A Box–Behnken design with three variables and three levels
was applied for the determination of deproteinization efficiency
of shrimp shells with enzymatic treatment by B. mojavensis A21
proteases. A21 proteases were found to remove up to 88 ± 5% of
the shell proteins in agreement with optimization using response
surface methodology. The optimal conditions for deproteinization
were: an enzyme/substrate ratio of 7.75 U/mg, a temperature of
60 ◦C and an incubation time of 6 h. Chitin obtained by enzymatic
deproteinization was then converted to chitosan, with a low degree
of acetylation, which was found to exhibit remarkably antibacterial
activities.