从阿拉伯胶水解液中结晶分离L-阿拉伯糖

阿拉伯胶水解液经结晶法提纯制备出粗L-阿拉伯糖.研究了时间、温度、pH值和溶剂对L-阿拉伯糖结晶率和纯度的影响,得到了由阿拉伯胶水解液中结晶分离L-阿拉伯糖适宜的工艺条件.该方法操作简便,生产效率高,易于工业化生产.     

L-阿拉伯糖研究进展

综述了L-阿拉伯糖的最新研究进展.内容包括:L-阿拉伯糖的提取及用途、L-阿拉伯糖的传统提取工艺和设备的改进以及L-阿拉伯糖的合成.     

阿拉伯糖催化制取L-核糖的工艺研究

本文对L-阿拉伯糖差相异构反应生成L-核糖进行了实验研究;通过正交试验分析确定了最佳阿拉伯糖转化条件:PH值2.5、反应温度95℃、钼酸铵加入量0.5%、糖液浓度15%,L-阿拉伯糖的转化率达16.9%。     

从L-阿拉伯胶提取L-阿拉伯糖

阿拉伯胶在硫酸作用下水解得到含L 阿拉伯糖的混合液,经w(C2H5OH)=90%的乙醇萃取,再经工业乙酸沉淀,可得粗L 阿拉伯糖。正交实验确定了酸性水解反应的影响因素和最佳条件为:水解温度90～100℃,w(H2SO4)=1 0%,L 阿拉伯糖的粗收率为85%,质量分数为66 7%。经双柱色谱分离提纯L 阿拉伯糖,所用洗脱剂分别为:V(正丁醇)∶V(乙酸乙酯)∶V(异丙醇)∶V(乙酸)∶V(水)=3 5∶10∶6 5∶3∶3和V(乙酸乙酯)∶V(异丙醇)∶V(水)=5∶2 2∶1 1,得到收率大于50%,质量分数为99%的L 阿拉伯糖。     

L-阿拉伯糖研究进展

L-阿拉伯糖是一种新兴的低热量功能性糖,在自然界中,广泛存在于玉米皮、甜菜根、阿拉伯胶等中。L-阿拉伯糖在血糖、血脂的调节方面有广阔的前景。本文综述了L-阿拉伯糖的制备方法,并介绍了L-阿拉伯糖的性质,展望了L-阿拉伯糖生产的发展趋势。     

酸催化水解蔗糖制取乙酰丙酸

以蔗糖为原料,在H2SO4催化下制备乙酰丙酸,主要考察了反应时间、反应温度、蔗糖浓度、H2SO4浓度对乙酰丙酸产率的影响。实验结果表明,反应时间60min,反应温度110℃,蔗糖浓度0.4mol/L,H2SO4浓度3.5mol/L条件下乙酰丙酸的产率最高。     

L-丙氨酸催化加氢制备L-氨基丙醇反应优化

使用B．u／C作为催化剂，以L一丙氨酸为原料催化加氢制备L一氨基丙醇，考察了反应温度、H：压强、原料溶液pH值以及活性炭载体硝酸改性等因素对反应的影响，并对以上因素进行了优化。     

阿拉伯糖和其他糖类复聚衍生物发展动向

阿拉伯糖和其他糖类结合的复聚衍生物广泛存在于自然界,且对人体健康有重要的生理功能。但自然界并无游离的阿拉伯糖存在,需由人工从阿拉伯糖的复聚衍生物中提取。国内自2008年卫生部批准L阿拉伯糖单糖为新资源食品以来,对阿拉伯糖的功能有较多的报导,但对于阿拉伯糖和其他糖类复聚衍生物的报导较少。为使读者能更多地了解阿拉伯糖、阿拉伯糖和其他糖类复聚衍生物的发展动向,本文对其进行简要介绍。     

低酸催化水解稻草制备腐植酸的工艺研究

试验采用低酸催化水解工艺,从稻草中提取腐植酸.根据单因素试验设计,通过测定水解过程中稻草纤维素转化率和腐植酸产率的变化指标,来寻求较佳工艺参数.结果表明,初始阶段反应条件为温度220℃、0.1%硫酸溶液、固液比1∶12、压力4 MPa、转速300 r/min、时间20 min,将反应釜的反应条件调整为温度70℃、转速3...     

