The invention relates to a method for extracting chitin by enzyme and converting it into chitosan. The method of extracting rag includes four steps: grinding of dried protease and inhibition of enzyme.Non mineralized and dry Protein dissolution by the invention includes double digestion by continuous addition and separation of blue crab alkaline protease (5 U / mg protein； 50 ° C； pH 8.0； 3 h) and 10 U / mg protein of Bacillus safensis alkaline preparation. During the 3-hour demineralization process, three 0.55 M HCl baths were used, each bath was 30 minutes, at 4 ° C. 19.06 ± 1.65% of the yield and 92.0% of the desulfurization, demineralization and acetylation degree were extracted from the shell protein.100% and 97%. Crab shell candyThe degree of acetylation was 10%The invention is prepared by using NaOH 12,5 n, 4 hours and 140 ℃ ndsacetine, and also discloses some functions and biological activities of the chitosan obtained. The functional properties of chitosan were estimated to be 221 CP, 100%64.46% and 516.90%As for viscositysolubilityWater retention and oil retention part Interestingly, the alkaline catalyst has significant antioxidant activity, including stabilization of DPH and hydroxyl groups, inhibition of carotene bleaching and metal chelation (%)Page: 1Page: 15 mg / ml respectively. The invention also describes the antibacterial potential of blue crab shell sugar. BCC has a positive interest in all bacterial and fungal strains. The invention also describes the potential of BCC in preventing and eliminating microbial membranes. Chitosan showed excellent anti adhesion activity, including all tested strains even at very low concentrations.The invention also discloses the application of chitosan in the preparation of active biofilm, which is added by carotene from the same species. Key words: "blue crab；ShiaChitosanEnzyme inhibitionFunctional properties； antioxidant and antibacterial activity； anti adhesion potential.Inscrite dans le cadre de la valorisatio
