应用固定化木瓜蛋白酶制备大豆肽的研究

以壳聚糖为载体,用戊二醛交联将木瓜蛋白酶固定化,研究水解大豆分离蛋白制备大豆肽的工艺条件,结果表明:固定化木瓜蛋白酶的表观米氏常数为8.9 mg/mL.固定化木瓜蛋白酶的最适温度为55℃,最适pH为7.8,最佳底物浓度为2.0～3.0 mg/mL,大豆分离蛋白的最佳流速为0.2 mL/min,大豆分离蛋白的水解率达到42.6%,酶解液中大豆肽含量为1.453 mg/mL.酶解液多肽分子质量大部分在10 ku以下.     

固定化胰蛋白酶制备大豆肽正交实验的研究

采用固定化胰蛋白酶水解大豆蛋白,对大豆蛋白的最佳预处理温度进行了探讨,并对制备大豆肽的工艺条件进行了正交实验。结果表明:大豆蛋白的最佳预处理温度为90℃;固定化胰蛋白酶的表观米氏常数为12.5mg/mL。影响酶水解反应显著性的顺序为:温度,pH值,底物浓度,流速;在底物浓度2.7 mg/mL、温度60℃、pH8.7、流速0.6mL/min的条件下,利用固定化胰蛋白酶制备大豆肽,酶解液中的可溶性蛋白含量最大为1.414mg/mL,水解度41.51%。     

应用固定化胰蛋白酶制备大豆肽的研究

采用固定化胰蛋白酶水解大豆分离蛋白制备大豆低肽，对固定化胰蛋白酶水解工艺参数等进行了系统研究。结果表明：固定化胰蛋白酶的最适温度为60℃，最适pH为8．7，最佳底物浓度为2．0－3．0mg/mL，大豆分离蛋白的最佳流速为0．3mL/min，大豆分离蛋白的水解率达到45．6％，酶解液中大豆肽含量为1．462mg/mL。酶解液多肽分子量大部分在10000以下。     

木瓜蛋白酶制备大豆抗癌活性肽的条件优化

用木瓜蛋白酶对大豆分离蛋白进行酶解,制备大豆抗癌活性肽,并对其细胞生长抑制率、水解度和木瓜蛋白酶的最优作用条件进行研究。结果表明：在整个酶解过程中,大豆抗癌活性肽都具有明显的抗癌作用,但水解度与大豆抗癌活性肽的细胞生长抑制率之间不呈线性关系。底物质量浓度、酶用量、酶解温度、酶解时间和反应pH值都影响大豆抗癌活性肽的细胞生长抑制率。木瓜蛋白酶制备大豆抗癌活性肽的最优酶解条件为：底物大豆抗癌活性肽的浓度6g/100mL、酶用量7000U/g、酶解温度55℃、酶解时间4h、反应pH7.5,在此条件下得大豆抗癌活性肽细胞生长抑制率为28.13%。     

大豆蛋白改性酶解制备大豆肽的研究

利用大豆蛋白改性酶水解大豆分离蛋白制备大豆肽,以单因素试验和正交试验确定酶解最佳条件,通过高效液相法分析大豆肽的分子量分布,并检测了大豆肽的体外抗氧化效果。结果显示：在20g/L的底物浓度下的最佳条件为酶和底物比8 000U/g、温度55℃、pH值7.5、水解时间5h,水解度为51.4%。大豆肽主要为130～1 000u的短肽,占肽总量的86.3%。大豆肽对超氧阴离子（O2·^-）和羟自由基（.OH）的半最大清除浓度分别为1.3mg/mL和8.0mg/mL。表明大豆蛋白改性酶对大豆分离蛋白的水解能力较强,大豆肽有较强的抗氧化功能。     

木瓜蛋白酶与中性蛋白酶水解大豆分离蛋白的研究

研究了大豆分离蛋白经过加热预处理后用木瓜蛋白酶和中性蛋白酶水解的可行胜.以水解度(DH)为指标,考察了单因素水解条件得出:木瓜蛋白酶水解反应的最佳条件为反应底物浓度3.0%,pH 7.0,反应温度55℃,酶用量30μg/g;中性蛋白酶水解反应的最佳条件为反应底物浓度5.0%,pH 7.0,反应温度55℃,酶用量40 μg/g.在此条件下,大豆分离蛋白水解度分别为3.69%和9.80%.在一定条件下复合酶分步水解优于单一酶水解.     

罗汉果蛋白酶水解大豆蛋白研究

研究了采用罗汉果蛋白酶水解大豆分离蛋白制备大豆肽的水解工艺;分析了温度、pH、底物浓度、酶与底物比(质量百分比)和时间对酶水解的影响;得到了罗汉果蛋白酶水解大豆分离蛋白的最佳水解工艺为温度60℃、pH9.0、底物浓度5.0%、酶与底物比5.0%、水解时间1h。     

酶解制备高得率大豆肽工艺条件优化

用Alcalage碱性蛋白酶水解大豆分离蛋白制备大豆肽.通过单因素实验研究了底物质量分数、酶解pH、酶解温度、加酶量对蛋白水解度和大豆肽得率的影响,并通过响应面分析法对酶解条件进行了优化,得出最佳条件为:底物质量分数5%,酶解pH9.5,酶解温度55℃,加酶量5 400 U/g蛋白.在此条件下,大豆分离蛋白水解度为20.16%,大豆肽得率为92.30%.     

酶解荠蓝籽蛋白制备抗氧化肽工艺的优化

为制备荠蓝籽抗氧化肽,以荠蓝籽分离蛋白为原料,碱性蛋白酶Alcalase2.4L为水解酶,综合研究了酶解pH、温度、加酶量、底物浓度和时间等因素对荠蓝蛋白的水解度及产物还原能力的影响,并采用二次通用旋转组合设计实验优化水解条件。结果表明,制备荠蓝籽抗氧化肽的最佳酶解条件为:pH8.44,温度48.95℃,加酶量1198.96U/g蛋白,底物浓度1∶20,时间3.5h。该条件下的酶解产物具有较强的还原能力,酶解液浓度为2.997mg/mL,其还原能力与0.326mg/mL的Vc相当。      

木瓜蛋白酶水解大豆分离蛋白可行性的研究

文章研究了大豆分离蛋白经过加热预处理后用木瓜蛋白酶水解的可行性。以水解度(DH)为指标,考察了单因素及正交试验水解条件,得出结论:木瓜蛋白酶水解反应的最佳条件为反应底物浓度4.5%、pH 7.0、反应温度55℃、酶用量500Ug/g、反应时间2h;在上述条件下最终大豆蛋白水解度是6.28%。     

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