新型功能性低聚糖的生产与研究

综述了功能性低聚糖的生产制备方法及各自的特点。功能性低聚糖因具有独特的生理功能,是目前食品工业研究开发的热点。迄今为止,制备途径主要可分为以下４种：（１）由天然植物中提取;（２）糖基转移,包括化学转移和酶转移;（３）聚合法,包括化学聚合与酶聚合;（４）多糖降解,包括化学降解和酶法降解。     

新型功能性低聚糖的生产与研究

综述了功能性低聚糖的生产制备方法及各自的特点,功能性低聚糖因具有独特的生理功能,是目前食品工业研究开发的热点,迄今为止,制备途径主要可分为以下４种：（１）由天然植物中提取;（２）糖基转移,包括化学转移和酶转移;（３）聚合法,包括化学聚合与酶聚合;（４）多糖降糖,包括化学降解和酶法降解。     

聚丙烯酰胺凝胶柱分离提纯木低聚糖的研究

木低聚精因具有独特的生理活性而成为一种重要的功能性食品基料,已引起全世界的广泛关注,其中分离提纯是制备功能性木低聚糖的关键技术之一。利用聚丙烯酰胶凝胶（Bio－GelP－4）柱层析能将木低聚糖混合样品较好地分离开来。当分离条件为：层折桂尺寸Φ3．0×120cm,脱离子水为洗脱液,流速25mL／h,柱温50℃,可以得到木二糖-木四糖的单—组分。研究表明,采用AmineXHPX－42A精柱是测定低聚糖简便快速的好方法。此外还介绍了通过测定各份洗脱液的糖浓度来初步判断分离效果的一种简单、快速和经济的分析方法。     

聚丙烯酰凝胶柱分离提纯木低聚糖的研究

木低聚糖因具有独特的生理活性而成为一种重要的功能性食品基料,已引起全世界的广泛关注,其中分离提纯是制备功能性木低聚糖的关键技术之一。利用聚丙烯酰胺凝胶柱层析能将木低聚糖混合样品较好地分离开来。当分离条件为：层析柱尺寸φ３．０×１２０ｃｍ,脱离子水为洗脱液,流速２５ｍＬ／ｈ,柱温５０℃,可以得到木二糖￣木四糖的单一组分。研究表明,采用Ａｍｉｎｅｘ ＨＰＸ－４２Ａ糖柱是测定低聚糖简便快速的好方法。此外     

1,6-六亚甲基二氨基甲酸酯合成研究进展

综述了几种合成1,6-六亚甲基二氨基甲酸酯（HDU）的路线,包括氯代甲酸酯胺解法、胺氧化羰化法、尿素醇解法和碳酸二甲酯 (DMC) 胺解法,认为碳酸二甲酯胺解法原料毒性小,过程温和,环境友好最具工业应用前景。对碱和L酸等碳酸酯胺解催化剂的研究进展进行了介绍和评述,认为开发低成本和易回收利用的高效胺解催化剂是提高HDU合成过程效率的关键。     

非光气法催化合成碳酸二苯酯研究进展

综述了近年来酯交换法、苯酚氧化羰化法、草酸二甲酯和苯酚交换、脱羰法和尿素酚解法4种非光气法催化合成碳酸二苯酯（DPC）的研究进展,包括每种合成法所使用的催化剂、反应条件、反应物的转化率和产物的收率,指出了每种合成法的优缺点,并从原料来源的难易、催化剂制备的成本、产物的收率、生产工艺的复杂性、能耗等方面进行分析比较,指出选用酯交换法和尿素酚解法生产碳酸二苯酯较为有利,这两种合成法可能是未来研究的重点。     

锂离子电池正极材料LiFeP04合成方法综述

LiFePO4是一种重要的锂离子电池正极材料。综述了几种常见的LiFePO4合成方法（主要包括固相法、微波法、碳热还原法、机械力化学活化法、水热法、溶胶凝胶法、液相沉淀法、微乳液干燥法、喷雾热解法等）及其特点,主要介绍近10年来国内外在此方向的重要研究成果及进展。     

