Optimizing Bioactive Profiles in Kolovi Olive Oils: Impact of Destoning, Harvest Timing, and Postharvest Factors on Phenolic, Tocopherol, Lutein, and Squalene Content

Extra virgin olive oil (EVOO) is a key component of the Mediterranean diet, valued for its bioactive constituents and associated health benefits. This study evaluated the influence of four agronomic and processing factors-harvest month, destoning, fruit washing, and bottling delay-on the chemical composition of Kolovi EVOOs from the PGI Lesvos region. A total of 34 oils were produced under standardized conditions and analyzed for phenolic compounds, tocopherols, pigments, and squalene using UPLC-QTOF-MS and HPLC-DAD. The oils were characterized by consistently high nutritional quality, with most samples fulfilling EFSA health claim thresholds for hydroxytyrosol, tyrosol and its derivatives, and α-tocopherol. Harvest month was the most influential parameter: early harvested oils (October) contained significantly higher levels of phenolics, α-tocopherol, and lutein, whereas later harvests (November) were richer in squalene. Destoning produced modest changes, with slightly higher phenolics in non-destoned oils and reduced lipophilic antioxidants in destoned samples. Fruit washing selectively decreased hydrophilic phenolics, while lipophilic compounds were largely unaffected. Bottling delays of up to 48 h under protective conditions had negligible effects on composition, aside from minor increases in specific phenolic derivatives. These findings suggest that early harvesting and careful consideration of destoning are the most effective strategies for supporting the antioxidant profile of Kolovi EVOOs, while other practices can be adjusted with limited impact on quality.