Evaluation of Catfish Skin Gelatin-Based Edible Antimicrobial Coating with Lactic Acid and Potassium Sorbate on the Shelf Life and Quality of Fresh Catfish Fillets

Edible coatings derived from fish by-products offer promising, sustainable approaches for seafood preservation. This study evaluated catfish skin gelatin as a carrier for antimicrobial agents to enhance microbiological stability, oxidative stability, and shelf life of fresh catfish fillets during refrigerated storage. Shelf life was defined as the storage period required for microbial and quality parameters to reach spoilage-associated limits. Treatments included control (C), lactic acid (LA), potassium sorbate (PS), gelatin (G), gelatin + LA (G+LA), and gelatin + PS (G+PS). Microbial quality (Aerobic Plate Count, psychrophiles, Pseudomonas spp., yeasts), physicochemical properties (pH, moisture, color), and lipid oxidation (TBARS) were assessed. Based on APC and psychrophiles, gelatin combined with antimicrobials was associated with extended shelf life relative to the control, with G+PS (15 days) and G+LA (12 days) compared to 9 days for untreated fillets, while LA and PS alone showed limited effects. All treatments maintained pH < 7.0, and color changes were minimal except for increased b* in LA treatments. TBARS increased during storage, particularly with LA, but remained below 5 mg MDA/kg. Overall, gelatin-based systems, particularly with PS or LA, offer a cost-effective, sustainable approach to potentially improve refrigerated fish quality while valorizing fish by-products. Further work is needed to optimize formulations and validate results under commercial conditions.