Effect of Lemon Oil Nanoemulsion and Heat Treatment on Physical Properties and Lipid Quality Parameters of Fish Meat During Storage

In this study, raw and steamed fish (SF) (Oncorhynchus mykiss) samples treated with lemon oil nanoemulsion (LON) were examined. Four groups were designated: raw fish (RF), raw fish treated with LON (RFL), SF, and steamed fish treated with LON (SFL). Changes in the physical properties and lipid quality parameters of fish samples were monitored over 30 days of storage at 4 degrees C +/- 2 degrees C following vacuum packing. The dl-limonene compound, a major component of lemon oil, was detected at a concentration of 75.49%. The LON exhibited a zeta size (ZS) of 197.067 nm, a polydispersity index (PDI) of 0.217, and a zeta potential (ZP) of -3.56 mV. Regarding color characteristics, L* whiteness value, -a greenishness, and +b yellowness values of the nanoemulsion showed a decrease by the end of storage. In all sample groups, except for the L* value in the SFL group, a general trend was observed in which L* increased, a* decreased, and b* increased compared to Day 0 at the end of storage. During storage, thiobarbituric acid reactive substance (TBARS) and free fatty acid (FFA) values remained within acceptable limits for consumption across all groups throughout storage. In conclusion, the application of LON without heat treatment had a positive effect on pH levels. Conversely, when applied to heat-treated fish meat, the nanoemulsion improved the L* value, TBARS, FFA, and overall lipid quality parameters, with the exception of polyene index (PI).Practical applications: Essential lemon oil possesses sensory, antioxidant, and antimicrobial properties. From a sensory perspective, the practical use of freshly squeezed lemon juice on fish meat is widely preferred by consumers. Inspired by this culinary practice, the effects of lemon oil nanoemulsion at a nanoscale on certain quality characteristics of both raw and thermally treated fish meat were investigated. In thermally treated fish meat, the lemon oil nanoemulsion positively influenced color parameters, notably enhancing the brightness (L*) value, as well as markedly improving overall lipid quality indicators. Conversely, the thermal treatment itself adversely affected the pH values of fish meat. Considering lipid quality preservation throughout storage, it is recommended that thermal treatment be applied prior to the incorporation of lemon oil nanoemulsion, ensuring optimal results in both shelf-life and product appeal.