Hunter Songy

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.

Gelatin coatings have been shown to successfully slow the oxidation of fresh foods. Furthermore, organic acids have proven effective in the inhibition of bacteria and the extension of product shelf life. The purpose of this study was to observe the effects of gelatin and lactic acid treatment combinations on fresh and previously frozen (thawed) wild-caught shrimp. The samples were separated into four treatment groups: control (C), gelatin coating (G), lactic acid followed by gelatin coating (L), and gelatin infused with lactic acid coating (LG). Half of each group was stored at refrigeration temperature (≤4 °C), while the other half was frozen (≤−18 °C) and thawed for the thawed study. Physical, chemical, and microbiological changes were observed in refrigeration storage for 8 days. Results showed that fresh and thawed shrimp exhibited darkening in color over time. Treatments with lactic acid were more blue than yellow. Treated samples developed less oxidation than the control. Psychrophilic counts for samples L and LG remained below the 7 log CFU/g threshold throughout the study. In fresh shrimp samples, the addition of just a gelatin coating was able to increase shelf life by three days, while the addition of lactic acid successfully lowered microbial counts and extended the shelf life by six days. The freeze–thaw cycle negatively affected the extension of shelf life in the G group.