BACKGROUNDSeveral techniques have been proposed to recover chitin from shrimp waste using large amounts of freshwater and chemicals. The standard chemical recovery of chitin was first compared by replacing fresh water with seawater. In addition, a biotechnological process with Bacillus subtilis (B1) and Bacillus licheniformis (B2) using seawater during all steps of chitin extraction was studied. RESULTSThe demineralization rate (DM) was statistically significant when using seawater (P=0.000020) and chemical recovery in comparison with deproteinization (DP). Increasing HCl concentration (from 1 to 1.28 mol L-1) and reaction time (from 60 to 90 min) resulted in DM similar to fresh water (P>0.05). Highest DP rates were obtained with crude protease (B1; DP approximate to 74%) and (B2: DP approximate to 84%), when fermentation was carried out for 24 h at an enzyme/substrate ratio of 2. Maximum DP was reached (approximate to 79% for B1 and approximate to 82% for B2) after 15 days, while DM ranged between 55 and 60%. CONCLUSIONCombined enzymatic DP (with B2) followed by a chemical DM process was used to produce chitin (DP approximate to 84%, DM approximate to 94%) which, on transformation to chitosan, showed a degree of deacetylation equivalent to approximate to 71%. This combined approach using seawater could transform crustacean waste into chitin products of commercial value. (c) 2015 Society of Chemical Industry