Background/Objectives: Lipid oxidation is a major factor limiting the shelf life and nutritional quality of edible vegetable oils. Enhancing the oxidative stability of extra virgin olive oil (EVOO) through natural antioxidants is of increasing interest to both industry and consumers. This study aimed to evaluate the impact of five plant-derived essential oils (orange, lemon, black pepper, oregano, and rosemary) incorporated at three concentrations (0.5, 1, and 2% w/w) on the oxidative stability, antioxidant capacity, and bioactive compound retention of EVOO. Methods: All fortified EVOO samples were stored at 60 °C for 28 days to simulate accelerated oxidation. A positive control containing 200 ppm of butylated hydroxytoluene (BHT) was included for comparison. Oxidative stability was assessed through peroxide value, TBARS, p-anisidine value, and conjugated dienes/trienes. Tocopherols, carotenoids, and chlorophylls were quantified, while radical scavenging activity was determined using Trolox-equivalent assays. Correlation analyses were performed to explore relationships between essential oil composition and antioxidant performance. Results: Among the tested essential oils, oregano at 2% demonstrated the strongest protective effect, reducing both primary and secondary oxidation products and yielding a Totox value (34.26) close to that of the BHT-enriched control (29.86) after 28 days. Regarding long-term radical scavenging capacity, rosemary at 1% concentration provided the closest activity to BHT (402.89 vs. 536.64 μM Trolox equivalents). Both oregano and rosemary enhanced the preservation of α-tocopherol, likely due to the activity of key constituents such as carvacrol and 1,8-cineole. Conclusions: The incorporation of selected essential oils, particularly oregano and rosemary, can effectively enhance the oxidative stability and antioxidant capacity of EVOO, supporting their potential use as natural alternatives to synthetic antioxidants.
Kalompatsios et al. (Tue,) studied this question.