Grapefruit Seed Extract and Lemon Essential Oil as Active Agents in Corn Starch–Chitosan Blend Films

Abstract

The effect of lemon essential oil (LEO) and grapefruit seed extract (GSE) addition to starch–chitosan blend films on their functional properties and the associated structural changes were studied. Likewise, the films’ antioxidant properties and antimicrobial activity against some molds and Gram (+) and Gram (−) bacteria was evaluated. Composite active films exhibited a yellowish color, especially in the case of LEO addition. Film microstructure was analyzed by SEM evidencing a good incorporation of GSE to film matrix, while LEO droplets were dispersed in the polymer blend. Oxygen and water vapor barrier properties were not notably modified by the presence of active agents. FTIR analyses revealed that hydrogen bonding occurs in the blend films as the main interaction mechanism between components. Films containing LEO or GSE were less stiff and resistant but more stretchable than the control ones, being this effect concentration dependent. No notable antimicrobial action was observed in the films, which suggest that the required final concentration of active compounds must be fitted considering the minimum inhibitory concentration (MIC) values for a specific microorganism and its release kinetics to the food matrix.