Enhancing Arbequina and Arbosana Olive Oils with Koroneiki Fruits and Leaves

This study examined the physicochemical properties, bioactive compounds, and organoleptic characteristics of olive oils from the cultivars Koroneiki, Arbosana, and Arbequina. Arbequina, a commonly cultivated olive variety, had oleic acid content (C18:1) below the International Olive Council (IOC) limit of 55-83% and lower stability due to its low phenolic composition. In contrast, Koroneiki is known for its high oleic acid content, natural antioxidants, and superior oxidative stability compared to Arbosana and Arbequina oils. The study involved processing fruit mixtures and incorporating Koroneiki olive leaves during oil extraction to evaluate various parameters such as physicochemical properties, fatty acid composition, bioactive components, oxidative stability, phenolic compounds, and organoleptic characteristics. Mixing fruits, especially for Arbequina varieties, enhanced the low C18:1 content to meet IOC standards and improved their oxidative stability. The oxidative stability increased by 37.55% and 40.37% when Koroneiki was mixed with Arbosana or Arbequina at a 50:50 ratio, respectively. Furthermore, adding Koroneiki olive leaves at 1% and 3% to a mixture of Koroneiki and Arbequina increased oxidative stability on rancimat at 110°C by 2.02% and 4.66%, respectively, while for Arbosana, it increased by 4.7% and 26.56%. The analysis identified eighteen phenolic compounds in all olive oil samples, with oleuropein, hydroxytyrosol, phenolic alcohols, and phenolic acids being the major compounds. The results suggested that processing fruit mixtures of different cultivars can enhance the quality of olive oil, offering opportunities to adjust antioxidant content, fatty acid composition, color, nutraceutical compounds, and organoleptic properties. Additionally, incorporating olive leaves during oil extraction can yield olive oil with higher antioxidant levels.