A Natural Solution Against Fish Oil Oxidation: The Antioxidant Effect of Satureja montana Essential Oil

Enhancing Oxidative Stability in Aquaculture Feeds

Abstract

Fish oil, due to its high content of polyunsaturated fatty acids (PUFA), is extremely sensitive to oxidation, which can negatively affect its nutritional quality and shelf life. In this study, the effects of Satureja montana (SMont EO) essential oil on fish oil oxidation were investigated. Within the scope of the experiment, different concentrations (100, 200, 400, 800 ppm) of Satureja montana essential oil were added to fish oils, and the commercial antioxidant BHT (200 ppm) was used as a positive control. The experimental groups were subjected to accelerated oxidation for 96 hours under 55°C temperature, 70% humidity, and 7000 lux illumination. Oxidation levels were determined by measuring peroxide value (PV) and malondialdehyde (MDA), and the obtained data were statistically analyzed using one-way ANOVA and Tukey's test. According to the GC-MS analysis results, Satureja montana essential oil contains the highest amounts of carvacrol (42.62%), γ-terpinene (12.44%), and p-cymene (14.09%). It has been reported in the literature that carvacrol is a strong free radical scavenger, γ-terpinene can prevent lipid peroxidation, and p-cymene plays an important role in combating oxidative stress. According to the peroxide value measurements, it was determined that the group containing 400 ppm Satureja montana oil had the lowest oxidation level. The peroxide value of the 400 ppm dose was determined to be 16.08 meq O₂/kg, which is similar to the commercial antioxidant BHT (25.48 meq O₂/kg). MDA levels were also measured at the lowest level in the 400 ppm essential oil group, but a slight increase was observed at the 800 ppm dose. The results indicate that Satureja montana essential oil is an effective natural antioxidant in preventing fish oil oxidation. It has been determined that a concentration of 400 ppm provides the best oxidative stability. Compared to the commercial antioxidant BHT, Satureja montana essential oil provided a similar level of oxidative protection, therefore it can be considered as an alternative to synthetic antioxidants in aquaculture feeds.