壳聚糖微球的制备及其对脂肪酶的固定化研究

采用反相悬浮法制备壳聚糖微球,并以此作为载体固定了脂肪酶。对壳聚糖微球的制备条件、微球的性能及其固定化脂肪酶的条件进行了探讨,结果表明,壳聚糖微球成球效果最好的制备条件是壳聚糖溶液与分散相液体石蜡体积比为1∶2,吐温-80使用量为15mL,壳聚糖浓度为4%,所制得的壳聚糖微球具有良好的热稳定性、耐酸碱性和抗氧化性;壳聚糖微球固定化脂肪酶的最佳条件为戊二醛用量0.6mL,交联时间60min,加酶量1mg/g载体,pH值为7。采用壳聚糖微球固定化脂肪酶具有较高的酶活回收率,为60%     

壳聚糖固定化酶研究进展

介绍壳聚糖作为固定化酶载体的3种主要情况：壳聚糖直接作为固定化酶载体；壳聚糖衍生物作为固定化酶载体；壳聚糖与其他物质共同作为固定化酶载体。壳聚糖及其衍生物的固定化酶具有酶活性高、回收率高和耐贮藏等特点。指出壳聚糖及其衍生物在固定化酶技术领域有着广阔的应用前景。     

基于茶汤中应用的单宁酶固定化工艺研究

目的优化单宁酶固定方法,改善茶汤质量。方法采用壳聚糖、离子交换树脂和活性炭等易得原料作为载体对单宁酶进行固定化研究,最终确定用壳聚糖作为载体,采用吸附法制备固定化单宁酶。通过单因素和正交实验对壳聚糖作为载体制备单宁酶的条件进行优化。结果壳聚糖作为载体固定单宁酶的最佳条件为酶总活力80 U,吸附时间4 h,酶与载体吸附温度35℃,制得的固定化单宁酶酶活力回收最高。采用固定化单宁酶对茶汤进行处理并进行感官审评,经固定化单宁酶处理的茶汤和未经固定化单宁酶处理的茶汤在感官质量上有很大的差异。结论经固定化单宁酶处理的茶汤质量有很大改善,澄清效果显著。     

甲壳素、壳聚糖作为固定化酶载体的研究进展

介绍了甲壳素、壳聚糖作为载体的酶的固定化条件及固定化方法,并介绍其活力回收率及稳定性。甲壳素、壳聚糖来源丰富,可以通过多种方法进行处理用作固定化酶载体。     

壳聚糖溶液的制备和壳聚糖降解性的研究

研究了壳聚糖溶解过程工艺参数（溶剂、壳聚糖粒度、反应温度、反应时间）对所制壳聚糖溶液的粘度和酸度的影响,发现在溶解过程中既有过程中既有壳聚糖的溶解,又有溶解了的壳聚糖品质降解。研究了壳取糖溶液在存放过程中,存放温度和存放时间对壳聚糖降解的影响。探讨了壳聚糖及其溶解在溶解和存放过程中的降解规律,为制备在固定化酶等多方面应用所需性能的壳聚糖溶液提供了依据。     

聚糖凝胶固定β-D-半乳糖苷酶方法研究

以壳聚糖凝胶为载体,戊二醛为交联剂固定β-D-半乳糖苷酶,对壳聚糖凝胶的制备条件及乳糖酶的固定化条件进行了研究,确定了乳糖酶固定的最佳条件为:2.5%壳聚糖与2%戊二醛、1.0mg/mL的溶液酶,(pH值为7.0)固定9h,酶活力回收率为61.05%     

聚糖凝胶固定β-D-半乳糖苷酶方法研究

以壳聚糖凝胶为载体,戊二醛为交联剂固定β-D-半乳糖苷酶,对壳聚糖凝胶的制备条件及乳糖酶的固定化条件进行了研究,确定了乳糖酶固定的最佳条件为:2.5%壳聚糖与2%戊二醛、1.0mg/mL的溶液酶,(pH值为7.0)固定9h,酶活力回收率为61.05%     

