酶解小麦面筋蛋白及其组分功能特性研究

利用木瓜蛋白酶对谷朊粉功能特性进行改良,在pH7.0的条件下,研究时间对水解度的影响以及水解度对乳化活性和溶解度的影响,水解度为2.4%时,乳化活性可以达到72.5%.通过响应面实验,研究酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和溶解性的影响,探索木瓜蛋白酶水解谷朊粉提高乳化性和溶解性的最佳反应条件,分析发现5个因素对谷朊粉乳化性的影响由强到弱的顺序为酶浓度、谷朊粉浓度、时间、温度和pH值.最佳水解条件为:酶浓度0.475%、反应温度60℃、反应时间1.63 h、pH6.6、底物浓度4%,此时的水解度为4.32%、乳化活性为63.4%、溶解度则为19.04%.经过超滤(10 ku)后得到的截留组分乳化活性与酶解面筋蛋白接近.     

碱性蛋白酶水解提高谷朊粉乳化性的研究

利用碱性蛋白酶对谷朊粉乳化性进行改良，研究了酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和乳化稳定性的影响，在此基础上通过正交实验，探索碱性蛋白酶水解谷朊粉提高乳化性的最佳反应条件。分析发现五个因素对谷朊粉乳化性的影响由强到弱的顺序为：底物浓度、反应时间、酶浓度、pH值和反应温度。最佳水解条件为：底物浓度为10．0％，反应时间为4h，pH值为8．0，反应温度为60℃；此时谷朊粉的水解度为3．2％，乳化活性为77．02％，乳化稳定性为78．56％，比水解前乳化性有明显提高。     

利用转谷氨酰胺酶提高谷朊粉乳化性研究

转谷氨酰胺酶是一种催化蛋白质分子交联酶类,利用其对谷朊粉乳化性进行改良,研究酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和乳化稳定性影响;在此基础上通过正交实验,探索转谷氨酰胺酶酶解谷朊粉提高乳化性最佳反应条件。分析发现五个因素对谷朊粉乳化性影响由强到弱顺序为:pH值、谷朊粉浓度、温度、时间和酶浓度。最佳酶解条件为:谷朊粉浓度为6.0%,酶浓度1.0%,反应时间为1.0h,pH值为5.0,反应温度为45℃;此时谷朊粉乳化活性为84.9%,乳化稳定性为85.7%,比酶解前谷朊粉乳化性有明显提高。     

碱性蛋白酶对谷朊粉改性的研究

利用碱性蛋白酶对谷朊粉进行改性,研究了底物浓度、酶浓度、温度、pH值对谷朊粉乳化性的影响,在此基础上通过正交试验,探索碱性蛋白酶水解谷朊粉提高溶解度、水解度、乳化性及乳化稳定性的最佳反应条件。最佳水解条件为：底物浓度8.0%、pH值8.5、反应温度60℃、酶浓度0.09%。此时谷朊粉的溶解度为24.77%,水解度为12.73%,乳化性为71.43%,酶解效果显著。     

湿热处理提高谷朊粉乳化性的研究

以谷朊粉为原料，研究了利用湿热处理对谷朊粉乳化性的改善作用，通过pH值、谷朊粉质量分数、加热温度及时间对谷朊粉乳化性的影响，确立了4因素3水平的正交实验，探讨了湿热处理提高谷朊粉乳化性的最佳条件。结果表明：各因素对提高谷朊粉乳化性的明显程度依次为：pH值＞谷朊粉质量分数＞温度＞时间。正交试验分析表明，湿热处理提高乳化性的最佳作用条件为：pH值为4．0、谷朊粉质量分数为9．0％、时间为20min和温度为100℃。在最佳条件下，谷朊粉的乳化活性及乳化稳定性均为100％，溶解度为48．4％。说明湿热处理显著提高了谷朊粉的乳化性。     

微波处理提高谷朊粉乳化性的研究

以谷朊粉为原料，研究了利用微波处理对谷朊粉乳化性的改善作用，通过pH值，谷朊酚浓度，微波能量及加热时间对谷朊粉乳化性的影响，确立了四因素三水平的正交实验，探讨了微波处理提高谷朊酚乳化性的最佳条件。结果表明：各因素对提高谷朊粉乳化性的明显程度依次为：加热时间＞pH值＞谷朊粉浓度＞微技能量。正交试验分析表明，微波处理提高乳化性的最佳作用条件为：pH值＝10．0、谷朊粉浓度＝9．0％、加热时间=100和微波能量＝560W。在最佳条件下，谷朊粉的乳化活性及乳稳定性均为100％，溶解度＝37．6％。说明微波处理显著提高了谷朊粉的乳化性。     

盐酸处理对谷朊粉理化性质改良的研究

利用盐酸处理改善谷朊粉的溶解度、乳化性、起泡性等理化性质,研究盐酸与谷朊粉的相对浓度、反应温度、反应时间、盐酸浓度对谷朊粉理化性质的影响。结果表明,盐酸处理改良谷朊粉理化性质的最佳条件:谷朊粉质量百分比为8%,盐酸∶谷朊粉为3.5∶100(质量比),反应温度65℃。试验证明,盐酸处理对谷朊粉的溶解度、乳化性及其稳定性、起泡性及其稳定性都有显著作用。     

乳糖改性提高谷朊粉乳化性研究

研究了谷朊粉与乳糖在控制条件下通过Maillard反应对谷朊粉乳化性的改善作用。结果表明,乳糖改性明显地改善了谷朊粉的乳化活性(Emulsion Activity Index,EAI), 通过正交实验,得到Maillard反应改善谷朊粉乳化性的最佳条件为:pH7、谷朊粉/乳糖比为3:1、谷朊粉浓度为12%、反应时间为10d,此条件下的EAI为33 02m2/g;由方差分析可得,各因素对提高谷朊粉乳化性的重要性按大小次序为pH>谷朊粉/乳糖比>谷朊粉浓度、反应时间,通过方差分析显示诸因素对乳化性的影响没有显著差异。     

复合蛋白酶水解提高谷朊粉乳化性能的研究

利用复合蛋白酶对谷朊粉(WG)进行酶解改性,从而达到提高谷朊粉乳化性的目的。采用分光光度法研究了底物浓度、酶浓度、反应时间、p H和温度对WG的乳化性能的影响,在此基础上,采用响应面法优化复合蛋白酶水解提高谷朊粉乳化性能的最佳改性条件。分析发现各因素对提高谷朊粉乳化性能的显著程度依次为:酶浓度、底物浓度、时间、p H。在酶解温度固定50℃的条件下,优化出最佳改性工艺为底物浓度8%,反应时间3.5 h,酶浓度1 210 U/g,p H 6.5,得到酶解谷朊粉的乳化活性指数EAI和乳化稳定指数ESI分别为94.5 m L/g和30.42 min,较水解前显著提高。     

复合蛋白酶法提高谷朊粉溶解性研究

利用复合蛋白酶对谷朊粉(WG)进行酶解改性,从而达到提高谷朊粉溶解性的目的。采用分光光度法研究了底物浓度、酶浓度、反应时间、pH值和温度对WG的溶解性能的影响,在此基础上,采用响应面法优化复合蛋白酶水解提高谷朊粉溶解性能的最佳改性条件。在酶解温度固定50℃的条件下,最终得到最佳改性参数分别为:底物浓度8.21%、反应时间3.47 h、加酶量1203 U/g、pH值6.4,得到酶解谷朊粉的PDI为32.73%,较水解前显著提高。     

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