脱乙酰甲壳质制备工艺的改进

背景:采用传统工艺制备脱乙酰甲壳质,其脱乙酰度和纯度不高、相对分子质量较低,使其应用受到一定影响。目的:改进从虾蛄壳中提取制备脱乙酰甲壳质的传统工艺。设计:对比观察。单位:山东省生物药物研究院。材料:实验于2003-02/2004-01在山东省生物药物研究院的山东省生物药物重点实验室完成。实验用仪器:Mettler AE240电子分析天平(梅特勒-托利多仪器有限公司);ZK-40AB电热真空干燥箱(上海树立仪器仪表有限公司)。实验用材料:虾蛄(济南市水产市场)。方法:①脱乙酰甲壳质传统的提取制备工艺是虾、蟹等甲壳在常温下经稀酸脱钙、稀碱高温脱蛋白质得到甲壳质,再经强氧化剂脱色、浓碱高温脱乙酰基得到脱乙酰甲壳质。②改进的工艺制备过程是虾蛄壳在常温下经稀酸脱钙、脱色,常温下稀碱脱蛋白质、脱色,再经稀酸二次脱钙、脱色得到甲壳质。所得甲壳质在浓碱55～65℃下脱乙酰基、脱色,得到脱乙酰甲壳质粗品。将脱乙酰甲壳质粗品溶于一定量稀酸中,过滤,取滤液,再用稀碱沉淀,过滤,弃去溶液,收集沉淀物,水洗,烘干即得脱乙酰甲壳质精品。主要观察指标:改进工艺与传统工艺的比较,不同工艺所得脱乙酰甲壳质的颜色、在稀酸中的溶解性、收率、脱乙酰度和动力黏度。结果:①工艺比较:改进工艺相对传统工艺整体反应条件温和,脱蛋白质条件为常温,不需单独脱色过程,脱乙酰基条件相对低温,有精制过程。②脱乙酰甲壳质各项检测指标:改进工艺所得脱乙酰甲壳质收率略低于传统工艺(分别为15%,17%),脱乙酰度、动力黏度均高于传统工艺(分别为>95%,<70%;>120mPa·s,<80mPa·s),脱乙酰甲壳质外观为白色或类白色,好于传统工艺(黄色或灰色),脱乙酰甲壳质易溶于稀酸,溶解性好于传统工艺(部分不溶于稀酸)。结论:改进工艺较传统工艺更简单,反应条件更温和,且所得脱乙酰甲壳质质量明显提高。

Improved technique for preparation of deacetylated chitin

BACKGROUND: The application of deacetylated chitin (chitosan, DC) prepared by traditional technique was limited because of its lower degree of deacetylation, impurity and relative lower molecular mass.OBJECTIVE: To improve the traditional technique for extraction and preparation of DC from the rustae f oratosquila oratoria.DESIGN: Contrasting observation.SETTING: Shandong Institute of Biopharmaceutics.MATERIALS: The experiment was carried out in the Shandong Key Laboratory for iopharmaceutics, Shandong Institute of Biopharmaceutics from February 2003 to January 2004. Experimental nstrument: Mettler AE240 electronic analytical balance and ZK-40AB electrothermal vacuum drying oven were rovided by Mettler-Toledo Instruments Co., Ltd. And ShangHai Shuli Instruments Co.,Ltd., respectively. Xperimental materials: oratosquila oratoria was purchased from Jinan aquatic products market.METHODS: ①C as traditionally prepared from chitin by decoloring with strong oxidant and deacetylating with concentrated alkaline liquor under high temperature. Chitin was extracted from crustae of shrimp and crab fter decalcification with diluted acid and deproteinization with diluted base. ②The improved preparation echnique: The crustae of oratosquila oratoria was decalcificated and decolorized with diluted acid, and as deproteinized and decolorized with diluted base at room temperature, and then the chitin was obtained fter the second decalcification and decolorization with diluted acid. The crude DC was obtained from hitin after deacetylation and decolorization with concentrated ase at 55-65 ℃. The crude DC was issolved n diluted acid and filtered. The filtrate was collected, precipitated with dilute base. After filtering, he sediments were retained, washed with water and dried. Then pure DC was obtained.MAIN OUTCOME MEASURES: he comparison between improved technique and traditional technique; Color, dissolvability in diluted cid, ield, degree of deacetylation and dynamic viscosity of DC prepared by different techniques.RESULTS: ①echnique comparison: Compared with traditional technique, the reaction of improved preparation technique as milder, and the deproteinization was at room temperature; it did not need an isolated decolorization;deacetylation was at low temperature, and had a refine process. ②Detection indexes of DC: he yield of DC prepared by improved technique was little lower than that by traditional technique (15%, 7% respectively). The degree of deacetylation and dynamic viscosity were both higher than those by raditional technique (＞ 95%,＜ 70%; ＞ 120mPa·s,＜ 80 mPa·s , respectively). The color was white or lmost white, which was better than that by traditional technique (yellow or gray). The DC could ompletely issolve in dilute acid, and the dissolvability was better than that by traditional technique (dissolved artly in dilute acid).CONCLUSION: Compared with the traditional technique, the improved technique was mpler and the reaction conditions were milder. And also the quality of obtained DC was obviously improved.