枯草芽孢杆菌发酵制备玉米肽－葡萄糖螯合物的条件优化

以玉米肽和葡萄糖为底物,利用枯草芽孢杆菌(Bacillus subtilis)ls-45为菌种发酵,以DPPH清除率为指标,通过单因素及响应面实验优化枯草芽孢杆菌发酵制备玉米肽-葡萄糖螯合物的条件,为研究玉米肽-葡萄糖螯合物体内、体外抗氧化等功能实验提供数据支撑。采用四因素三水平响应面实验确定最佳接种量、pH值、发酵温度及发酵时间。结果表明:利用枯草芽孢杆菌发酵制备玉米肽-葡萄糖螯合物的最佳工艺条件为接种量10%,发酵时间46 h,pH 6,发酵温度37℃,此时DPPH清除率为90.82%。     

牛蒡多糖锌的制备工艺优化及其抗氧化活性评价

本研究以牛蒡多糖和硫酸锌为原料,通过硫酸锌法合成牛蒡多糖锌。采用单因素实验和响应面试验优化牛蒡多糖锌的制备工艺,并对其抗氧化活性进行研究。结果表明：牛蒡多糖锌的最佳制备工艺为：牛蒡多糖与硫酸锌的质量比为37:1、温度50℃、时间121 min、pH8.6,此时螯合率为93.21%±0.58%。抗氧化试验表明：当浓度为1.0 mg/mL时,牛蒡多糖锌对DPPH自由基、超氧阴离子自由基和ABTS+自由基的清除率分别为84.59%±0.60%、67.27%±1.00%、38.88%±1.68%,自由基清除能力均优于牛蒡多糖;而牛蒡多糖锌对羟基自由基的清除率略低于牛蒡多糖。锌修饰牛蒡多糖可增强牛蒡多糖的抗氧化能力,为牛蒡多糖的高值化利用提供了参考。     

松仁肽的制备及抗氧化活性研究

以松子分离蛋白为原料,水解度为评价指标,通过单因素和响应面法优化松仁肽的酶解工艺,并以羟自由基清除能力和DPPH清除率评价松仁肽的抗氧化活性。试验结果表明,松仁肽制备的最佳工艺条件为酶解温度52℃、底物浓度3.2%,pH 9.1,酶解时间3 h、加酶量9 000 U/g。在此酶解条件下,水解度可达0.329 7。制备的松仁肽在浓度24 mg/mL时能清除全部羟自由基;在10 mg/mL时对DPPH的清除率达到75%。此时的松仁肽表现出一定的抗氧化活性。     

响应面法优化鱼皮胶原蛋白多肽螯合锌工艺

采用响应面法优化鱼皮胶原蛋白多肽与硫酸锌进行螯合反应的条件,制备胶原肽螯合锌产品.以胶原肽与硫酸锌的质量比、时间、温度和pH值4因素3水平进行Box-Behnken中心组合实验,运用Design-Expert7.0数据统计分析软件,建立螯合率的回归方程.结果表明,最佳螯合工艺条件为胶原肽与硫酸锌的质量比2.8∶1,时间33.2min,温度40.1℃,pH值7.3.在此条件下,螯合率为67.25％,与模型的预测值67.36％接近.紫外光谱检测结果初步显示,胶原肽与锌发生了螯合并产生了一种新型螯合物.     

酪蛋白GYLEQ抗氧化肽——钙螯合物的制备、表征及功能特性

目的:开发具有抗氧化活性和补钙功能的产品。方法:在固相法合成GYLEQ抗氧化肽的基础上,采用单因素和正交试验优化酪蛋白GYLEQ抗氧化肽与钙离子螯合反应条件,利用红外光谱和扫描电镜表征GYLEQ-Ca螯合物的结构,并分析GYLEQ-Ca螯合物体外抗氧化活性、模拟胃肠液中的持钙率以及对细胞活力的影响。结果:GYLEQ-Ca螯合反应最佳条件为螯合温度50℃,螯合时间40 min, pH 7.5,肽钙质量比4∶1,其中温度对螯合率的影响达到了极显著水平,pH和肽—钙质量比对螯合率的影响达到了显著水平。螯合后产物的红外波谱吸收峰与GYLEQ肽相比发生了改变,扫描电镜观察发现GYLEQ肽为颗粒状,而GYLEQ-Ca螯合物为黏连在一起的网状结构,表明GYLEQ肽与钙离子反应生成了新的化合物。GYLEQ-Ca螯合物的DPPH自由基、羟自由基清除率和还原力高于GYLEQ肽,GYLEQ-Ca螯合物在模拟肠液中持钙率维持在70%以上,且无细胞毒性。结论:GYLEQ-Ca螯合物具有较好的抗氧化活性和钙维持率。     

