Effects of nano-chitosan coatings incorporating with free/nano-encapsulated essential oil of Golpar (Heracleum persicum L.) on quality characteristics and safety of rainbow trout (Oncorhynchus mykiss)

This study investigated the effect of nano-chitosan coating containing free/nano forms of Heracleum persicum L. essential oil (HPEO) on microbial, chemical and sensory properties of rainbow trout (Oncorhynchus mykiss) at 4 °C during storage. In this study, nanoliposomes were prepared using different soy lecithin/cholesterol ratios (30:30, 40:20, 50:10 and 60:0) and sonication-hydration techniques with sizes of 78.70-123 nm. Liposome with a ratio of 50:10 had the greatest EE%. The zeta potantial was between -5.62 ± 0.28 to -3.71 ± 0.31 mV. The index of polydispersity and encapsulation efficiency (EE) were 0.452-0.481 and 51.93-68.13 %, respectively. Based on the results of microbiological and chemical analyses, samples treated with with nanochitosan/nano essential oil (NCS-NEO) had a better effect at the end of the study than other samples (NCS-EO, NCS and control). For NCS-NEO treatment at the end of storage time, analysis the value of total volatile basic nitrogen (TVB-N), pH, thiobarbituric acid reactive substances (TBARs) and peroxide value (PV) were, 27.95 (mg/100 g), 6.9, 0.37 (mEq/kg), 5.13 (mg MDA/kg), respectively, and the total pseudomonads count (TPC), total viable counts (TVC) and lactic acid bacteria (LAB) were, 8, 6.8, and 6.5 CFU/g, respectively. Further, the NCS-NEO treatment (at the end of study) achieved the highest sensory characteristics. HPEO encapsulation decreases diffusion rates, so improving activity of antioxidant and antimicrobial, and characteristics of sensory. This study suggested that coating nano forms of HPEO with NCS could be used to enhance shelf life of rainbow trout fish.