Antimicrobial activity and physical properties of starch/chitosan film incorporated with lemongrass essential oil and its application

Starch-based composite films incorporated with lemongrass essential oil (LEO) have been successfully made by the casting method. The effect of five types of essential oils (EOs), lemongrass, kaffir lime peel, guava leaf, plai and fingerroot to pathogenic microorganisms showed that LEO had the least minimum inhibitory concentration (MIC) towards E. coli TISTR 512, S. thypimureum TISTR 1470, S. aureus TISTR 746, B. cereus TISTR 035 C. albicans TISTR 5554 and A. niger TISTR 3130 at 1.56 +/- 0.00, 0.65 +/- 0.23, 0.39 +/- 0.00, 0.39 +/- 0.00, 0.52 +/- 0.18 and 0.78 +/- 0.00 mu l mL(-1) respectively. Moreover, the minimum bactericidal concentration (MBC) of all bacteria was different from each species, and the least concentration was LEO. Incorporating LEO to the cassava starch/chitosan film showed the reduction of both tensile strength and elongation at break. Therefore, glycerol with different concentrations was added to get the optimum condition on film properties. Among the different concentrations added, 20% of glycerol resulted in an optimum condition toward physical (water vapor permeability and water solubility) and mechanical properties (tensile strength and elongation at break). The coating system was successfully conducted on chilies and showed a significant value on the total microbial reduction growth compared with the control during 16 days of storage.

Automated summary

Starch-based composite films incorporated with lemongrass essential oil were successfully made by the casting method, showing the best inhibitory effect on various pathogenic microorganisms. The addition of glycerol improved the physical and mechanical properties of the films, and the coating treatment on chilies demonstrated a significant reduction in microbial growth.