Chitin production by Lactobacillus fermentation of shrimp biowaste in a drum reactor and its chemical conversion to chitosan

Chitin was produced by fermenting shrimp heads and shells with Lactobacillus plantarum 541 in a drum reactor with an internal volume of 3 dm. The crude chitin yield from heads and shells was 4.5 and 13% respectively, comparable to the values obtained by the chemical method. For shrimp heads 83% deproteination and 88% demineralisation and for shrimp shells 66% deproteination and 63% demineralisation were achieved. The liquor obtained in both cases was of good sensory quality with a high content of essential amino acids and therefore with potential to produce protein powder for human consumption. The crude chitin was refined and converted to chitosan using 12.5 M NaOH. The chitosan obtained had a residual ash and protein content below 1%, a solubility of more than 98%, a viscosity in the range 50–400 cP and a degree of deacetylation of 81–84%. The molecular weight was in the range (0.8–1.4) × 106 Da. IR analysis indicated that the chitosan obtained through fermentation was similar to that obtained by the chemical method.