Development of a Pilot-ecofriendly Process for Chitosan Production from Waste Shrimp Shells

New results are presented on a pilot and ecofriendly process to produce chitosan from waste shrimp shells. The process comprises demineralization with citric acid, enzymatic deproteinization with papain or bromelain to produce chitin and deacetylation to obtain chitosan (yield of 1 kg chitosan/kg shrimp shell, 64% deacetylated, 87.5% deproteinized and 98% demineralized). Shell particles of 1–25 mm were used instead of the shell powder that has been used in many studies. The developed process showed important technical and environmental advantages compared to the conventional process. A 10% increment in chitosan yield was obtained due a lower chitin hydrolysis. The ecofriendly process has 24% lower consumption of water. Residual water from citric acid demineralization does not need to be neutralized and can be re-circulated after the citrate salts recovery. Citrate salts are value-added byproducts for nutritional supplements and are easily recovered due to their low solubilities. Residual water from enzymatic deproteinization does not require neutralization and can be treated easier than water from the conventional process. Dissolved solids could be recovered by evaporation and used as animal feedstock for pink-colored fishes. The use of organic acids and enzymes in chitin extraction, compared to HCl and NaOH, does not require special materials for the reactors, reducing investment costs. Highlights • Ecofriendly process uses citric acid and enzymes instead of HCl and NaOH • 10% increment in chitosan yield was obtained due a lower chitin hydrolysis • Ecofriendly process has a 24% lower consumption of water • Residual water does not need to be neutralized and can be re-used • Citrate salts, proteins and carotenoids are value-added byproducts