Composite Films from Steam-exploded Gelatin and Thyme Essential Oil: Production, Characterization and Application as Coatings

In this work, the production and characterization of composite films were performed using gelatin extracted after pretreatment by steam explosion at temperatures of 120 oC (GEL120) and 130 oC (GEL130) for 10 min, with and without the addition of Thyme Essential Oil at 0.78% (v/v), employing the casting method. The film-forming solutions were also applied as coatings for refrigerated chicken fillets, and a shelf-life analysis was conducted over 15 days. For comparison, commercial gelatin was used at all stages of production, characterization, and application. In in vitro tests, thyme essential oil exhibited antimicrobial potential against five foodborne pathogens. Due to their distinct physicochemical characteristics, the GEL130 films demonstrated higher tensile strength (7.23 MPa) and lower solubility (76.45%) compared to GEL120. The impact of thyme essential oil addition on the film properties varied depending on the type of gelatin used. The coated chicken fillets showed lower weight loss and pH; however, no significant reduction was observed for Enterobacteriaceae and aerobic mesophilic bacteria compared to the uncoated samples under refrigeration. These findings were promising for understanding the effect of incorporating thyme essential oil into films from gelatins with different characteristics. Additionally, further research is needed to enhance the application of coatings in food matrices.