酶法生产低聚糖

该“九五”项目利用高效生物反应器技术、高效酶转化技术开发了甘露低聚糖、异麦芽低聚糖、木低聚糖、果低聚糖及壳低聚糖等。解决了低聚糖生产用酶发酵、低聚糖片段的选择控制、生化工程制备等关键技术。在低聚糖转化率、收率以及应用方面都达到了世界先进水平,同时实现了低聚糖在功能性食品、农药中的应用,开发出新产品。     

工业油脂,油脚高温高压水解新工艺,新设备

工业油脂、油脚高温高压水解新工艺、新设备刘勇王纲群陈星虞剑波（安徽省应用技术研究所，宿州市，２３４０２３）工业油脂（包括油脚，下同）的水解是指油脂与水作用，生成脂肪酸和甘油的反应。油脂的水解方法主要有：皂化酸解法，酸性水解法，高温高压水解法等。皂化酸...     

双乙烯酮的合成及衍生物的开发

双乙烯酮的合成方法有多种，但惟一有工业价值的是乙烯酮二聚法。根据乙烯酮合成原料的不同可分为乙酸（醋酸）高温裂解法、乙炔氧化法、丙酮热解法和乙酸酐热解法。这4种方法的比较见表1。     

Pilot‐plant production of xylo‐oligosaccharides from corncob by steaming,enzymatic hydrolysis and nanofiltration

This paper reports a pilot‐plant production process for xylo‐oligosaccharides (mainly xylobiose and xylotriose) from corncob meal by steaming treatment followed by enzymatic hydrolysis and nanofiltration. The effects of corncob meal pretreatment, steaming temperature and time were investigated in order to obtain maximum extraction of xylan and to minimize the autohydrolysis of xylan into xylose. The enzymatic reaction was carried out using Aspergillus niger AN‐1.15 endo‐xylanase at 55 °C and the optimum enzymatic hydrolysis time was 5 h. The conventional downstream processing for purification of xylo‐oligosaccharides was incorporated with nanofiltration technology, giving benefits of energy saving and removal of monosaccharides. The final product from 40 kg of corncob meal was 10 dm³ of xylo‐oligosaccharide syrup (800 g dm^?3 total sugar), containing 74.5% xylobiose and xylotriose. Copyright © 2004 Society of Chemical Industry     

Extractive bioconversion of xylan for production of xylobiose and xylotriose using a PEG6000/sodium citrate aqueous two-phase system

Aqueous two-phase system (ATPS) was applied for extraction bioconversion of xylan by xylanase from Trichoderma viride. Phase diagrams for poly (ethylene glycol) (PEG) and sodium citrate were determined at room temperature. The ATPS composed of 12.99% (w/w) PEG6000 and 12.09% (w/w) sodium citrate was favorable for partition of xylanase and used for extraction bioconversion of xylan. Batch hydrolysis demonstrated that higher concentrations of xylobiose and xylotriose were obtained in the PEG6000/sodium citrate ATPS compared to those in the aqueous system. These results present the potential feasibility of production of xylo-oligosaccharides by extraction bioconversion in ATPS.     

Improvement of a fed‐batch process for high level xylanase production by a Bacillus strain

In this paper, the improvement of a fed‐batch fermentation from the point of view of an industrial xylanase production process is described. The Bacillus strain chosen for this study is able to produce high quantities of a xylanase that is suitable to be used as bleach boost agent in chlorine‐free bleaching sequences of paper pulp. It was found that xylo‐oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1 g dm^?3 xylose equivalents led to catabolite repression. A substrate‐limited fed‐batch process, that is the most adapted, was furthermore improved with regard to nutrient requirement of the microorganism, especially the nitrogen source. A process with constant supply of a culture medium containing xylan, peptone and mineral nitrogen was able to produce 20 240 nkat cm^?3 with a productivity of 910 nkat cm^?3 h^?1, which places the process among the best ever reported. © 2001 Society of Chemical Industry     

Wet oxidation pretreatment of lignocellulosic residues of sugarcane,rice, cassava and peanuts for ethanol production