壳聚糖固定化木瓜蛋白酶的研究

以壳聚糖为载体,戊二醛作为交联剂,采用载体交联法制备固定化木瓜蛋白酶,并研究了固定化木瓜蛋白酶的最佳固定化条件。结果表明:木瓜蛋白酶的最佳固定化条件为给酶量为40～50mg/g,于pH7.5,25～30℃下,0.4%～0.5%的戊二醛溶液交联12h,所得的固定化木瓜蛋白酶的活力回收率平均达61.6%。     

壳聚糖固定化超氧化物歧化酶的研究

目的:研究壳聚糖固定化超氧化物歧化酶的酶学性质。方法:分别以不同方法对超氧化物歧化酶进行固定并比较其活力,对固定化方法进行相应的优化,对固定化超氧化物歧化酶进行酶学性质测定。结果:以壳聚糖为载体,戊二醛交联法制备固定化超氧化物歧化酶,优化条件下制备的固定化酶,所得固定化酶活力为330U/g,酶活回收率为58.33%,热稳定性和酸稳定性较游离酶有很大的提高,且具有良好的贮存稳定性,固定化酶可实现反复使用,提高了利用率。结论:壳聚糖-戊二醛交联法可用于制备性能较优的固定化超氧化物歧化酶。     

壳聚糖微球固定化β-半乳糖苷酶

以壳聚糖为载体、戊二醛为交联剂固定化β-半乳糖苷酶,通过单因素和正交实验探讨了固定化载体和固定化条件对酶固定化的影响。结果表明,固定化载体壳聚糖(脱乙酰度90%以上)的最适分子质量和体积分数分别为3×105和2%,制备的壳聚糖载体具有良好的成球性和机械强度。采用交联方式将β-半乳糖苷酶固定在壳聚糖微球上,在单因素试验的基础上,进行正交试验确定固定化条件为:交联剂戊二醛浓度和交联时间分别为10 g/L和1.0 h,酶浓度和固定化时间分别为1.5 mg/m L和12 h,最终制备的固定化酶的活力回收率达到70.5%。同时该固定化酶具有良好的储存稳定性和操作稳定性,具有一定的应用价值。     

高速剪切作用对壳聚糖的降解效果研究

采用高速剪切技术对壳聚糖的机械降解过程进行了研究。考察了剪切时间、转速、温度、壳聚糖原溶液浓度、分子量和溶液pH等因素对壳聚糖降解效果的影响。以壳聚糖的动力黏度下降率来反映壳聚糖的降解程度,分别采用傅立叶变换红外光谱及凝胶渗透色谱对壳聚糖降解前后的结构和分子量分布进行了分析。研究结果表明,纯机械作用能够促进壳聚糖的降解,当壳聚糖原溶液浓度为3 g/L,分子量为100×104,pH为4.6,温度为40 ℃,降解时间为40 min,转速为20000 r/min时,降解效果最明显,动力黏度下降率为20.27%。研究还发现黏度对壳聚糖的机械降解过程有一定影响,当壳聚糖原溶液黏度为4.0 mPa·s时,壳聚糖的黏度下降率最大。本文为深入探究壳聚糖降解机理提供了理论依据。     

食品安全级固定化载体-壳聚糖微球制备的条件

研究壳聚糖固定化微球载体制备的最佳条件,为进一步用食品安全级载体——壳聚糖固定化乳糖酶提供理论基础。用凝聚/沉淀法制备壳聚糖微球载体。结果表明,20g/L壳聚糖(1%冰乙酸溶液),以距凝结液面20～30cm滴入终浓度20%NaOH和30%甲醇的凝结液中,液滴刚滴入时不搅拌。该条件下制得直径为(4.00±0.06)mm,平均重量(30.80±0.02)mg/个,每个壳聚糖载体的比表面积为4.08×10-4 m2/g,形状完整,大小均一,具有弹性。     

