Shelf life extension of Oncorhynchus aguabonita fillets based on Trachyspermum copticum essential oil nanoemulsion coating during storage at 4°C

This study investigated the effects of Trachyspermum copticum essential oil nanoemulsion (TCEO-NE) coating on chemical, microbial and sensory changes of Oncorhynchus aguabonita fillets during storage at 4 °C. The components of T. copticum EO were identified using gas chromatography-mass spectrometry. TCEO-NE was prepared by ultrasonic method and its properties were determined. Fresh O. aguabonita fillets were immersed in TCEO-NE and stored at 4 °C. Chemical (pH, TVB-N, peroxide and TBARS), microbiological (total aerobic mesophilic bacteria, psychrotrophs, Enterobacteriaceae, lactic acid bacteria and Staphylococcus aureus) and sensory analyses (color, odor and taste) of fish fillets were evaluated on days 0, 2, 4, 6, 8 and 11. Thymol, limonene, and alpha-terpinene were the major compounds in T. copticum EO. The droplet size of TCEO-NE was 127.6 nm and PDI was 0.210. The control group exceeded the peroxide limit on day 6, while TCEO-NE 500.00 and 666.66 did so on day 8. The TBARS value in fish fillets was 0.57 mg MDA/kg on day zero which reached 4.76 mg MDA/kg in the control group and 2.90 mg MDA/kg in TCEO-NE 666.66 after 11 days at 4 °C. Aerobic mesophilic count in the control group exceeded the permissible level on day 6 and, in TCEO-NE 500.00 and 666.66, on day 8, therefore the shelf life of fish fillets was improved by two days. On the grounds of the favorable properties of TCEO-NE and its positive effects on chemical, microbial and sensory changes in fish fillets, it can be used as a natural food additive.