Preparation and properties of biodegradable stearic acid-modified gelatin films

Gelatin was modified by various amounts of stearic acid using different reaction times in aqueous media at 60 °C and pH of 5.5. By casting the modified gelatin solutions, slightly yellow films were formed. It was found that all modified gelatin films had longer drying time, lower tensile strength, lower % moisture absorption, and better biodegradability than unmodified ones. Their oil resistance was comparable. It was also found that the amount of stearic acid and the reaction time significantly affected these properties. As the amount of stearic acid increased, the films exhibited longer drying time, lower tensile strength and lower moisture absorption. With increasing the reaction time, the films exhibited shorter drying time, higher tensile strength and lower moisture absorption. The results suggest that the film prepared from 15% stearic acid-modified gelatin using the reaction time of 8 h had highest potential for applications in environmental friendly packaging.