Chitosan-starch solution as an antibacterial dip for fresh strawberries

Abstract

Biodegradable films such as chitosan film is fast becoming a popular and effective packaging material for food purposes due to its combined antimicrobial and environmentally friendly properties. Meanwhile, non-antimicrobial biodegradable starch based film has also received great attention in the food packaging sector owing to its wide availability and low cost. In its combined form, chitosan-starch based film is seen as a potential candidate for future low cost and antimicrobial food packaging materials. In the first part of this study, the antimicrobial activity of chitosan broth samples were determined against Escherichia coli (Gram negative) and Lactobacillus plantarum (Gram positive). Trends of inhibition on bacterial growth were confirmed using viable cell count at various chitosan concentrations. Results showed that there is no growth of Lb. plantarum on broth sample containing more than 0.05% (w/v) chitosan while growth of E. coli was minimal (1.6 × 106 CFU/mL) in broth containing more than 0.25% (w/v) chitosan which suggest that chitosan showed stronger inhibition against Lb. plantarum than E. coli. Second part of the study involved preparation of chitosan-starch solution for coating fresh strawberries at chitosan concentrations of 0.05% (w/v) and 0.25% (w/v). Results showed that lactic acid bacteria growth was not present on strawberries coated with 0.05% (w/v) chitosan-starch film during 14 days of storage at 8 °C. However, fungal growth was observed on strawberries coated with 0.25% (w/v) chitosan-starch film at the same storage condition.