卷式膜超滤L-乳酸发酵液过程研究

比较截留分子量(MWCO)为1000D 和3000D 的卷式超滤膜在去除L- 乳酸发酵液中蛋白质等杂质过程中对蛋白质截留率和乳酸透过率的影响,研究超滤时间、操作压力、蛋白质质量浓度及操作温度等操作工艺参数对膜通量的影响,分析膜通量随时间的变化规律,建立描述膜通量与操作压力、蛋白质浓度关系的数学模型。结果表明：MWCO 为3000D 的膜更适合用于超滤L- 乳酸发酵液,其膜通量随着超滤时间的延长衰减;随着操作压力和温度的增加而升高,随着蛋白质质量浓度的增加而降低,所建立的数学模型与实验结果吻合良好。     

超滤法提取发酵液中核黄素

采用截留分子质量(MWCO)为1000 Da、10 kDa和30 kDa的卷式膜,探索卷式膜超滤核黄素发酵液的可行性。对比分析超滤膜的杂质截留率和膜通量,发现MWCO为10 kDa的卷式超滤膜对核黄素具有较好的分离效果。通过研究操作压力、温度、流速及浓缩倍数对膜通量的影响,确定核黄素发酵液超滤的最佳条件为:温度30℃,流速5 m/s,操作压力0.2 MPa,浓缩倍数为3.8倍。超滤后,经过氧化结晶核黄素的纯度可达98.6%,总回收率达95%。     

酵母溶液超滤渗滤分离研究

采用MWCO为5000的超滤膜对酵母溶液进行超滤渗滤研究。结果表明，超滤通量随操作压力和温度的升高而增大，且在较高操作压力下的通量衰减较快，推导出超滤通量和料液溶质浓度的对数呈线性关系，可以对超滤通量变化情况作较好预测；随超滤和渗滤的进行，浓缩液中蛋白质主体浓度逐渐升高至20mg／mL，而超滤液和渗滤波中蛋白质最终浓度仅为0．3mg／mL，蛋白质被去除率达90％以上；浓缩液和渗滤液中海藻糖浓度几乎相同，最终浓度下降到0．9mg／mL左右，总回收率达到80％以上。     

酵母抽提物提取海藻糖超滤特性研究

采用聚醚砜超滤膜对酵母味素溶液进行超滤试验，并对超滤特性及影响特性的操作因素进行研究，结果表明：在整个超滤过程，通量衰减变化很大，蛋白质主体浓度的对数和渗透通量呈线性关系；随料液浓度增加，膜通量下降，蛋白截留率和海藻糖透过率增加；料液pH和操作压力均影响通量、蛋白截留率和海藻糖透过率。经提取后的海藻糖浓度为25．7％，整个过程海藻糖总提取率达89．8％。     

膜分离技术提取海藻糖的工艺

采用超滤、纳滤操作对酵母抽提物进行处理，结果表明：操作压力、操作时间及料液体积流量对超滤有很大影响，所选MWCO为5000的膜件可去除96％以上的大分子蛋白质，起到纳滤预处理作用．采用MWCO为300的纳滤膜对超滤液进行浓缩纯化，海藻糖总提取率高达85．6％，大大高于传统方法．操作条件如进料压力、浓缩倍数及操作方式对纳滤过程均有很大影响。     

卷式膜超滤浓缩猪血浆工艺研究

以猪血浆液为研究对象,比较截留分子量（MWCO）为20000D、10000D和5000D的卷式超滤膜对血浆浓缩效果的影响,研究超滤血浆过程中,超滤压力、超滤温度、血浆蛋白浓度、pH值和时间对超滤膜效果的影响。结果表明,MWCO=5000D膜更适合用于超滤浓缩血浆液,超滤压力和蛋白浓度对通量影响更加显著。综合考虑猪血浆蛋白加工实际情况,获得最佳工艺条件为：在1．5MPa压力下,将分离血浆液（pH值7．0—7．5、蛋白浓度7．5％～8．0％、温度13～15℃）,连续超滤40min。     

酸性染料废水纳滤处理的影响因素研究

为探讨酸性染料废水纳滤分离过程的影响因素、截留率和膜通量变化规律,选取常见的酸性大红染料,对染料模拟废水进行纳滤分离研究.结果表明:随操作压力的升高,染料截留率降低,盐截留率先升后降,膜通量增大;随着染料质量浓度的增加,膜通量降低,而染料截留率、盐截留率逐渐增加;pH=5~7时,染料的截留率达到最大,盐的截留率和膜通量呈下降趋势;染料的截留率、盐的截留率和膜通量随盐质量浓度的升高而降低;随运行时间的延长,膜通量先增加然后趋于稳定,染料和盐的截留率均有所下降.     

膜分离在蛋白质分离纯化中的应用

以压力差为推动力膜分离过程（过滤，超滤，纳滤，反渗透）的分离性能由透过通量和截留率表征，其操作模式分浓缩和渗滤两种。膜分离技术用于分离，纯化，回收和浓缩蛋白质，如乳清蛋白，血清白蛋白，蛋清蛋白，西蒙德木蛋白，重组白细胞介素－2包涵体以及二元蛋白质混合物等。     

膜集成工艺浓缩灵芝水提液的研究

高效节能的膜集成技术已开始应用于食品和药用植物中有效成分的分离提取。文中针对灵芝提取液的特性,依据微孔过滤(MF)、超滤(UF)、纳滤(NF)各种膜对特定物质的选择分离性能,设计了新型膜集成工艺,即筛网和滤纸粗过滤除杂和MF净化处理,进而用不同切割分子质量(MWCO)膜进行两级UF、最后用NF净化浓缩灵芝水提液的创新技术。在操作压力≤0.20 MPa和15 m/s的高膜面流速,1.0 mL/(cm~2·h)恒通量模式下,灵芝水提液先后经MWCO分别为5万的聚丙烯腈(PAN)膜和1万的醋酸纤维素(CA)膜进行UF批次处理。UF渗透液再经截留分子质量为1 50～300的DK(标准)型聚酰胺(PA)膜进行纳滤浓缩,浓缩倍数达6倍时,渗透通量在0.92～0.33 mL/(cm~2·h),纳滤渗透液的色度在浓缩过程稳定在70～80,有效成分截留率高。     

中试超滤系统浓缩分离南瓜多糖

为进一步推动南瓜作物的深加工及高附加值生产,采用自行研制的全自动超滤浓缩中试系统对南瓜多糖溶液进行超滤浓缩,分别考察超滤温度、超滤时间、超滤压力及进料液浓度对超滤膜通量的影响,发现膜通量随温度和压力的增加而增大,随超滤时间和料液浓度的增加而减小。对超滤膜的污染情况也进行研究,发现随膜使用时间的延长,超滤过程将造成难以恢复的膜污染。     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.