酪蛋白糖巨肽超滤分离的工艺优化研究

目的:研究超滤分离酪蛋白糖巨肽的最优工艺参数,以达到最佳超滤通量性能。方法:采用超滤方法分离乳清浓缩蛋白(WPC80)中的酪蛋白糖巨肽,研究料液pH值、操作压力和温度等对膜渗透通量的影响。利用SDS-PAGE凝胶电泳技术分析超滤截留液的相对分子量分布。结果:实验表明溶液pH7.0、操作压力0.3MPa、温度45℃时膜渗透通量最高,超滤酪蛋白糖巨肽的截留率达到97.54%,产物纯度达到92.45%,经SDS-PAGE凝胶电泳测定,酪蛋白糖巨肽的平均分子量68.86%为30.47ku,31.14%为19.22ku。结论:超滤技术是将酪蛋白糖巨肽与其他乳清蛋白分离的有效方法。     

陶瓷膜超滤技术浓缩乳清的工艺参数研究

采用孔径为20nm的无机陶瓷膜超滤干酪副产物乳清,浓缩乳清蛋白。通过对膜过滤压力、温度以及乳清pH三个因素进行单因素分析以及正交实验优化,得到最佳工艺条件:操作压力0.25MPa,温度51℃,pH6.1,此条件下超滤膜渗透通量达到169.37L/m2.h,乳清蛋白可浓缩至5.4%,经喷雾干燥制得WPC蛋白质含量为38.2%。     

陶瓷膜超滤技术浓缩乳清的工艺参数研究

采用孔径为20nm的无机陶瓷膜超滤干酪副产物乳清,浓缩乳清蛋白。通过对膜过滤压力、温度以及乳清pH三个因素进行单因素分析以及正交实验优化,得到最佳工艺条件:操作压力0.25MPa,温度51℃,pH6.1,此条件下超滤膜渗透通量达到169.37L/m2.h,乳清蛋白可浓缩至5.4%,经喷雾干燥制得WPC蛋白质含量为38.2%。      

大豆乳清中β-淀粉酶的超滤提取技术研究

大豆乳清废水中含有丰富的β-淀粉酶。通过超滤技术对乳清废水中的β-淀粉酶进行浓缩回收,研究了膜截留分子量（MWCO）、操作温度、料液pH对超滤效果的影响。结果表明,选用MWCO3ku的膜,在跨膜压差2bar、温度（25±3）℃、pH7的操作条件下,膜通量由初始的44L/（m2·h）衰减至23L/（m2·h）,平均通量达到35L/（m2·h）;β-淀粉酶的酶活力可达到101U/mL,料液的浓缩倍数为10倍,酶活浓缩倍数约为9倍,总酶活的回收率为92%,浓缩液较高的β-淀粉酶酶活力为下一阶段的分离纯化奠定了基础,为大豆深加工废水综合利用提供了依据。      

正交试验优化银条多糖超滤浓缩工艺

以膜通量为指标,首先探讨操作压力、超滤温度和料液pH值3个工艺参数对超滤浓缩银条多糖的影响,在此基础上通过正交试验确定超滤浓缩的最佳工艺参数,最后通过测定清洗前后膜的水通量变化确定最佳的超滤膜清洗方法。结果表明超滤浓缩效果优于常规浓缩的效果,超滤浓缩银条多糖的最佳工艺参数为操作压力0.35MPa、操作温度30℃、料液pH6.5;最佳膜清洗方法为用40℃、pH8.5的NaOH溶液清洗0.5h,此时清洗前后纯水的膜通量相差9.00L/(m2.h)。     

乳清蛋白超滤过程中膜污染机制及监测方法研究进展

尽管乳清蛋白超滤浓缩已经实现工业化应用,但仍存在膜污染严重、生产成本高等问题。该文从pH、温度、跨膜压力、离子强度等方面综述乳清蛋白超滤过程中膜污染的形成机制;介绍了目前描述乳清蛋白超滤过程中膜污染的3种数学模型,用于预测膜污染过程中膜通量随时间变化规律;总结了乳清蛋白超滤过程中的原位监测技术的物理原理、优点和缺点,以预测和控制超滤过程中的膜污染行为,为蛋白超滤过程的实时监测提供有效的动态信息,为膜污染的控制提供理论依据。     

超滤浓缩微生物胞外多糖PS-9415发酵液的研究

本文采用了截留分子量为70，000的平板超滤膜对微生物胞外多糖PS－9415的发酵液进行了超滤浓缩的研究。膜的透过通量受料液浓度，搅拌速度，操作压力等因素的影响。其中，降低料液浓度，增加搅拌，提高压差可以增加膜的透过通量。0．5％的多糖在室温,0.15MPa下超滤108min可浓缩2倍。     

中空纤维超滤膜浓缩胞外多糖PS-9415发酵液的研究

采用了截留分子量为50,000的内压式中空纤维超滤器对微生物胞外多糖PS-9415发酵液进行浓缩分离的研究。研究表明,膜的透过通量受温度、料液浓度、操作压力等操作参数的影响,其中高温、低浓度的料液在较高的操作压力下有较高的透过通量。经过稀释、离心除菌的发酵液比不经过处理的发酵液透过通量高,衰减慢。0.05MPa下对3%的料液3L超滤浓缩,可得到5.8%的浓缩液,多糖回收率为82.7%;0.1MPa下0.5%的料液可浓缩至2.95%,浓度提高了4.9倍。      

中空纤维超滤膜浓缩胞外多糖PS-9415发酵液的研究

采用了截留分子量为50,000的内压式中空纤维超滤器对微生物胞外多糖PS-9415发酵液进行浓缩分离的研究。研究表明,膜的透过通量受温度、料液浓度、操作压力等操作参数的影响,其中高温、低浓度的料液在较高的操作压力下有较高的透过通量。经过稀释、离心除菌的发酵液比不经过处理的发酵液透过通量高,衰减慢。0.05MPa下对3%的料液3L超滤浓缩,可得到5.8%的浓缩液,多糖回收率为82.7%;0.1MPa下0.5%的料液可浓缩至2.95%,浓度提高了4.9倍。     

酶聚合结合超滤技术分离豆腐废水乳清蛋白的工艺研究

为改善豆腐乳清蛋白及低聚糖的回收率、提高膜通量,研究采用转谷氨酰胺酶在豆腐黄浆水自然条件下(温度50℃、pH值6.0)对乳清原液预处理,使蛋白质聚合,方便后续分离工艺选用截留分子量大的超滤膜分离大豆乳清蛋白。数据显示转谷氨酰胺酶Ⅰ可有效催化大豆乳清蛋白聚合,1%的酶添加量50℃反应30min即可催化95%以上的大豆乳清蛋白聚合,酶添加量3‰,聚合时间延长至5h。与对照组相比,乳清采用酶法预处理然后超滤分离,蛋白截留率及膜通量分别提高了2倍和1.3倍,而低聚糖的透过率没有明显影响。试验结果表明,相对于单纯的超滤工艺酶聚合预处理乳清然后超滤的分离效果是显著的。     

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