壳聚糖纺丝液流变性能改善方法初探

文章介绍了最近在改善壳聚糖纺丝液流变性能方面的研究现状。用均质处理器对壳聚糖纺丝液进行了处理。结果发现均质处理会使壳聚糖纺丝液的静态表观粘度降低,同时,在一定范围内,使得壳聚糖纺丝液的动态表观粘度有明显升高。     

尿素对壳聚糖溶液黏度及其膜溶胀率的影响

本文研究了尿素浓度对壳聚糖溶液黏度的影响,同时考察了壳聚糖膜在不同pH值缓冲液中的溶胀率.结果表明,（1）尿素可以明显降低壳聚糖溶液的黏度.（2）在pH为5.4和6.6的缓冲液中,尿素的添加量与壳聚糖膜的溶胀率成反比;在pH为2.4的缓冲液中,尿素的添加量与壳聚糖膜的溶胀率成正比.（3）尿素是一种良好的壳聚糖包膜营养素过瘤胃的辅料,其适宜浓度为0.3%.     

Preparation,water solubility and rheological property of the N-alkylated mono or disaccharide chitosan derivatives

N-alkylation of chitosan was performed in a mixture of methanol and 1% acetic acid containing different amounts of monosaccharides or disaccharides including glucose, galactose, glucosamine, fructose, lactose, maltose and cellobiose. All the N-alkylated chitosan derivatives with monosaccharides were insoluble in aqueous solution (pH 7), while N-alkylated chitosan derivatives with disaccharides were easily soluble in distilled water, and the N-alkylated chitosan derivatives with lactose were soluble only at high pH. The degree of substitution (DS) of the N-alkylated chitosan derivatives increased with increasing disaccharides levels and with increasing reaction time. The reduced viscosity of the N-alkylated chitosan derivatives with disaccharides decreased with increasing DS. Apparent viscosity and pseudoplasticity of the N-alkylated disaccharide containing derivative solutions generally decreased with increasing DS. Although apparent viscosities of N-alkylated chitosan derivatives with low DS decreased with increase in pH or ionic strength, changes in high DS N-alkylated chitosan derivatives with pH values or ionic strength were not marked.     

氧气对涡流空化降解壳聚糖的影响

研究了氧气在不同壳聚糖溶液初始质量浓度、pH值、温度、进口压力、空化时间等条件下,对壳聚糖涡流空化降解的影响。结果表明：壳聚糖溶液的初始质量浓度越低涡流空化降解效果越好,当溶液pH值为4.4、温度为70 ℃、进口压力为0.4 MPa、空化时间为3 h时,壳聚糖的特性黏度下降率最高;在不同涡流空化降解条件下,连续通入氧气均可显著促进壳聚糖降解产物特性黏度下降率的提高,在本实验中最大可提高35.36%;氧气对高质量浓度壳聚糖降解的促进作用更显著;氧气的通入减弱了pH值对壳聚糖降解的影响、在反应的初期大大加快了反应速率;降解后的壳聚糖主链结构及官能团基本没发生变化。     

高浓度壳聚糖溶液酶解条件优化

在研究了壳聚糖酶的温度和pH稳定性的基础上,通过在溶解过程中加酶对高浓度壳聚糖溶液酶解条件进行优化,考查了加酶时间及加酶量对8%壳聚糖溶液酶解效率和酶解液粘度的影响,并对优化前后目标溶液中几种壳寡糖的含量进行分析。结果表明:壳聚糖酶在45~55℃及pH4.5~5.5范围内保持稳定;对8%壳聚糖溶液体系,在滴加盐酸浓度达到0.17 mol/L时,加入2 U/g壳聚糖的酶液,当盐酸浓度达到0.48 mol/L时再补加3 U/g壳聚糖的酶液,这种方案可以有效降低体系粘度并保持酶活力;薄层色谱和高效液相色谱分析结果表明,通过以上方式的优化,聚合度2~6的壳寡糖总含量及壳五糖和壳六糖的含量均显著增加(p<0.05),分别达到42.7、5.5和3.9 mg/mL,大大提高了生产效率和降低浓缩成本。     

