Production of chitosan from shrimp shell using ultrasound followed by subcritical water hydrolysis

The interest in shrimp shell valorization has been growing in line with sustainability goals. Therefore, the main objective of this study was to obtain chitosan from shrimp shell using ultrasound followed by subcritical water treatment. Ultrasonication of shells was performed at 600 and 1200 W for 5 min. Then, shells were hydrolyzed at 140-260 C-degrees and 50 bar for 10-60 min followed by demineralization using citric acid, bleaching using hydrogen peroxide and deacetylation using sodium hydroxide solution. The highest deproteination (80.93 %) was obtained by ultrasonication at 1200 W/5 min followed by subcritical water hydrolysis at 260 C-degrees/50 bar/60 min, where the residue with a yield of 10.56 %, whiteness index of 60.42, degree of deacetylation of 64.27 %, relative crystallinity of 32.66 % and similar functional groups to the commercial sample was obtained. These results indicated that the combination of ultrasound with subcritical water is promising to valorize shrimp shell towards production of value-added compounds.