Wet oxidation (WO) pretreatment of sugarcane bagasse, rice hulls, cassava stalks and peanut shells was investigated. WO was performed at 195 °C for 10 min, with 2 g kg^?1 of Na₂CO₃ and under either 3 or 12 bar of oxygen. Oxygen pressure and the type of raw material used had a major effect on the fractionation of the materials, formation of sugars and by‐products, and cellulose enzymatic convertibility. Cellulose content in the solid fraction increased after pretreatment of all materials, except rice hulls. The greatest increase, from 361 g kg^?1 to almost 600 g kg^?1, occurred for bagasse. The solubilisation of individual components was different for each material. Bagasse xylan was solubilised to a large extent, and 45.2% of it was recovered as xylose and xylo‐oligosaccharides in the liquid fraction. In the prehydrolysates of rice hulls around 40% of the original glucan was recovered as gluco‐oligosaccharides, due to hydrolysis of starch contained in grain remains. The formation of by‐products was modest for all the materials, but increased with increasing oxygen pressure. The highest yield of acetic acid (34–36 g kg^?1 of raw material) and furfural (0.7–1.8 g kg^?1) occurred for bagasse. The pretreatment enhanced the enzymatic convertibility of cellulose giving the best result (670.2 g kg^?1) for bagasse pretreated at the highest oxygen pressure. However, for the other materials the pretreatment conditions were not effective in achieving cellulose conversions above 450 g kg^?1. Some enzymatic conversion of xylan was observed. Copyright © 2007 Society of Chemical Industry     

Reaction mechanisms and kinetics of xylo‐oligosaccharide hydrolysis by dicarboxylic acids

Hydrothermal pretreatment of lignocellulosic materials generates a liquid stream rich in pentose sugar oligomers. Cost‐effective hydrolysis and utilization of these soluble sugar oligomers is an integral process of biofuel production. We report integrated rate equations for hydrolysis of xylo‐oligomers derived from pretreated hardwood by dicarboxylic maleic and oxalic acids. The highest xylose yield observed with dicarboxylic acids was 96%, and compared to sulfuric acid, was 5–15% higher with less xylose degradation. Dicarboxylic acids showed an inverse correlation between xylose degradation rates and acid loadings unlike sulfuric acid for which less acid results in less xylose degradation to aldehydes and humic substances. A combination of high acid and low‐temperature leads to xylose yield improvement. Hydrolysis time course data at three different acid concentrations and three temperatures between 140 and 180°C were used to develop a reaction model for the hydrolysis of xylo‐oligosaccharides to xylose by dicarboxylic acids. © 2012 American Institute of Chemical Engineers AIChE J, 59: 188–199, 2013     

Hydrothermal processing of rice husks: effects of severity on product distribution

BACKGROUND: Treatment in aqueous media (hydrothermal or autohydrolysis reactions) is an environmentally friendly technology for fractionating lignocellulosic materials. Rice husks were subjected to hydrothermal processing under a variety of operational conditions to cause the selective breakdown of xylan chains, in order to assess the effects of reaction severity on the distribution of reaction products. RESULTS: The effects of severity (measured by the severity factor, R₀) on the concentrations of the major autohydrolysis products (monosaccharides, xylo‐ and glucooligosaccharides, xylooligosaccharide substituents, acetic acid, acid‐soluble lignin and elemental nitrogen) were assessed. The interrelationship between the severity of treatment and molecular weight distribution was established by high‐performance size‐exclusion chromatography. Selected samples were subjected to refining treatments as ethyl acetate extraction and ion exchange for refining purposes, and the concentrates were assayed by high‐performance anion‐exchange chromatography and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. CONCLUSIONS The protein equivalent of the products present in liquors accounted for 43 to 51% of the protein present in the raw rice husks. The concentrations of glucose (derived from starchy material) and arabinose (split from the xylan backbone) were fairly constant with severity. Even in treatments at low severity, high molecular weight compounds derived from xylan accounted for a limited part of the stoichiometric amount. Operating under harsh conditions, about 50% of the total xylan‐derived compounds corresponded to fractions with a degree of polymerization (DP) < 9. After refining, saccharides accounted for more than 90% of the non‐volatile components of the sample. The refined products showed a series of xylose oligomers up to about DP 13, and a series of acetylated xylose oligomers up to about DP 15. Copyright © 2008 Society of Chemical Industry     

