不同木素降解成分对纤维素降解的影响

用经过驯化的瘤胃菌厌氧降解加入不同木素降解成分的纤维素，结果表明，木素中的香兰素对瘤胃微生物降解纤维素降解的启动有明显影响，但不影响其最终降解程度，香兰素对乙酸、丁酸的产生有促进作用，但对丙酸的产生有抑制作用；乙酰基愈创木酚和愈创木酚对纤维素的降解影响不大，对降解启动略有影响，愈创木酚对丙酸的产生也有抑制作用，但不如香兰素的抑制作用强，而乙酰基愈创木酚对丙酸的产生无影响。混合态的酸淅木素对纤维素降解有明显的抑制作用。     

纤维素的微生物降解研究进展

纤维素是自然界储量最丰富的可再生生物质原料,具有解决能源危机的巨大潜力,但结构复杂,难以降解,导致综合利用率较低。利用微生物处理技术降解纤维素,是实现其循环利用的一项重要策略。本文从单一菌株、天然复合菌群、优化组合纯培养菌株三个方面对纤维素的微生物降解进行了综述,总结归纳了每种筛选策略的优势特点和应用价值,并阐述了纤维素的微生物降解机理,对其未来发展提出了展望,旨在为探索更高效的纤维素降解新思路提供借鉴。     

瘤胃微生物体外驯化降解纤维素研究

实验先按照正交表L18(3^7）的设计对瘤胃微生物降解滤纸的营养和环境条件进行研究，发现在C/N为14.2/1、葡萄糖浓度低、乙酸浓度为800mg/L、无丙酸存在，温度为45℃、pH值为6.5的环境条件下，纤维素的降解校为彻底。在以上优化条件的基础上，进行了纤维降解及产酸情况的研究，发现纤维素降解的直接产物葡萄糖不会产生积累而很快就转化为挥发酸，而挥发酸会产生积累。挥发酸主要是乙酸、丙酸和丁酸三种，其中乙酸产量占到86%-93%。在纤维素降解产酸过程中，产气量并不大。     

基于纤维素的食品包装材料的研究进展

纤维素多数来源于植物和微生物,具有优良的生物降解性和力学性能,可在绿色食品包装材料中广泛应用。本文综述了来自于植物和微生物的木质纤维素、微纤维纤维素及细菌纤维素的提取、改性方法以及其在食品包装材料中的力学性能、阻隔性、抗菌性、降解性能等方面的相关研究。纤维素作为食品包装材料不仅拓展了纤维素的应用领域,而且为食品安全和环境保护提供了保障,相信随着纤维素提取和改性技术的不断进步,未来纤维素在食品包装领域的应用会备受关注。     

外源酶对湖羊瘤胃微生物区系的影响

研究添加不同水平的外源酶(木聚糖酶和纤维素酶)对湖羊瘤胃液体外培养及瘤胃微生物体外培养区系的影响,旨在为外源酶作为湖羊饲料添加剂开发提供理论依据。结果表明:添加不同水平外源酶均能改善瘤胃微生物体外培养特性,其中以添加量为10mg/kg处理组效果最佳,外源酶(10mg/kg)可以有效提高培养液中细菌浓度(P0.01),产甲烷菌浓度极显著降低(P0.01),促进纤维素降解菌生长繁殖。     

冬小麦扩展蛋白TaEXPA8黑曲霉工程菌的构建及纤维素水解作用分析

农作物秸秆中大量存在的纤维素是可再生的清洁能源之一,纤维素的充分利用对于自然资源的可持续发展及环境保护有重要意义。然而,秸秆中纤维素的复杂结构使其降解工作较难开展。扩展蛋白是存在于植物及部分微生物中的一类细胞壁松弛蛋白,且来自于微生物中的扩展蛋白被证实能够提高纤维素酶的水解效率。为探究植物中扩展蛋白协同纤维素酶提高降解纤维素的能力,该研究以冬小麦扩展蛋白TaEXPA8为基础构建了黑曲霉表达载体,并以黑曲霉CICC2462为受体获得了黑曲霉工程菌pSZHGS-TaEXPA8,同时对该工程菌发酵液的纤维素水解促进作用进行了分析。结果显示,TaEXPA8基因能够在工程菌中进行正常的转录,并在发酵上清液中检测到TaEXPA8蛋白的表达,但表达量较低;工程菌的发酵液能够显著促进滤纸的崩解,水解作用产生葡萄糖的含量相比于单一纤维素酶处理提高了21.2%。该研究为植物扩展蛋白在纤维素降解中的应用提供新的思路和方法。     

木质素的生物降解及其应用

综述了具有降解木质素能力的微生物和酶的种类及其降解特性,阐述了木质素生物降解在生物化学制浆、纸浆生物漂白、造纸废水生物处理、饲料工业、生物肥料等领域的应用现状,展望了木质素生物降解技术研究的发展趋势.     

