蚕蛹甲壳素的脱色方法与机理探讨

Decolorization of Chitin from Silkworm Chrysalis

研究了从粗甲壳素 (分离蚕蛹蛋白质后的残渣 )中提取蚕蛹甲壳素的工艺条件 ,探索了H2 O2 氧化脱色方法。实验结果表明 ,在 70℃的水浴中 ,按照m(蚕蛹渣 )∶m(5 %氢氧化钠 ) =30∶80的质量比处理 2h ,可脱净残余蛋白 ,得到黑褐色的粗蚕蛹甲壳素。用H2 O2 脱色漂白 ,工艺条件为 :6 5～ 70℃ ,pH值为 8 5± 0 5 ,时间 5h ,m (蚕蛹渣 )∶m(30 %H2 O2 ) =5 0∶130。所得甲壳素白度为 30 % ,收率为 2 5 %。双氧水脱除蚕蛹甲壳素颜色的机理可能是H2 O2 分解的O2 -2 作用于铁硫蛋白与细胞色素复合物体系中的硫 ,将体系中半胱氨酸硫氧化成亚砜 ,使得色蛋白与甲壳素相连的键断开 ,从而使色素从甲壳素上分离下来。

The colored chitin has been isolated from silkworm chrysalis with protein being extracted off with NaOH solution. The decolorization of the colored silkworm chrysalis chitin was performed by aq. H 2O 2 solution treatment. The conditions for taking off protein are as follows:m(5%NaOH)∶m(silkworm chrysalis residue)=80∶30, 70 ℃ and 2 h. The calcium containg salts can be taken off completely with 3%HCl in conditions of 2 h, 25 ℃ and m(3%HCl)∶m(silkworm chrysalis residue)=8∶3. The colored crude chitin without protein and salts can be decolored by H 2O 2 treatment in conditions of 65～70 ℃, pH 8.5±0.5, 5 h and m(30%H 2O 2)∶m(silkworm chrysalis residue)=130∶50. The yield of white chitin is 25% with whiteness above 30%. It suggested that H 2O 2 oxidizes the sulfur of cysteine present in the system of iron-sulfur center and and the cytochromes and changes it into sulfoxides, causing the chemical bond between the chromoprotein and the chitin to be broken and chromoprotein to be separated.