Enzymatic production of Xylooligosaccharide from selected agricultural wastes

Four different agricultural wastes, namely tobacco stalk (TS), cotton stalk (CS), sunflower stalk (SS) and wheat straw (WS) were tested for the production of Xylooligosaccharide (XO). XO production was performed by enzymatic hydrolysis of xylans which were obtained by alkali extraction from the agricultural wastes. Depending on the source, it was found that these four agricultural wastes contained different amount of xylan, cellulose and lignin and the xylan obtained from these source contained different amount of sugar and uronic acid. The highest amount of arabinose was in xylan from WS while the other xylans mainly had xylose and small amount of glucose. Different xylanase preparations were evaluated for production XO from these xylan sources. Aspergillus niger xylanase produced lower amount of XO from wheat straw xylan (WSX) than cotton stalk xylan (CSX), sun flower xylan (SSX) and tobacco stalk xylan (TSX) while Trichoderma longibrachiatum xylanase hydrolyzed highly branched WSX better. The HPLC analysis of the hydrolysis products indicated that depending on structure and composition of xylan, A. niger xylanase produced less amount of xylose than T. longibrachiatum xylanase, and the hyrolysis product of A. niger xylanase contained different amount of oligosaccharides (X2 > X3 > X4 > X5 > X6, >X6). Regardless of the structural differences of the xylan types presented in this paper, all xylans generated XO with different degree of polymerization (DP), but the DP of XO depended on the enzyme specificity and the structure of substrate.     

凝胶过滤色谱法研究酶解过程中木聚糖分子结构的变化

采用凝胶过滤色谱法研究了木聚糖在酶解过程中分子量分布的变化。结果表明,木聚糖酶对高分子量组分的木聚糖的降解能力较差,而主要降解分子量介于15000～3000之间组分的木聚糖,使得这部分木聚糖变为分子量更低的木聚糖组分。随着酶解时间的延长,酶解得率上升,酶解产物中低聚木糖含量增多,未被酶解的木聚糖的平均聚合度上升,当酶解时间超过4h时,这种变化趋势缓慢。随着酶解轮次的增加,酶解产物中可溶性木聚糖的含量越来越少,木聚糖被降解的难度越来越大。在实际生产中,用来作为低聚木糖生产的木聚糖其聚合度应在20～100之间,酶解时间以4h为宜,重复利用未水解木聚糖的轮次以2轮为宜。     

Production of Xylooligosaccharides from Waste Xylan,Obtained from Viscose Fiber Processing,by Selective Hydrolysis Using Concentrated Acetic Acid

Xylooligosaccharides (XOS) were prepared by selective hydrolysis of the waste xylan, obtained from viscose fiber plants, using concentrated acetic acid. The influences of acetic acid concentration, reaction temperature, and reaction time on the yield and component profiles of XOS product were investigated. These results were further ascertained by designing orthogonal experiments. The hydrolysis of xylan residue was selective, since mainly xylooligosaccharide components were formed, with hardly any impure ingredients, except for a small amount of xylose and traces of furfural, in the hydrolyzed product. Reaction temperature was found to be the most significant factor, influencing the XOS yield. Accurate HPAEC–PAD analysis of component profiles indicated that a maximum XOS yield of 45.86% was achieved on hydrolysis of 33.77 g/L waste xylan using 20% acetic acid for 20 min at 140°C. The main XOS components obtained were xylobiose, xylotriose, and xylotetraose, which were more than xylopentaose and xylohexaose.     

水热预处理竹子促进酶解的效果及其影响因素

采用间歇式水热预处理装置,研究了水热预处理用于竹子的酶解规律,探讨了不同温度、处理时间、纤维素酶添加量及原料种类对促进竹子酶解的效果及其影响。结果表明水热预处理能显著提升竹子的酶解率,在优化条件190℃、10 min水热预处理,添加15 FPU·(g葡聚糖)^-1纤维素酶,72 h葡聚糖与木聚糖酶解率分别为74.3%、54.0%,提高到原来的3.5倍和4.7倍。过高的预处理温度与过长的预处理时间都将导致木糖大量降解和部分葡萄糖降解,使单糖总量下降。纤维素酶的添加量从15 FPU·(g 葡聚糖)^-1提高到60 FPU·(g 葡聚糖)^-1,可使未作预处理和水热预处理竹子的总糖回收率分别提高21.5%和9.9%,其促进酶解的作用远低于预处理的效果,通过预处理增大酶的可及性是提高酶解率的关键。水热预处理对于生物质原料具有选择性,不同的竹子原料具有显著不同的效果。