大麻纤维生物酶脱胶工艺试验

针对麻纤维采用化学脱胶会对纤维造成损伤的问题,提出了大麻纤维生物酶脱胶的新方法.并且用正交试验方法确定了生物酶脱胶的最佳工艺,即作用时间2h,果胶酶浓度5g/L,pH值4.5,温度50℃;后处理氢氧化钠浓度0.6%.生物酶对大麻进行脱胶处理,其作用条件温和,对纤维损伤小,生产中容易掌握脱胶的程度,有利于提高出麻率,且耗水少、污染轻.     

工业大麻纤维复合酶脱胶工艺研究

为响应绿色生态纺织品的号召,以低浓度碱液为预处理剂,采用果胶酶、木聚糖酶和漆酶的复合酶体系进行工业大麻纤维的脱胶,以脱胶后纤维的失重率和残胶率为指标,采用单因素试验和正交试验优化了复合酶工业大麻脱胶工艺,结果表明:工业大麻纤维碱预处理适宜的NaOH质量浓度为0.01g/mL,适宜预处理时间为20 min,复合酶脱胶体系适宜质量浓度为:果胶酶0.01 g/mL,木聚糖酶0.005 g/mL,漆酶0.002 g/mL,适宜pH值为4.2~5.0,脱胶后工业大麻纤维失重率和残胶率分别可达10.98%和4.82%,Fried评分为5分,纤维分离度较高。     

果胶酶在大麻纤维脱胶中的应用

针对麻纤维采用化学脱胶会对纤维造成损伤的问题,提出了大麻纤维果胶酶脱胶的新方法.用正交实验法确定了果胶酶脱胶的最佳工艺,即作用时间2 h,果胶酶用量5 g/L,pH值4.5,温度50 ℃;后处理氢氧化钠用量0.6%（对整理液质量）.生物酶对大麻进行脱胶处理,其作用条件温和,对纤维损伤小,生产中容易掌握脱胶的程度,有利于提高出麻率,且耗水少、污染轻.     

马蔺纤维果胶酶脱胶工艺研究

在分析马蔺叶化学成分基础上,通过化学预处理和生物酶相结合的方法对马蔺叶进行脱胶处理,提取马蔺纤维。测试并分析果胶酶NP浓度、脱胶温度、脱胶时间、p H值对脱胶效果的影响,并设计正交试验确定最佳脱胶工艺条件。且对提取的马蔺纤维的结构和基本性能进行测试。结果表明:最优脱胶工艺条件为果胶酶NP浓度为1.5 g/L,脱胶温度为50℃,脱胶时间为2 h,p H值为8;采用化学预处理和生物酶相结合的方法得到的马蔺纤维纵向外观成管状形体,有天然扭曲,纤维截面为扁圆形,有空腔;脱胶后纤维吸湿性较好。     

棉秆皮的生物脱胶工艺因素分析

针对传统化学蒸煮为主的棉秆皮脱胶方法提取棉秆皮纤维时易产生碱废水污染环境的缺点,采用生物脱胶工艺提取棉秆皮纤维。运用正交试验对棉秆皮的果胶酶脱胶工艺进行了优化,分析了果胶酶制剂的浓度、处理时间、温度、处理的pH值四个因素对生物脱胶的影响。对正交实验的结果进行分析后得出棉秆皮纤维脱胶优化工艺条件是酶制剂浓度12%(owf),温度40℃,时间30h,pH值4.4,浴比1∶30。在优化工艺条件下对棉秆皮纤维的性能进行了测试,结果表明其性能优良。     

酸性与碱性果胶酶固态亚麻纤维脱胶比较研究

以亚麻纤维残胶率和Fried评分为指标,比较研究了酸性与碱性果胶酶的固态亚麻脱胶效果,及添加EDTA对脱胶的影响。结果表明,在酶活力相同的条件下,碱性果胶酶能够在较短的脱胶时间内使亚麻纤维达到良好的分散程度,纤维残胶率较酸性果胶酶脱胶更低。添加EDTA对脱胶有促进作用,碱性条件下EDTA与果胶酶的协同作用更强,EDTA-酶的处理方法可在24 h使纤维分离程度达到良好(Fried为3分),残胶率为27.36%。     

大麻纤维高温-酶联合脱胶技术

为克服单一化学法脱胶对环境污染严重和单一的生物酶脱胶率低的缺点,研究了大麻纤维高温-酶联合脱胶技术,讨论了高温脱胶后3种不同酶处理的大麻纤维化学成分与断裂强度的变化,用SEM、FTIR对大麻纤维高温酶脱胶前后的表面形态结构、化学成分进行表征。实验结果表明:果胶酶可作为高温脱胶后大麻纤维的脱胶酶使用;高温-果胶酶脱胶后大麻纤维中的果胶和半纤维素、木质素含量分别下降了83.3%和79.2%。     

菠萝叶纤维酶法脱胶技术

为充分利用热带农业生物资源,弥补我国天然纺织原料的短缺,对菠萝叶纤维进行了酶法脱胶技术的理论探讨和试验研究。从自然界筛选高产果胶酶菌株,发酵生产出高活性果胶酶。研究结果表明:果胶酶用量8%,pH值7.0,温度52℃,处理4 h左右菠萝叶纤维能达到良好的脱胶效果。脱胶后菠萝叶纤维再经木聚糖酶处理45 min,再用30%的H2O2处理15 min能满足纺织工艺要求。     

菠萝叶纤维的脱胶工艺探讨

列举了菠萝叶纤维的两种脱胶方案，对比了两种脱胶方案的脱胶效果，优选了脱胶工艺配方，讨论了氢氧化钠浓度、煮练时间对脱胶效果的影响，并通过正交试验确定氢氧化钠浓度为4％，煮练时间为2．5h，采用化学松解。另外，介绍了超声波在菠萝叶纤维脱胶中的应用。     

苎麻的果胶酶/木聚糖酶复合生物酶脱胶

麻脱胶是麻纤维制品加工中的重要工序，试验以失重率、残胶率、白度、束纤维强度、液体芯吸高度等为评价指标，对比了果胶酶、木聚糖酶、果胶酶/木聚糖酶复合脱胶的应用效果。结果表明：热水/机械预处理、碱氧后处理对复合酶脱胶具有协同增效作用；相对于传统碱法脱胶，生物酶复合脱胶法不仅具有节能环保、作用条件温和的优势，同时能更好地保留苎麻固有特性，提高精干麻品质。     

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.