光叶楮白皮生物法脱胶

对影响光叶楮白皮生物法制浆的主要外界因素进行了探讨.结果表明,生物法制浆最佳工艺条件为初始pH7,温度30℃,液比115～125,菌液接种量3%;加入助剂能够显著提高成浆效果,且以1.5%～2.5%的尿素为最佳.最优化条件下的实验结果为得率70.02%,高锰酸钾值14.56,白度43.2%ISO,成浆时间94h,废液pH值4.05,吨浆产生CODCr为0.337t.     

微生物发酵韧皮纤维制浆造纸的研究

利用亨氏厌氧技术从沤麻塘底泥等厌氧生境中分离筛选到clostridium属的N_2,Y_4,Z_(2-8)三株厌氧细菌,研究结果表明,其户酶最适pH为70—7.4,最适温度为30℃,最佳碳源为淀粉,最佳氮源为豆饼粉。N_2、Y_4、Z_(2-8)的果胶酶活分别为:913u,973u,927u,半纤维素酶活分别为:137u、140u、170u,纤维素酶活分别为0、3u、0,产酶高峰时间在72小时左右。 三个菌株混合发酵红麻皮、构皮等韧皮纤维,5天可成浆。打浆后做手抄片,红麻皮浆手抄片白度为40.5,裂断长为3529m。构皮浆手抄片白度为22.7,裂断长为2998m。     

光叶楮白皮生物脱胶制浆及其机理研究

对影响光叶楮白皮生物脱胶制浆的主要因素及脱胶酶特性进行了研究。结果表明，生物脱胶制浆的最优工艺条件为：初始pH值7，温度30℃，液比1：15～1：25，接种量3％；加入氨源助剂能够显著提高成浆效果，且以用量为1．5％。2．5％的尿素为佳。最优条件下的制浆结果为：得率70．O％，高锰酸钾值14，6，白度43，2％ISO，成浆时间94h，废液pH值4．0，CODc。值为O．337L／t浆。脱胶酶活力分析结果表明：发酵初期，酶活力都随时间延长而升高，发酵至36h，果胶酶活力达到峰值，木聚糖酶活力在发酵至60h达到峰值，峰值过后，2种酶的活力随时间延长逐渐降低，纤维素酶活力在整个周期内缓慢增加，没有峰值出现。     

脂肪酶产生菌NJY-1-7的选育及发酵条件的研究

从云南省福贡县的玉米地土壤样品中筛选到一株耐高温产碱性脂肪酶的菌株NJY-1-7,通过16SrDNA鉴定该菌株为伯克氏菌(Burkholderia cenocepacia)。对其发酵条件进行研究结果表明:该菌株产酶的最适培养时间为48h,酶促反应的最适作用pH值为9.0,最适作用温度为50℃,摇瓶发酵最适产酶条件为橄榄油1%,MgSO4.7H2O 0.05%,可溶性淀粉0.3%,酵母膏0.5%,单蒸水70mL。在此条件下发酵脂肪酶酶活力为42.00U/mL。     

高产酸乳酸菌的筛选、鉴定和生长特性研究

为了获得高品质的乳酸菌用于工业生产,从本实验室保存的8株乳酸菌中筛选出3株产酸量高、生长良好的乳酸菌,并对筛选出的三株菌进行了分析鉴定和生长特性研究.结果表明,鉴定的3株菌中,菌ST1和菌ST3均为副干酪乳杆菌,菌ST6为鼠李糖乳杆菌 . 菌株ST1和ST3的最适生长温度为31～37℃,ST6的最适生长温度为37～43℃.菌株ST1的最适初始pH为5～7,菌株ST3和ST6的最适初始pH均为6～7 . 盐度＞14％会对菌株的生长产生明显抑制.     

光叶楮白皮碱性过氧化氢草酸盐法制浆工艺条件的优化

讨论了影响光叶楮白皮制浆的各种因素,筛选出APO(碱性过氧化氢草酸盐)法制浆的最佳工艺条件为:H2O2用量9%,Na2C2O4用量20%,NaOH用量9%,AQ用量0.10%,EDTA用量0.20%,液比1∶9,最高温度85℃,保温时间3 h。在此条件下制浆,所得浆料得率63.5%,高锰酸钾值7.6,白度69.7%ISO。     

光叶楮白皮酸提取果胶及碱性过氧化氢制浆

优化了用盐酸提取光叶楮白皮果胶的最佳工艺条件:萃取液比1∶20,萃取pH值1.5,萃取时间2.0h,萃取温度90℃,此时果胶得率为3.96%;碱性H2O2处理的优化工艺条件为:H2O2用量1%,NaOH用量3%,液比1∶6,温度80℃,时间30min。此时细浆得率为47.0%,白度为61.3%。     

光叶楮白皮生物制浆及漂白废水的特性及处理

光叶楮白皮生物制浆及漂白所产生的废水总量为每吨漂白浆145.5 m3。制浆与漂白段的废水的BOD/COD(B/C)分别为0.38和0.24,可以用生物法处理。用SBR法处理时的最优曝气时间为8 h;最佳初始pH值:制浆混合废水为7.5,漂白混合废水为7.0;处理结果:制浆混合废水CODC r去除率为84.2%,BOD5去除率达到89.6%;漂白混合废水CODC r去除率为78.1%,BOD5去除率达到80.9%。     

耐高温α-淀粉酶产生菌的选育研究

从土壤中分离到1株能在55℃生长并分泌耐高温α-淀粉酶的菌株,其最适生长pH值为7．0-8．0,最适生长温度50℃。该菌株经初步鉴定为芽孢杆菌,疑似微地衣芽孢杆菌,命名为DG-1。对该菌株分泌的耐高温α-淀粉酶的性质研究表明,最适作用pH值为7．0,在pH6．0-7．5的范围内有较高酶活。最适反应温度为95℃,95℃保温60min处理后酶活仅损失4．73％。经紫外线诱变处理,得到菌株DG-4,酶活较出发菌株提高了104．6％。     

用于壳聚糖降解的复合酶制剂产生菌的筛选

以壳聚糖为唯一碳源,结合固态培养基发酵培养,从自然界中筛选得到一株产复合酶的菌株,初步鉴定为曲霉属.该菌产复合酶中以壳聚糖酶、纤维素酶和α-淀粉酶为主,它们的酶活分别为2.206、0.790、3.229U/mL.该复合酶降解壳聚糖的最适温度为50℃,最适pH为5.6,最适时间为4h.通过有机溶剂分级沉淀,发现该复合酶降解壳聚糖的最终产物以聚合度为8～16的壳寡糖为主,表明该复合酶在壳寡糖制备方面具有一定的应用价值.     

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.