羧甲基纤维素的制备研究及应用现状

羧甲基纤维素是一种水溶性纤维素醚,具有多种重要生物活性,广泛应用于食品、化工等领域。本文综述了羧甲基纤维素及其交联聚合物的制备工艺研究进展,阐述了羧甲基纤维素在各食品领域的应用现状,并对其发展前景进行了展望,拟为羧甲基纤维素的进一步研究奠定基础。     

苹果酸对山羊瘤胃纤维降解率及发酵类型的影响

以4头装有永久性瘤胃瘘管的本地山羊为试验动物,采用4×4拉丁方设计,研究苹果酸(0、5、10和15 g/d)对山羊瘤胃纤维降解率及瘤胃发酵类型的影响。结果表明,日粮中添加苹果酸能够显著提高瘤胃内中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的降解率(P<0.05);瘤胃液中乙酸与丙酸比值显著降低(P<0.05),改变了瘤胃发酵类型;氨态氮浓度显著降低(P<0.05),促进了瘤胃微生物对氨、氮的利用。     

纳米纤维素/二维材料纳米复合材料在水处理领域的应用进展

近年来,纳米纤维素在水处理领域受到广泛关注。纳米纤维素的羟基对带有离子结构的污染物表现出一定的吸引力,通过表面改性还可进一步提高其捕获能力。将纳米纤维素和石墨烯等二维材料复合能够制备高性能纳米复合材料,提高材料对污染物的选择性。本文介绍了纳米纤维素和常见的几种二维材料,综述了纳米纤维素/二维材料复合材料在水处理领域的应用,包括过滤、吸附、光催化降解3种处理方法,并对不同二维材料与纳米纤维素复合后在水处理领域应用中的差异进行了比较。     

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.     

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.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.     

Analysis for organic residues from aids to polymerization used to make plastics intended for food contact

Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography-mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (¹     

Tests of potential functional barriers for laminated multilayer food packages. Part II: Medium molecular weight permeants

Experiments were performed to characterize the kinetics of the permeation of different medium molecular weight model permeants: bisphenol A, warfarin and anthracene, from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick orientated polypropylene--OPP) into the food simulants olive oil and 3% (w/v) acetic acid. The characterization of permeation kinetics generally observed the permeation models previously reported to explain the experimental permeation results obtained for a low molecular weight group of model permeants. In general, the model permeants exhibited behaviour consistent with their relative molecular weights with respect to (a) the time taken to attain steady-state permeation into the food simulant in which they were more soluble, (b) their subsequent steady-state permeation rates, and (c) their partition between liquid paraffin and the OPP membrane.     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. I: Interlaboratory studies of methods of analysis

This paper describes the first part of a project undertaken to develop mussel reference materials for Paralytic Shellfish Poisoning (PSP) toxins. Two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin (STX) and decarbamoyl-saxitoxin (dc-STX) in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the second part of the project: the certification exercise. In the first study, 18 laboratories were asked to measure STX and dc-STX in rehydrated lyophilized mussel material and to identify as many other PSP toxins as possible with a method of their choice. In the second interlaboratory study, 15 laboratories were additionally asked to determine quantitatively STX and dc-STX in rehydrated lyophilized mussel and in a saxitoxin-enriched mussel material. The first study revealed that three out of four postcolumn derivatization methods and one pre-column derivatization method sufficed in principle to determine STX and dc-STX. Most participants (13 of 18) obtained acceptable calibration curves and recoveries. Saxitoxin was hardly detected in the rehydrated lyophilized mussels and results obtained for dc-STX yielded a CV of 58% at a mass fraction of 1.86 mg/kg. Most participants (14 out of 18) identified gonyautoxin-5 (GTX-5) in a hydrolysed extract provided. The first study led to provisional criteria for linearity, recovery and separation. The second study revealed that 6 out of 15 laboratories were able to meet these criteria. Results obtained for dc-STX yielded a CV of 19% at a mass fraction of 3.49mg/kg. Results obtained for STX in the saxitoxin-enriched material yielded a CV of 19% at a mass fraction of 0.34mg/kg. Saxitoxin could not be detected in the PSP-positive material. Hydrolysis was useful to confirm the identity of GTX5 and provided indicative information about C1 and C2 toxins in the PSP-positive material. The methods used in the second interlaboratory study showed sufficiently consistent analysis results to undertake a certification exercise to assign certified values for STX and dc-STX in lyophilized mussel.     

Focus on China's Paper Industry

In the English section of this issue, 〈China Paper Newsletters〉 will introduce ＂National Development and Reform Commission Issued Announcement for Selection of Major Preliminary Research Projects for the ＇13th Five-Year Plan＇＂, ＂2013 Annual Report of China＇s Paper Industry＂, and news of projects and other policies.     

Listen to downstream & search for innovation

正Nowadays,textile enterprises are all taking efforts in transformation and upgrading,like improving producing capacity and optimizing production structure to face market downturn.It claimed a higher request to the standard of textile equipments.In the upcoming of ITMA ASIA+CITME 2014exhibition,this magazine have interviewed several branch associations and a series of relative enterprises,to summarize industrial developing status