An Innovative Methods for Preserving Tilapia (Oreochromis niloticus) Fish Fillets: Gamma Irradiation with Bioactive Gelatin Coatings

The main issues with seafood marketing and distribution are its high perishability, which is mostly caused by infection from harmful bacteria and spoiling. Using one or more treatments to reduce, destroy, or inhibit microbial contamination may result in effective preservation techniques. Utilizing fish like tilapia to make nutritious fillets and other waste products with economic and nutritional value is a promising industry for Egypt and the rest of the globe. Processing tilapia could yield significant quantities of by-products each year. This study examined the effects of low-dose gamma-irradiation and an edible coating made of bioactive gelatin that was derived from the skin of Nile tilapia (Oreochromis niloticus) on the chemical, microbiological, and sensory qualities of tilapia fillets that were kept at 4 ± 1 °C. Gelatin from tilapia skin was removed and combined with essential oils of cumin, garlic, and chitosan to create a 6% (w/v) coating. Fillets were submerged in the coating solution, drained, and then wrapped before being exposed to γ-irradiation at 0, 1, 2, or 3 kGy. Samples were examined for total volatile basic nitrogen (TVB-N), trimethylamine-nitrogen (TMA-N), thiobarbituric acid (TBA), pH, total bacterial counts (TBC), mold and yeast, psychrophilic bacteria, Staphylococcus aureus, Escherichia coli, and sensory characteristics (texture, appearance, and odor) at 0, 4, 8, 12, 16, 20, and 24 days. The findings demonstrated that by day 12, the untreated control fillets had achieved spoiling limits (TVB-N ≥ 35 mg/100 g; TMA-N ≥ 10 mg/100 g; TBA ≥ 4.5 mg MDA/kg; TBC ≥ 10⁶ CFU/g). However, γ-irradiation at 1, 2, and 3 kGy did not affect sensory scores (staying above 7 on a 9-point hedonic scale), extending the chemical and microbiological acceptability to days 16, 20, and 24, respectively. The 3 kGy treatment produced the optimum pH and lipid-oxidation levels throughout storage and the largest reduction in microbial loads, making psychrophilic bacteria, Staphylococcus aureus, and E. coli undetectable right after treatment. It could be concluded that using the dose of 3 kGy gamma-irradiation treatment in conjunction with a tilapia-skin gelatin bioactive coating (6 %) provides a promising method to lower post-harvest losses in aquaculture processing by successfully extending the refrigerated shelf life of tilapia fillets up to 24 days while maintaining their chemical integrity and sensory quality.