Preparation of Films Based on Reticulated Fish Gelatin Containing Garlic Essential Oil.

Agro-industrial co-products, such as fish gelatin, stand out for their capacity in forming biopolymeric films, being biocompatible and non-toxic; however, its hydrophilicity poses a challenge. Essential oils, rich in bioactives, attract research interest aiming to enhance the protective barrier of films and enable their application in packaging. This study produced films based on cross-linked Nile tilapia skin gelatin, incorporating garlic essential oil. Gelatin obtained through partial collagen hydrolysis from the fish skin and cross-linked with gallic acid had hydroxyproline content of 10.02 g 100 g -1 and gel strength of 287 g, which were consistent with other studies. Oil extraction used supercritical CO 2 as a solvent and ethanol as a cosolvent, following a factorial experimental design, evaluating the extraction temperature (40 degrees C and 70 degrees C) and cosolvent ratio (1:1 and 1:3), with three central points. Extraction was successful, with higher yields on a dry basis at 70 degrees C (88.35 %), using a 1:1 cosolvent ratio. Films incorporated with oil exhibited lower water vapor permeability (WVP) than those with only cross-linked gelatin (1.59 (g m - 1 s - 1 Pa - 1 ) 10 11 ). The film with the most suitable tensile strength (19.07 MPa), elongation (120.91 %), and WVP (1.09 (g m -1 s -1 Pa - 1 ) 10 11 ) properties contained garlic oil extracted at the central point (55 degrees C and 1:2). Thermal analysis indicated increased melting temperatures in films with added oil, suggesting low thermal degradation. These results suggest that garlic oil addition can improve the properties of fish gelatin-based films, making them promising for biodegradable packaging.