Thermokinetic Parameters and Shelf-Life Prediction of Sacha Inchi Oil Stabilized with Essential Oils

Sacha inchi oil is a highly unsaturated edible oil with considerable nutritional value but high susceptibility to oxidative deterioration. This study evaluated the effects of matico (Piper aduncum L.), real lemon (Citrus limon (L.) Burm. f.), and spearmint (Mentha spicata L.) essential oils (EOs) on the thermokinetic behavior, oxidative stability, and estimated shelf-life of sacha inchi oil. EOs were incorporated at 0.1%, 0.3%, and 0.5% (v v−1), and oxidative stability was evaluated by Rancimat at 90, 100, and 110 °C after 0, 7, 15, 30, and 90 days of storage. Activation energy (Ea), temperature coefficient (Q10), and changes in activation enthalpy (ΔH++), activation entropy (ΔS++), and Gibbs free energy (ΔG++) were calculated from the oxidative stability index (OSI) and used to estimate the shelf-life of the oil at storage temperature (T = 25 °C). EO type, EO concentration, and storage time had significant effects on the estimated shelf-life of sacha inchi oil (p < 0.05). Spearmint showed the most persistent protective effect, with the highest OSI values and an estimated shelf-life of approximately 350 days, whereas real lemon exhibited a more consistent protective effect throughout storage. EOs increased the activation energy (Ea) from 113.22 kJ mol−1 in the control to approximately 120 kJ mol−1 in the treated samples, indicating a higher apparent energetic barrier to oxidation. The temperature coefficient (Q10) increased from 2.665 to approximately 2.86, while the activation enthalpy (ΔH++) and Gibbs free energy (ΔG++) also increased in EO-treated samples, and the positive activation entropy (ΔS++) values indicated greater molecular disorder in the transition state. Overall, essential oils modulated the thermokinetic behavior of sacha inchi oil, increasing the apparent energetic barrier to oxidation and extending its predicted shelf-life, highlighting their potential as natural systems for stabilizing highly unsaturated edible oils.