酶法提高白葡萄酒质量稳定性的研究

利用木瓜蛋白酶水解白葡萄酒中非稳定蛋白,通过大量试验,确定了酶反应最佳条件为：加酶量为0．6％（w／v）,酶反应pH6．5,在45℃反应38h。此条件下,白葡萄酒中的蛋白含量降低为0．31g／L,氨基酸含量升高至6．7mg／L。     

白葡萄酒废酵母蛋白及多糖的提取工艺研究

本实验主要研究了从白葡萄酒废酵母中提取蛋白和多糖的方法。结果表明:经处理后的酵母悬浮液在超声波功率600W,作用时间4s,间歇时间2s,作用90次的条件下,促溶效果最好。经超声波处理后,再添加0.6%(W/V)的木瓜蛋白酶,在55℃,pH5.5下,反应时间为30h,提取液中蛋白含量达到9.84g/L。提取蛋白后的残渣,用碱法提取多糖,含量达58.69%。     

木瓜蛋白酶水解海洋鱼鳞蛋白的工艺研究

研究了木瓜蛋白酶水解鱼鳞蛋白的单一影响因素,并采用L9(34)正交实验,考察了温度、时间、酶量、底物浓度等因素对水解鱼鳞蛋白的影响.确定了木瓜蛋白酶水解鱼鳞蛋白工艺条件,即温度65℃,时间75 min,酶量0.04 g/g鱼鳞,底物浓度10％,适合规模化生产.     

超声辅助木瓜蛋白酶改性对米糠蛋白溶解性和乳化性的影响

采用超声辅助木瓜蛋白酶改性技术提高米糠蛋白溶解性和乳化性。首先米糠蛋白在超声功率密度5 W/m L、超声时间30 min、蛋白质量浓度4 g/100 m L条件下进行预处理,然后通过单因素实验优化了酶反应条件。结果表明:最佳酶反应条件为酶添加量2. 5 g/100 m L、酶反应时间3 h、pH 7、酶反应温度50℃;改性后米糠蛋白溶解性和乳化活性增强,乳化稳定性降低;改性后米糠蛋白二硫键、α-螺旋和β-转角含量减小,表面疏水性、β-折叠和无规则卷曲含量升高,表明超声辅助木瓜蛋白酶改性破坏了蛋白质空间结构,进而改善了米糠蛋白溶解性和乳化性。     

大米蛋白抗氧化肽的酶法制备工艺研究及其优化

以大米蛋白粉为反应底物,采用酶解法制备大米蛋白抗氧化肽。以酶解液的水解度与对DPPH自由基的清除率为指标,从中性蛋白酶、碱性蛋白酶、木瓜蛋白酶3种蛋白酶中筛选出木瓜蛋白酶为最佳用酶。通过BoxBehnken响应面设计法优化木瓜蛋白酶酶解大米蛋白抗氧化肽的工艺条件为p H值5.25、酶解温度61.4℃、加酶量5.6 U/m L、底物质量浓度5.3 g/100 m L。其酶解液稀释5倍后对DPPH自由基的清除率为94.8%。     

木瓜蛋白酶水解羊乳酪蛋白的工艺研究

目的:研究木瓜蛋白酶酶解羊乳酪蛋白的最优工艺条件,以获得具有抗菌活性的酶解物.方法:以山羊乳为原料制备酪蛋白,以木瓜蛋白酶为水解酶对其进行水解,通过单因素试验和正交试验,以酶解液中氨基态氮含量为指标,优选木瓜蛋白酶酶解山羊乳酪蛋白的最佳工艺条件,并用该酶解物做抑菌活性试验.结果:木瓜蛋白酶酶解山羊乳酪蛋白的最佳酶解工艺:酶与底物比4 000 U/g,底物质量浓度85 g/L,初始pH 6.0,在温度60 ℃下酶解150 min.抗菌试验结果表明,酶解液氨基氮质量浓度为0.2889 g/100 mL时,对Ecoli.O157有一定的抑菌活性.结论:用木瓜蛋白酶酶解山羊乳酪蛋白,可得到具有一定抑菌活性的酶解物.这是获得抗菌肽的良好来源.     

玉米醇溶蛋白酶解工艺的研究

利用木瓜蛋白酶和复合风味酶对玉米醇溶蛋白碱性蛋白酶解液进行酶解,通过单因素试验和正交试验方法确定双酶法水解的最适条件为:底物质量浓度为70 g/L时,温度55℃,pH为6.0,木瓜蛋白酶用量为5%(E/S),风味酶用量为4.5%(E/S),水解时间2 h.在此条件下氨基态氮含量可达到2.5654 mg/mL.     

大枣多糖脱蛋白的研究

讨论采用大枣多糖酶制剂法脱蛋白的最佳工艺条件,试验确定为:温度60℃,pH5.0,浓度10g/L木瓜蛋白酶酶液与多糖液的体积比为0.4:1,酶解时间90 min,蛋白除去率为91.8%.     

沙城产区陶罐发酵雷司令干白葡萄酒品质及香气成分分析

以沙城产区雷司令葡萄为原料制备干白葡萄酒,对照陶罐发酵和不锈钢罐发酵干白葡萄酒理化指标、香气成分和感官分析。结果表明,陶罐发酵雷司令干白葡萄酒总糖、总酸、挥发酸及干浸出物含量分别为3.05 g/L、7.05 g/L、0.10 g/L、20.8 g/L,其酒精度和pH值（10.35%vol、3.30）低于不锈钢罐发酵雷司令干白葡萄酒（11.65%vol、3.34）（P＜0.05）;陶罐和不锈钢罐发酵干白葡萄酒均检测出81种香气物质,陶罐发酵雷司令干白葡萄酒气味活力值（OAV）＞1的物质有11种,以萜烯类为主,特征香气为花香;不锈钢罐发酵雷司令干白葡萄酒OAV＞1的物质有15种,特征香气为果香。陶罐发酵雷司令干白葡萄酒的感官评分（95.3分）高于不锈钢罐发酵雷司令干白葡萄（92.2分）。结果显示,陶罐发酵雷司令干白葡萄酒的品质较好。     

木瓜蛋白酶酶解猪骨素蛋白工艺的研究

在单因素实验基础上,通过正交实验探讨了木瓜蛋白酶酶解猪骨骨素蛋白的工艺条件.结果显示,在本实验条件下,木瓜蛋白酶酶解猪骨骨素蛋白的最佳工艺为:温度55℃,pH6.5,加酶量10000U/g,料液比1:12.5g/mL,酶解3h,此条件下水解度可以达到16.95%.     

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