were soaked in 3% HCl for a period of one night to separate minerals and baked at a temperature was 60 °C soaked in 5% NaOH to separate protein, soaked in 5% KMnO4 to separate pigment and fatty acid. Then, the pure chitin was soaked in 50% NaOH at 100 °C in order to separate acetyl group and adjust the pH neutral to chitosan.
เป็นเวลาหนึ่งคืน