Optimization of Shrimp Shell Waste Deproteinization and Deacetylation for Chitosan Production Using a Fractional Factorial Design (FFD)

Abstract

Chitosan is deacetylated chitin, the second most common polysaccharide after cellulose. The diverse applications of chitosan are directly linked to the properties of the polymer, which vary depending on the extraction process. This study aimed to investigate the factors that influence the deproteinization and deacetylation of chitin and to elucidate their effect on the residual protein level, the level of deacetylation (DD), and the yield of extracted material. The selected responses were studied using a 25-1 fractional factorial design with five factors and two levels of variation. The factors tested were A NaOH concentration, B = reaction time, C temperature, D = Particle size, and E = Solid/Liquid ratio. Using the ANOVA regression equation gives a coefficient of determination R2 = (99.62%, 99.72%, and 99.90%) for the residual protein level, the deacetylation (DD), and yield, respectively, indicating the precision of the predicted model. The minimum of residual proteins,  the maximum deacetylation DD% and yield% reached under those conditions corresponds to the concentration of NaOH (20%,40%), temperature (40°C,129.88°C), reaction time (15.03,60min), particle size of (0.3,01mm) and Solid/Liquid ratio of (1/10.02,1/15 g/ml). After carrying out the validation test, the chitosan obtained presents a yield, ash rate, residual proteins, a DD%, solubility, crystallinity, and a molecular weight of 16.16±0.22, 0.124±0.002, 2.08±0.05%, 87.13±0.16%, 97.02±0.09%, 44.32%, and 107.47±0.44KDa respectively.