Preparation of Chitosan Film for Smart Packaging: The Effects of Base on Deacetylation Process

Abstract

Shrimp waste contains a high content of chitin which is potential to be used as a chitosan’s precursor. Synthesis of chitosan is usually done by deproteination, demineralization, and deacetylation process. Deacetylation of chitin from shrimp waste isolated by autolysis, has been a few reported before. The chemicals involved in autolysis are less harmful and easier to treat before their disposal. Hence, this paper investigates the effect of base type and concentration on the degree of deacetylation of chitosan from chitin isolated by autolysis. Autolysis was carried out by an incubation at pH 2 using sulfuric acid for 10 d. Demineralization was performed by immersion in hydrochloric acid pH 1 for 24 h. The deacetylation of chitin was carried out at 120 °C for 120 min using two different bases, which are NaOH and KOH, respectively. The determination of chitosan’s degree of deacetylation (DD) was carried out using a semi-quantitative method from IR spectra. The use of KOH resulted in the obtained DD of less than 20%, while the NaOH usage produced around 50% of DD. Then, the NaOH was chosen and studied further to obtain a suitable DD for film applications, which is 40 – 99%. The deacetylation of chitosan was carried out by varying NaOH concentration from 60 to 70% (w/v). High concentration of NaOH tends to increase chitosan’s DD and slightly decrease the yield. The optimum concentration of NaOH was obtained at 70% (w/v) producing DD of 53.50±0.83% and yield of 47.66±0.28%. Chitosan synthesized using 70% concentration of NaOH produced a relatively homogeneous thin film. Polyaniline was then introduced to the film to obtain a prototype of smart packaging. This smart packaging was able to detect the pH changes proven by the change of its color.