Chitin and derivatives used for biomedical or pharmaceutical applications require a high level of purityand quality that are difficult to achieve. In this study, we propose to optimize the extraction of chitinin order to obtain pure product keeping a structure as close as possible to the native form. Thus, dem-ineralization step was firstly optimized using response surface methodology. In the optimized conditionspredicted by the model, the obtained chitin has an acetylation degree (DA) and a demineralization degree(DM) equal to 99% and 100%, respectively.Then, different microbial and fish crude alkaline proteases were tested for their efficiency in depro-teinization. Crude alkaline proteases giving the highest deproteinization degrees (DP), Bacillus mojavensisA21 and Scorpaena scrofa, were selected for chitin extraction. The obtained DP was 88 ± 2% and 83 ± 1%,respectively.At the end, effect of the use of mixed enzymatic treatment with the two selected crude enzymesand the order of demineralization/deproteinization steps were tested. The results demonstrated thattwo separated steps in enzymatic treatments realized on demineralized sample give the best DP (96%)preserving the DA (99%).