壳聚糖用于纸张染色

利用壳聚糖对漂白硫酸盐浆进行预处理,分别采用Cartasol Red 2FGN liquid直接染料及Cartasol BlueK-2R liquid阳离子直接染料对纸浆进行染色,研究壳聚糖黏度、用量及pH值对染色效果的影响,同时就壳聚糖与硫酸铝的协同效应进行研究。结果表明,增大壳聚糖黏度和用量可提高直接染料染色色度;黏度对阳离子直接染料染色影响不大,但随着其用量的增加,染色色度先增后降;壳聚糖溶液的pH对两种染料的染色效果影响不大。另外,壳聚糖与硫酸铝在直接染料染色时协同效应明显,但在阳离子直接染料染色时较差。     

OPTIMIZATION OF IMMOBILIZATION PROCESS ON CRAB SHELL CHITOSAN AND ITS APPLICATION IN FOOD PROCESSING

Optimization of immobilization process on crab shell chitosan was carried out. The chitosan purified from the crab shell was used as the matrix for the immobilization of α-galactosidase. The prepared matrix was activated with glutaraldehyde at different concentrations and different time intervals and coupling time was determined. Immobilization of α-galactosidase on crab shell chitosan resulted in 72% immobilization yield. The parameters like the effect of pH, temperature, thermal stability and storage stability were determined. The study revealed that immobilized enzyme shows better thermal and storage stability than the free enzyme. The performance of the free and immobilized α-galactosidase was tested in continuous stirred batch reactor to hydrolyze raffinose family oligosaccharides in soymilk. The oligosaccharide content of the soymilk was reduced by 77% in continuous reaction by immobilized α-galactosidase.

PRACTICAL APPLICATIONS

Chitosan used for the immobilization of α-galactosidase offers several advantages for enzyme immobilization and it contains all characteristic features for use as industrial material. Immobilization of one of the industrial important enzyme α-galactosidase, as it has many potential application in hydrolyzing raffinose series of oligosaccharides. The hydrolyzed soymilk after processing by immobilized α-galactosidase is free from flatus-inducing factors like raffinose and stachyose. It can be used as an alternative means for cow's milk for lactose intolerance, particularly among individuals in developing countries. As chitosan used is from the crustacean waste from the crab shell, the production and utilization of chitosan provides an economical alternative means of crustacean shell waste disposal sought worldwide.     

Simultaneous depolymerization and decolorization of chitosan by ozone treatment

ABSTRACT:  Currently, depolymerization and decolorization of chitosan are achieved by chemical or enzymatic methods, which are time consuming and expensive. Ozone has been shown to be able to degrade macromolecules and remove pigments due to its high oxidation potential. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated. Crawfish chitosan was ozonated in water and acetic acid solution for 0, 5, 10, 15, and 20 min at room temperature with 12 wt% gas. In this study, the effects of ozone treatment on depolymerization and decolorization of chitosan were investigated by measuring the molecular weight, viscosity, and color of chitosan. The color of ozone-treated chitosan was analyzed using a Minolta spectrophotometer. The degree of deacetylation was determined by a colloid titration method. Molecular weight of ozone-treated chitosan in acetic acid solution decreased appreciably as the ozone treatment duration increased. Ozonation for 20 min reduced the molecular weight of the chitosan by 92% (104 kDa) compared to the untreated chitosan (1333 kDa) with a decrease in viscosity of the chitosan solution. Ozonation for 5 min markedly increased the whiteness of chitosan with a molecular weight of 432 kDa; however, further ozonation resulted in development of yellowness. In the case of the ozonation in water, there were no significant differences in the molecular weight and color between ozone-treated chitosans. This study showed that ozone can be used to modify molecular weight and remove pigments of chitosan without chemical use in a shorter time and with less cost.