Efficacy of stinging nettle extract in combination with ε-polylysine on the quality, safety, and shelf life of rainbow trout fillets

The effects of incorporation of stinging nettle extract (3% and 6%) and ɛ-polylysine (0.1% and 0.2%) on chemical, microbial properties, and stability of rainbow trout fish fillets wrapped in polyethylene bags (in atmosphere condition) and refrigerated for 12 days at 4°C were evaluated. No remarkable differences regarding the chemical composition of rainbow trout fish (protein, moisture, fat, and ash content) resulting from the treatments were noted. The lowest TBARS (thiobarbituric acid reactive substance) and the highest phenolic compounds were noted in samples treated with 6% SNE + 0.2% ɛ-PL on day 12, while the highest inhibitory effects against the growth of TVC, psychrotrophic bacteria, coliform, yeast, and molds corresponded to samples treated with 6% SNE (T4 and T5) at day 12. During the storage, the samples' TVB-N (total volatile base nitrogen) increased, whereas the total phenolic content of the rainbow trout samples declined. The rainbow trout samples treated with 6% SNE + 0.2% ɛ-PL had the highest amount of redness and the lowest TVB-N values. Therefore, these natural ingredients could be used to maintain rainbow trout meat quality and shelf life.