Study on extraction of chitin from silkworm chrysalis residue and preparation of chitosan

The silkworm chrysalis residue,in which the oil and protein had been extracted in former processing,was used as raw material to abstract the chitin and farther more to produce chitosan by deacetylation.The optimum conditions for chitosan were investigated and the qualities of products were analysed.The results showed that the degree of deacetylation of the chitosan produced with the method of intermittent type treatment was higher than that with the method of continuous processing.The optimum condition for higher quality chitosan was NaOH solution concentration 50%,processing time 14h,treatment temperature 95℃and the proportion of chitin and NaOH solution 1:25(m:v).Renewed the NaOH solution every 2h,then washed the chitosan to neutral and repeated this work 7 times.The chitosan product was white powder with 80.61%degree of deacetylation,245mPa·s viscosity,56.38%yield,7.68%moisture content and 0.40%ashy substance.The quality indexes of chitin and chitosan were in conformity with the relevant corporate standards.The method in this paper was practical and feasible.