蓝圆鲹鱼肉蛋白酶解条件的确定

以水解液中α-氨基态氮含量为指标,选用木瓜蛋白酶、碱性蛋白酶、中性蛋白酶和动物蛋白水解复合酶对蓝圆鲹鱼肉进行单酶水解,确定中性蛋白酶为水解用酶。利用正交实验确定的水解条件为:加酶量1300IU/g、温度55℃、酶解时间6h、底物浓度为33%。在此条件下水解率为47%。      

蓝圆鲹鱼肉蛋白酶解条件的确定

以水解液中α-氨基态氮含量为指标,选用木瓜蛋白酶、碱性蛋白酶、中性蛋白酶和动物蛋白水解复合酶对蓝圆鲹鱼肉进行单酶水解,确定中性蛋白酶为水解用酶.利用正交实验确定的水解条件为:加酶量1300IU/g、温度55℃、酶解时间6h、底物浓度为33%.在此条件下水解率为47%.     

酶解中国毛虾制备水解蛋白的工艺研究

对中国毛虾的一般营养成分进行了分析。以水解液中α-氨基态氮含量为指标,选用木瓜蛋白酶、碱性蛋白酶、风味酶和复合动物蛋白酶对中国毛虾进行单酶水解,确定风味酶为水解用酶。通过正交实验确定风味酶的水解条件为:温度55℃、pH6·5、水解时间6h、酶浓度4%、料∶水=1∶5。验证实验表明,水解液中α-氨基态氮含量为1·187g/100g。水解液经浓缩、喷雾干燥,得到淡黄色、具浓郁虾香味的粉末。      

酶解中国毛虾制备水解蛋白的工艺研究

对中国毛虾的一般营养成分进行了分析.以水解液中α-氨基态氮含量为指标,选用木瓜蛋白酶、碱性蛋白酶、风味酶和复合动物蛋白酶对中国毛虾进行单酶水解,确定风味酶为水解用酶.通过正交实验确定风味酶的水解条件为:温度55%、pH6.5、水解时间6h、酶浓度4%、料:水=1:5.验证实验表明,水解液中α-氨基态氮含量为1.187g//100g.水解液经浓缩、喷雾干燥,得到淡黄色、具浓郁虾香味的粉末.     

超声波辅助酶法水解寻氏肌蛤蛋白

采用超声波辅助中性蛋白酶水解寻氏肌蛤,以-氨基态氮含量为检测指标。首先采用单因素和正交优化试验L9(34)确定酶法水解薄壳肉蛋白的最适条件.研究结果为:pH6.5,水解时间5 h,温度55℃,酶浓度2.0%,料液比1∶2,水解液的α-氨基态氮含量为0.372 6 g/100 mL。在此基础上,研究功率300 W的超声波预处理对酶解效果的影响,综合考虑,采用超声波预处理10 min,α-氨基态氮含量提高到0.394 1 g/100 mL。     

黄鳍金枪鱼头蛋白酶解条件的研究

确定了中性蛋白酶、木瓜蛋白酶、风味酶两两组合双酶水解金枪鱼头蛋白的最佳组合,利用正交试验探讨了酶浓度、温度、水解时间对双酶水解效果的影响,确定了最佳的水解条件。结果表明:木瓜蛋白酶和中性蛋白酶双酶同时水解金枪鱼头蛋白的效果最好;最佳水解条件下水解液的氨基酸态氮含量为126.53mg/100mL,氮回收率为80.2%;水解液氨基酸分析表明,水解液的氨基酸总量为4.12g/100mL,其中必需氨基酸占36.04%,游离氨基酸为0.81g/100mL。     

酶法水解牛胎盘下脚料

以牛胎盘下脚料为原料，试验5种蛋白酶对其进行水解，根据水解液综合效果确定中性蛋白酶为最适单酶，其最佳水解条件为温度40℃，pH7．5，酶添加量4000u／g，料水比1：3，水解时间4h；响应面分析方法知，中性蛋白酶与胰蛋白酶混合水解牛胎盘下脚料的最佳水解条件为：温度46．4℃，pH值为8．17，酶比1：1(酶量为4000u／g)，料水比为1：3。氨基酸分析结果表明：混合酶水解液的游离氨基酸2483.6mg／L，而中性酶水解液的游离氨基酸493.8mg／L。     

蛋白酶水解糯米酒糟的工艺优化

分别采用酒用酸性蛋白酶、木瓜蛋白酶水解糯米酒糟,优化提高水解液中氨基态氮含量的工艺条件。不同蛋白酶的水解实验结果表明,酒用酸性蛋白酶的水解效果最理想。糯米酒糟水解的最优条件为:加酶量2 000 U/g酒糟、料液比1∶3、pH3.5、温度40℃、时间5 h。在此工艺条件下,水解液中氨基态氮含量达到0.75 g/L,比初始糯米酒糟液提高了368.75%。     

双酶法水解双孢蘑菇蛋白的工艺研究

实验研究了纤维素酶和中性蛋白酶共同水解双孢蘑菇蛋白的水解工艺,以α-氨基氮含量为指标,确定了纤维素酶和中性蛋白酶的最佳水解条件为:先加纤维素酶,料液比1∶20,加酶量250 U/g,初始pH值6.0,酶解温度55℃,酶解时间120 min;后加中性蛋白酶,加酶量1500U/g,初始pH值6.5,酶解温度45℃,酶解时间150 min.经双酶水解后,α-氨基氮含量可达36.96mg/g.     

铬革屑的酶解研究及其产物氨基酸成分分析

根据水解率确定了中性蛋白酶水解铬革屑的最佳条件,系统考察了水解温度、水解时间、酶用量、浴液pH对水解率的影响,通过正交试验优化了中性酶水解铬革屑的条件,得到最佳水解条件为:温度55℃,水解时间4 h,酶用量2%,浴液pH=7.0;在此条件下水解率为94.25%,氮收率达78.84﹪,水解液中铬含量仅为0.31×10-4g/L。并通过高效液相色谱(HPLC)分析了最佳实验条件下水解产物中的游离氨基酸成分。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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