Evaluation of effects of nanoemulsion based on herb essential oils (rosemary, laurel, thyme and sage) on sensory, chemical and microbiological quality of rainbow trout (Oncorhynchus mykiss) fillets during ice storage

- The oil-in-water nanoemulsions based on herb essential oils for the quality of rainbow trout was developed.
- Treatment with nanoemulsions reduced the values of chemical markers of deterioration.
- Nanoemulsion prolonged the shelf life and improved the quality of fish.
- Thyme and rosemary are recommended for nanoemulsion as a preservative for fish.

Antimicrobial and antioxidant effects of nanoemulsions containing herb oils (rosemary, laurel, thyme and sage) on the quality of rainbow trout were investigated. Fish fillets were immersed for 3 min in the nanoemulsions prepared with different oils. During 24 days of storage, sensory (raw and cooked), chemical (TBA (thiobarbituric acid), pH, TVB-N (total volatile basic nitrogen), PV (peroxide value), FFA (free fatty acids)) and microbiological quality (total mesophilic aerobic and psychrophilic aerobic bacteria, Enterobacteriaceae count) of rainbow trout fillets in ice at 2 ± 2 °C were carried out. Nanoemulsions of essential oils enhanced organoleptic quality of rainbow trout. Shelf life of rainbow trout was found as 14 days for the control, 17 days for the treatment groups. The use of nanoemulsions based on all essential oils reduced the values of the biochemical parameters and slowed down the growth of bacteria. TVB-N values were lower in all samples than limit value. FFA and PV developed at a slower rate in the treated groups, especially in the rosemary group. The lowest bacterial numbers were obtained from rosemary followed by thyme group. Among the essential oils, it can be concluded that rosemary and thyme can be recommended for nanoemulsion as a preservative for fish fillets.