蚕蛹源肽锌纳米粒子的制备及其结构表征

为开发安全易吸收的补锌制剂,提升蚕蛹的利用价值,通过酶解蚕蛹蛋白制备蚕蛹肽,并将其与锌螯合生成肽锌螯合物。以锌螯合能力为指标,确定蚕蛹肽的酶解制备工艺及蚕蛹肽锌螯合物的制备工艺,采用紫外光谱、荧光光谱、扫描电镜、元素分析仪、粒径分析及红外光谱等技术对螯合前后的样品进行结构表征。结果表明,酶解制备蚕蛹肽的条件为碱性蛋白酶加酶量为1%、pH8.0、温度50℃、酶解时间6 h,该条件下的螯合率达58.05%;肽锌纳米粒的最佳制备条件为肽锌质量比1:0.5、pH6.5,温度55℃,时间20 min,此时螯合率达72.63%;添加硫酸锌后,紫外光谱与荧光光谱强度的减弱显示Zn²⁺与蚕蛹肽成功的发生了结合,所得蚕蛹肽-锌螯合物为粒径71.99 nm的纳米粒子,表面呈均匀的颗粒状结构,锌相对含量达37.46%,肽链中的-COOH、-NH₂和-C=O是锌离子与蚕蛹肽的主要结合位点。综上,蚕蛹是制备肽锌螯合物的良好原材料,这为丰富有机锌补充剂资源库和蚕蛹综合利用奠定了一定的理论基础。     

牡蛎肽锌螯合物的制备工艺研究

分析牡蛎肽氨基酸组成及相对分子质量分布,并以牡蛎肽为原料、硫酸锌为锌源对牡蛎肽锌螯合物的制备工艺进行研究,通过测定锌离子螯合率和螯合物得率衡量螯合效果。结果表明,牡蛎肽相对分子质量小于1000 u的组分高达92.34%,富含谷氨酸和天冬氨酸这两种酸性氨基酸及其酰胺;保证螯合率及得率的最佳螯合条件为:肽与硫酸锌质量比为20∶1,肽浓度为0.06 g/m L,反应温度为50℃,沉淀剂乙醇为5倍反应液体积,p H5.33,反应时间60 min。在此条件下锌离子的螯合率为89.55%±0.23%,螯合物得率为56.64%±0.55%。      

牡蛎肽锌螯合物的制备工艺研究

分析牡蛎肽氨基酸组成及相对分子质量分布,并以牡蛎肽为原料、硫酸锌为锌源对牡蛎肽锌螯合物的制备工艺进行研究,通过测定锌离子螯合率和螯合物得率衡量螯合效果。结果表明,牡蛎肽相对分子质量小于1000 u的组分高达92.34%,富含谷氨酸和天冬氨酸这两种酸性氨基酸及其酰胺;保证螯合率及得率的最佳螯合条件为:肽与硫酸锌质量比为20∶1,肽浓度为0.06 g/m L,反应温度为50℃,沉淀剂乙醇为5倍反应液体积,p H5.33,反应时间60 min。在此条件下锌离子的螯合率为89.55%±0.23%,螯合物得率为56.64%±0.55%。     

正交试验优化花生肽螯合锌的制备工艺

研究了花生蛋白水解物和锌离子制备肽锌螯合物的工艺条件,以螯合率为评价指标,考察肽与锌的质量比、反应pH、反应温度和反应时间对螯合反应的影响。在单因素试验基础上,采用4因素3水平正交法确定花生肽-锌螯合物的制备工艺。最佳工艺条件:花生肽-锌质量比4∶1、反应体系pH 6.0、反应温度50℃、反应时间40 min。在此条件下,锌的螯合率为57.04%。     

富锌小麦蛋白水解物制备技术及其理化性质研究

为研究锌-肽螯合物的制备方法,并对其理化性质进行初步探讨,以小麦蛋白(wheat protein,WP)和硫酸锌为原料,对富锌小麦蛋白水解物制备工艺进行优化,并采用光谱分析初步探明螯合位点,考察富锌小麦蛋白水解物的基本理化性质.结果表明,富锌小麦蛋白水解物的最佳螯合工艺条件为锌与蛋白质量比1.7:1、螯合温度65℃、螯...     

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