Preparation of Fungal Chitin and Chitosan from Shiitake Stipes

Crude fungal chitin was prepared from shiitake stipes as the raw material using alkaline treatment followed by three various decolorization methods. Yields of crude shiitake chitins were 25.08–36.72% and in the descending order of chitins B＞A＞C. The crude fiber content of chitin C was higher than those of stipes and chitins A and B. Chitin C obtained by decolorization with potassium permanganate showed the best color. Using chitin C as raw material, chitosan C was obtained with higher yields. At higher ratios of chitin to sodium hydroxide of 1:9, 1:12, and 1:15, no difference in the yields was found on the basis of raw material. For the yields, better conditions were at ratios of 1:9, 1:12, and 1:15 for 60 min, and the yields were 14.14-19.14% for chitosan B and 19.54-23.69% for chitosan C. For degrees of N-deacetylation (DD), better conditions were at ratios of 1:5 and 1:15 for 120 min and the DD was 95.39-98.21%. The proposed conditions for N-deacetylation of fungal chitin would be at a ratio of 1:12 for 60min.