Improvement of Oxidative Stability and Antioxidative Capacity of Virgin Olive Oil by Flash Thermal Pretreatment – Optimization Process

Flash thermal pretreatment (FTT) is a promising technique for enhancing virgin olive oil (VOO) yield and quality. This study investigated the effects of FTT, both cooling (15 – 25 °C) and heating (30 – 40 °C), on oil yield, phenolics, tocopherols, fatty acid composition, oxidative stability (OSI), antioxidant capacity (AC), and volatile composition in VOOs from three Croatian varieties: Istarska Bjelica, Levantinka, and Oblica. A full factorial experimental design was used with two independent variables: treatment temperature and olive variety. Olive pastes were treated after crushing and before malaxation. Data were evaluated using two-way ANOVA, partial least squares (PLS) regression, and response surface methodology (RSM). Istarska Bjelica showed the highest OSI improvement (+16 %) linked to elevated phenolics and α-tocopherol, and the largest yield increase (+8.1 % at 25 °C). Levantinka exhibited moderate responses, with slight OSI and AC declines and enrichment in lipoxygenase (LOX)-derived volatiles. Oblica was most sensitive to heating, showing OSI and AC reductions (up to 28 %), despite increased oleocanthal, olacein and LOX volatiles. RSM identified optimal FTT temperatures for each variety: 18.9 °C (Istarska Bjelica), 15.4 °C (Levantinka), and 15.5 °C (Oblica). These findings support variety-specific FTT as an effective strategy to improve VOO functional and sensory quality.