膜过滤技术在青梅酒澄清中的应用

采用不同微孔膜进行青梅酒过滤澄清试验,对比不同材料、不同孔径膜的过滤性能,研究不同膜与过滤方式对青梅酒主要理化指标、感官质量、澄清度与稳定性的影响,以此确定最佳滤膜与过滤方式。结果表明,错流过滤能使ULP143、USP143膜表现出良好的过滤性能,采用孔径0.1μm的USP143膜错流过滤青梅酒,感官质量、澄清度与稳定性显著提高,不影响理化指标,能保持酒体固有风格。生产上按此条件采用颇尔Oenoflow 2M过滤系统过滤5 k L青梅酒,流量维持2500~3000 L/h,滤液澄清有光泽,果香协调,口感清爽,风格突出,具有很好的稳定性,膜过滤技术在青梅酒生产中具有较高实用价值。     

超滤膜技术在L-阿拉伯糖发酵液精制中的应用

为研究超滤膜分离技术在L-阿拉伯糖发酵液精制提纯工艺中的应用,采用超滤膜系统对L-阿拉伯糖发酵液进行分离,从膜孔径、操作压力、操作温度、错流流速4个方面考察了发酵液对超滤膜通量的影响,以及不同过滤方式对后续离子交换树脂工作交换容量的影响。结果表明:选用孔径为1.0μm的超滤膜,控制操作压力0.4 MPa、操作温度50℃、错流流速6 m/s,其超滤膜对L-阿拉伯糖发酵液的平均膜通量为119.8 L/(m2·h)。采用热水(65℃)与化学清洗剂相结合的清洗方式,可使每次超滤膜的膜通量恢复至新膜通量的95%以上。超滤膜分离技术较之板框过滤可使后续离子交换树脂的工作交换容量提高51.45%,较之真空转鼓过滤可使后续离子交换树脂的工作交换容量提高68.02%。综上结果,超滤膜分离技术可以高效地截留L-阿拉伯糖发酵液中的酵母、菌体、胶质、蛋白及色素等杂质,使后续的离子交换工序顺利进行,从而提高L-阿拉伯糖的产品品质。     

甘蔗混合汁粒径分布及陶瓷微滤膜过滤阻力研究

建立了甘蔗混合汁中颗粒粒径分布测定和分析方法;研究了0．1μm、0．2μm和0．45μm陶瓷微滤膜分析甘蔗混合汁时的阻力分布,探讨了不同膜元件主要阻力形式,确定了阻力分析方法。结果表明：致密性膜的制造精度越高,过滤料液时总阻力相对较小,孔隙率高的膜元件堵塞阻力随膜孔径减小而降低,利于膜通量的恢复和延长使用时间。     

陶瓷膜处理乙醇发酵废水的工艺条件研究

发酵法生产乙醇的过程中产生大量废水,文中采用陶瓷膜处理乙醇发酵废水,考察了膜孔径、料液性质以及操作条件对过滤过程的影响。结果表明,陶瓷膜过滤乙醇发酵废水有较好的效果,化学需氧量(COD)去除率达80%,固体悬浮物(SS)截留率在99%以上。确定了孔径为200nm的膜管在pH值为8.0,错流速度为5m/s,温度为50℃,操作压力0.15MPa条件下操作,膜通量大于700L/(m2·h)。     

陶瓷膜技术在黄酒生产中的应用

采用错流过滤技术，用陶瓷膜超滤装置对黄酒进行过滤，探讨了超滤时间、压力、温度对膜通量的影响，考查了相关质量指标的变化规律。结果表明，在温度为20℃-25℃、压力为0．2MPa-0．25MPa时，用孔径为0．15μm膜过滤黄酒，其中高分子蛋白质的去除率为56．9％，黄酒的非生物稳定性显著提高，并保持了黄酒的传统风味，且理化指标符合要求。     

陶瓷微滤膜过滤生酱油的污染阻力研究

在系列阻力模型的基础上,系统考察了用陶瓷微滤膜过滤生酱油的过程中操作条件、环境和膜结构等对各部分污染阻力的影响.结果表明:Rt和Rcp随孔径增加而增大,而Rc和Rif,却有稍稍减小的趋势;ZrO2的Rt远远大于a-Al2O2的;ZrO2膜的污染阻力中Rcp是主导部分,而a-Al2O3膜的Rc和Rcp共同主导微滤过程的污染阻力;由于Rcp的作用,0.2μm a-Al2O3膜的渗透通量迅速下降,Rcp是主导的污染阻力;最后给出了不同的污染阻力与操作条件的纯经验函数关系.     

过滤时间对空气过滤材料过滤性能的影响

通过设定不同的过滤时间,测试静电纺纳米纤维膜和熔喷非织造材料的过滤性能,研究其过滤效率和过滤阻力随过滤时间的变化规律。结果发现:过滤时间的增加使得过滤效率和过滤阻力呈现不同程度的增长。过滤时间的增加对静电纺纳米纤维膜过滤性能的影响较显著,设计面密度为10.00 g/m~2的静电纺纳米纤维膜的过滤效率和过滤阻力明显上升,而设计面密度为20.00和40.00 g/m~2的静电纺纳米纤维膜因孔径过小导致其过滤阻力在短时间内超过1 000 Pa,故面密度较大的静电纺纳米纤维膜不适合用于普通的空气过滤。熔喷非织造材料结构较蓬松,孔径较大,孔隙不易被堵塞,当过滤时间为12 h时,除设计面密度为40.00 g/m~2的熔喷非织造材料过滤阻力增加较明显外,其他熔喷非织造材料的过滤效率和过滤阻力增幅均不大。     

造纸过程水对聚醚酮超滤膜污染机理的初步研究

对聚醚酮超滤膜污染的机理进行初步研究,研究表明:在优化的操作条件下过滤初期,PEK-20000膜超滤过程既符合堵塞过滤规律又符合沉积过滤规律,90min后膜面沉积阻力大于内部污染阻力。     

无机陶瓷膜澄清酱油的工艺研究

研究了不同孔径的无机陶瓷膜处理酱油，膜通量与过滤温度、过滤时间、操作压力及流速的关系，确定选用200nm的陶瓷膜、操作温度在30℃左右、操作压力为0．20 MPa过滤酱油可以解决酱油的二次沉淀现象，并可获得较高的膜通量。     

啤酒错流过滤技术综合分析

错流过滤是全面推动啤酒过滤技术革新的新型技术.通过过滤过程的分析,建立了工艺优化的思路和解决膜堵塞问题的方法,评价了该技术成熟后的经济效益,及啤酒错流过滤技术在啤酒业可观的发展前景.     

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.     

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.     

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.     

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.     

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.     

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.     

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.