combined application of postbiotics and thyme essential oil nanoemulsion for extending rainbow trout fillet shelf life

This research aimed to investigate the effects of postbiotics derived from lactiplantibacillus plantarum (pl) and thymus diagenesis celak essential oil (tdeo) nanoemulsion (eon) on microbial, chemical and sensorial characteristics of rainbow trout fillets. the pl50 with a concentration of 50% w/v of lyophilised pl, eon1.5 containing 1.50% v/v of tdeo, eon3 containing 3% v/v of tdeo and pl50-eons as combined forms of pl50 and eons were sprayed on rainbow trout fillet. total psychrotrophic count (tpc), total mesophilic count (tmc), ph, total volatile base nitrogen (tvb-n), thiobarbituric acid (tba) and sensorial characteristics of control and treatment groups were evaluated during 9 days of storage at 4 °c. shelf life of the control sample was up to 6 days, while at the same day, pl50-eon3 exhibited significantly lower tpc (2.59 log10 cfu/g), tmc (4.87 log10 cfu/g) and tvb-n (23.40 mg/100 g sample). sensory evaluation showed that the treated sample with pl50-eon3 had a higher acceptance than the control sample. the obtained results from pl50-eon3 treated group can be related to the synergistic effect of the pl50 components, including plantarcin and organic acids (1, 2) and eon3 components, such as thymol and carvacrol (3). the principal component analysis showed that eon3 and pl50-eon3 had positive effects on the tba, tmc, tpc, tvb-n, and ph parameters of fillets. in conclusion, pl50-eons prolonged the shelf life of fillets by >3 days based on quality parameters threshold limits. the findings demonstrate the potential of postbiotics in combination with eon to develop a preservative solution in fish products.