粉小鼠的负重游泳时间延长,同时高剂量组肝糖原含量明显高于对照组(P<0.05),对小鼠运动后血清尿素氮含量与对照组比较没有统计学意义(P>0.05);而中、高剂量小鼠运动后血乳酸含量明显比对照组有明显降低(P<0.01).可见鸡肉蛋白肽粉有缓解体力疲劳功能.     

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