自催化水解反应精馏制草酸工艺

开发了草酸二乙酯水解反应精馏技术制备草酸的工艺过程,研究了塔顶出料量、进料配比、回流比及进料位置等工艺条件对草酸二乙酯转化率的影响,确定较好工艺条件:塔顶采出率0.17—0.20、进料摩尔比:18—24、回流比2—3,草酸二乙酯的转化率可达到97%以上。     

中低温羰基硫催化水解技术研究进展

对羰基硫水解催化剂、水解反应动力学和反应机理等研究现状进行了评述。指出添加抗中毒助剂制备高活性催化剂、将醇胺脱硫体系与水解法相结合以及采用水滑石吸附法同时脱除H₂S和COS是未来这一领域的研究热点。     

PB试验和BBD响应面优化酶解鱼鳞制备抗菌肽工艺

以酶解液的多肽含量和抑菌活性作为考察指标,采用酸性蛋白酶酶解制备草鱼鱼鳞抗菌肽。在单因素的基础上,运用PB试验设计进行影响因素的显著性筛选,确定出显著性影响因素为pH、温度和时间,进而通过BBD试验得到草鱼鱼鳞抗菌肽制备的最佳工艺条件为:pH 2.72、40.22℃、97.33min,在该条件下酶解液对金黄色葡萄球菌的抑菌圈直径为18.49mm,对大肠杆菌的抑菌圈直径为17.31 mm。结果表明,利用酸性蛋白酶酶解制备草鱼鱼鳞抗菌肽是行得通的,为草鱼鱼鳞等下脚料实现低值原料高值化提供了新的思路。     

CO气氛中液相催化COS水解活性的研究

在鼓泡反应器中，采用液相催化剂，对高浓度CO气氛中高浓度COS的水解反应进行考察，研究催化剂浓度、气液体积比、温度的变化对COS水解转化率及催化体系稳定性的影响，得出最佳工艺条件，并对反应机理进行初步探讨。结果表明,COS水解转化率随气液体积比增大而降低，随催化剂浓度增大而升高；在常温、常压和气液体积比为150 h^－1的条件下，质量分数为10%的催化剂水溶液中COS的水解转化率可达100%，连续使用20 h转化率不变。     

Thermodynamic and Quality Properties of Lemon Juice Powder as Affected by Maltodextrin and Arabic Gum

Sorption isotherms of lemon juice (LE) powders with and without additives—18% maltodextrin (MA) or 18% gum Arabic (GA)—were determined at 20-50°C. Addition of additives was shown to affect the isotherms in such a way that, at the same water activity, samples LE + GA and LE + MA presented lower equilibrium moisture content and were not so affected by varying temperature. The net isosteric heats of sorption of juice powders with additives were higher (less negative) than those of lemon juice powders, suggesting that there are more active polar sites in the product without addition of GA or MA. In general, the quality properties decreased with the addition of maltodextrin and gum arabic and it was obtained similar values for LE + GA and LE + MA.     

醋酸甲酯水解用杂多酸类催化剂的筛选

针对醋酸甲酯水解悬浮催化蒸馏工艺的要求,对杂多酸盐类酸性材料用作醋酸甲酯水解反应的催化剂进行了探索。从催化反应性能以及结构稳定性等方面对杂多酸及其盐进行评价和表征。实验证明,不同杂多酸及其盐的催化性能与杂多阴离子和阳离子的种类、阳离子取代基数目等因素有关,其中NH4H2PW12O40催化性能最好,反应重复性能也比较好;杂多酸铵盐反应前后结构无明显变化,具有良好的结构稳定性;NH₄H₂PW₁₂O₄₀的酸强度和总酸量也较高。     

Thermodynamic and Quality Properties of Lemon Juice Powder as Affected by Maltodextrin and Arabic Gum

Sorption isotherms of lemon juice (LE) powders with and without additives—18% maltodextrin (MA) or 18% gum Arabic (GA)—were determined at 20–50°C. Addition of additives was shown to affect the isotherms in such a way that, at the same water activity, samples LE + GA and LE + MA presented lower equilibrium moisture content and were not so affected by varying temperature. The net isosteric heats of sorption of juice powders with additives were higher (less negative) than those of lemon juice powders, suggesting that there are more active polar sites in the product without addition of GA or MA. In general, the quality properties decreased with the addition of maltodextrin and gum arabic and it was obtained similar values for LE + GA and LE + MA.     

Characterization,Thermal, and Mechanical Behaviours of Gamma Irradiated Gum Arabic/Poly Vinyl Alcohol Polymer Blends

Polymer blends based on various compositions of natural macromolecule gum arabic (GA) and poly vinyl alcohol (PVA) were prepared by solution casting technique. It was found that the maximum concentration of gum from which a compatible blend can be obtained was found to be from 10–30%. Compatible blend were exposed to gamma irradiation at different doses of 20, 30, and 50 kGy to evaluate the effect of irradiation on different properties of the blend. Physical, thermal and mechanical properties of the blend were investigated. Also, structural properties in terms of scanning electron microscope (SEM) were studied. The Results obtained show a decrease in glass transition temperature of the blend with increasing GA content. Moreover, there is an improvement in mechanical properties in terms of stress-strain behavior.