Lactiplantibacillus plantarum postbiotics and thyme essential oil nanoemulsion-based edible spray: An innovative approach to extending shelf life of rainbow trout fillets

This study aimed to investigate the effects of postbiotics from Lactiplantibacillus plantarum (PL) and Thymus daenensis Celak essential oil (TDEO) nanoemulsion (EON) on the microbial, chemical, and sensorial characteristics of rainbow trout fillets. PL₅₀ (50% w/v of PL), EON_1.5 (1.5% v/v TDEO), EON₃ (3% v/v TDEO), and PL₅₀-EON (combined forms of PL₅₀ and EON at two concentrations) were applied as treatments. Total psychrotrophic count (TPC), total mesophilic count (TMC), pH, total volatile base nitrogen (TVB-N), thiobarbituric acid (TBA), and sensorial characteristics of the control and treatment groups were evaluated during nine days of storage at 4 °C. The shelf life of control sample was up to 6 days, while on the same day, PL₅₀-EON₃ exhibited significantly lower TPC (2.59 log₁₀ CFU/g), TMC (4.87 log₁₀ CFU/g), and TVB-N value (23.40 mg/100 g). Sensory evaluation showed that sample with PL₅₀-EON₃ had higher acceptance than the control. Principal component analysis revealed that EON₃ and PL₅₀-EON₃ had positive effects on the quality parameters of the fillets. In conclusion, PL₅₀-EON prolonged the shelf life of fillets by more than 3 days based on microbial, chemical, and sensorial threshold limits. These findings demonstrate the potential of PL and TDEO to develop a preservative solution for fish.