龙虾头壳制备低聚壳聚糖的研究

Preparation of oligo chitosan from shrimp head shell

以虾仁加工的副产品龙虾头壳为原料,采用酸浸碱煮工艺制备甲壳素,得率为(16.11±0.73)%;浓碱处理脱乙酰基制得壳聚糖,得率为(68.07±1.60)%(相对于甲壳素);选用纤维素酶对壳聚糖进行降解制备低聚壳聚糖。分别研究了加酶量、pH、温度、时间、底物物浓度对壳聚糖降解为低聚壳聚糖的影响。选择0.5%的壳聚糖浓度,通过优化设计试验,确定纤维素酶降解壳聚糖最佳条件为:加酶量8IU/(g底物),pH5.0,温度60℃,时间4h。取最佳工艺条件下降解的低聚壳聚糖,采用乙醇分步沉淀,EP75为(2.36±0.15)%,平均聚合度为9;EP87为(0.85±0.15)%,平均聚合度为7;ES87为(79.84±0.10)%,平均聚合度为5。龙虾头壳制备壳聚糖,纤维素酶降解制成聚合度10以下的低聚壳聚糖,平均得率为8.8%。

Abstract： Shrimp head shell, the by - product of shrimp processing, was used to prepare chitin. The yield of chitin was 16. 11± 0. 73% by acid pickling and alkali cooking method. The yield of chitosan （compared to chitin） was 68.07± 1.60% by concentrated alkali treatment. Then, cellulase was used to degrade chitosan into oligochitosan. The effects of enzyme amount, pH, temperature, reactive time on degradation of chitosan and substrate concentration were studied. The results showed thatthe optimum cellulase depolymerization conditions were： chitosan concentration 0. 5% , the mass of cellulose 8IU/ （ g/substrate）, pH 5.0, temperature 60℃, reaction time 4h. Using ethanol pre- cipitation, the results were： in 75% ethanol precipitation, chitosan yield was 2. 36± 0. 15%, the average degree of polymerization was 9; in 87.5% ethanol precipitation, the yield was0. 85 ±0. 15%, and the average degree of poly- merization was 7 ; in 87. 5% ethanol supematant, the yield was 79. 84± 0. 10%, the average degree of polymerization was 5. The yield of oligochitosan with polymerization less than 10after cellulase degradation was 8. 8%.