酶对荔枝液化效果的研究

研究了纤维素酶、半纤维素酶、果胶酶对荔枝果肉的液化效果。通过试验发现果胶酶、纤维素酶单一使用时的液化效果较好。果胶酶在用量为1%时可达到33%的汁液得率。纤维素酶在用量为0.9%时可得到25%的汁液得率。半纤维素酶在用量低时汁液得率较低,但在用量为0.8%以上时可达到与纤维素酶同样的汁液得率。纤维素酶、半纤维素酶、果胶酶几种酶复合使用时,以半纤维素酶用量为0.6%、纤维素酶用量为0.4%、果胶酶用量为1.0%时的液化效果最佳。     

白蚁肠腔内纤维素酶概述及在食品发酵中的应用

白蚁纤维素酶的研究与开发已成为近年来的热点.本研究从白蚁肠腔纤维素酶的来源、国内外白蚁纤维素酶的研究状况、白蚁降解木质纤维素的机理及纤维素酶在发酵食品中的应用等方面综述了白蚁纤维素酶的研究现状.     

酶法液化制取龙眼汁的研究

研究了利用纤维素酶、半纤维素酶、果胶酶单一使用和复合使用时,对龙眼进行全果液化取汁的工艺效果以及有关工艺条件。研究发现单一使用纤维素酶、半纤维素酶、果胶酶对龙眼进行全果液化时,果汁产率在酶用量为0.6%之前随酶用量的增加增幅较大,在酶用量为0.6%之后随酶用量的增加增幅较小。同时还发现纤维素酶、半纤维素酶对龙眼的液化效果较好,果胶酶对龙眼液化效果则很差。通过正交试验结果表明,纤维素酶、半纤维素酶、果胶酶复合使用时,以半纤维素酶用量为0.6%,果胶酶用量为0.9%,纤维素酶用量为0.6%时,液化效果最佳。     

纤维素酶高产菌株选育研究进展

本文综述了纤维素酶的类别及产纤维素酶的微生物菌种,不同菌株通过各种方法诱变选育,可提高产纤维素酶的能力,旨在为更好地利用产纤维素酶高的菌株提供参考。     

旧报纸纤维素酶/半纤维素酶与漆酶协同脱墨工艺

对旧报纸纤维素酶/半纤维素酶和漆酶协同脱墨进行了研究.实验结果表明,使用纤维素酶与漆酶进行脱墨,脱墨浆漂白后白度较单独使用纤维素酶和漆酶分别提高了2.4%ISO和3.8%ISO,裂断长较单独使用纤维素酶提高了约30%;使用半纤维素酶与漆酶进行脱墨,脱墨浆漂白后白度比单独使用半纤维素酶和漆酶分别提高了2.7%ISO和8.3%ISO,裂断长较单独使用半纤维素酶提高了20%.     

木耳菌糠中纤维素酶的提取与活性研究

通过盐析法从木耳菌糠中提取粗纤维素酶,并对其活性和溶解性进行研究测定,然后与相应的标准纤维素酶进行比较。结果表明,每公斤干重的木耳菌糠可提取粗纤维素酶11.39克,粗纤维素酶与标准纤维素酶的活性比为22.60%,溶解性比为33.22%。     

纤维素酶在木质纤维素底物上的吸附、脱附以及循环利用

纤维素酶在木质纤维素底物上的吸附是一个复杂的物理化学过程,与纤维素酶和木质纤维素底物本身的性质密切相关,而且还受水解体系的各种参数,如缓冲溶液的浓度、pH、离子强度、温度、是否添加表面活性剂等影响。酶解结束时,大量的纤维素酶吸附在残余底物上。回收吸附在残余底物上的纤维素酶,是降低生物乙醇生产中纤维素酶成本的重要策略。缓冲溶液的pH、温度、是否添加表面活性剂等也对纤维素酶的脱附有着重要的影响。本文综述了影响纤维素酶吸附、脱附的各种参数;总结了纤维素酶脱附领域的研究进展以及纤维素酶循环利用的基本流程。     

浅析纤维素酶在酒精生产中的应用

纤维素酶是一种重要的酶产品,在酒精生产中具有重要的作用。从纤维素酶的作用上看,在分解纤维素时起生物催化作用,是酶制剂工业中的一个新的增长点。如何在酒精生产中应用纤维素酶是当前酒精生产关注的焦点。因此,研究纤维素酶在酒精生产中的应用具有十分重要的现实意义。文章以纤维素酶为切入点,在概述纤维素酶的基本内涵的基础上,重点探讨了纤维素酶在酒精生产中的应用,以期指导实践。     

影响纤维素酶活力测定的几个因素

鉴于当前尚无纤维素酶的酶活力测定的标准方法 ,也没有用以评价纤维素酶活力的统一的测量单位 ,我们研究了各种因素 ,其中包括底物的特性和浓度、纤维素酶的浓度、反应时间和反应温度以及DNS的数量等等对测定纤维素酶酶活的影响。研究表明 ,改变这些因素 ,会得到不同的纤维素酶酶活的测值。因此 ,应根据纤维素酶的特性使上述因素成为最佳条件。这样 ,我们就可能建立起统一的测定纤维素酶活力的方法。     

纤维素酶转化木质纤维素生物质生产乙醇的研究进展

木质纤维素生物质是价廉易得、来源丰富的可再生资源和能源，被纤维素酶转化后可以生产乙醇部分替代石油，这不仅有利于环境保护和资源再利用，而且可减少温室气体的排放和缓解化石能源的危机。纤维素酶成本的降低以及纤维素转化效率的提高是纤维素酶转化木质纤维素生物质生产乙醇的关键。本文综述了纤维素酶转化木质纤维素生物质生产乙醇的研究进展，主要包括纤维素酶的分类及其作用机制、纤维素酶的生产、木质纤维素生物质的预处理、纤维素酶的转化和糖化发酵乙醇工艺。     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

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 on Economic Indicators from 62 Enterprises in Printing Machinery Industry in Q1 2014

Operation of printing machine industry was still unsatisfactory in the first quarter of 2014.Analysis on operation of printing machine industry.a.Market demand was not strong;sales of product undulated and declined.According to the statistics,the total industrial output value fell by 19.28% in the first quarter of 2014 than the average quarter value in 2013; industrial added value decreased by 4.16%; sales revenue dropped by 22.83%. h. Business operation of enterprises was in poor condition. c. R＆D of new products is an important transformation guarantee for enterprises. d. To take self explore new ways upgrading advantages,and explore new ways.