Valuable Nutrients, Aroma Profile, and Functional Bioactives Extracted by Eco-Friendly Extraction Techniques from Wild Olive Fruits (Olea europaea L. var. sylvestris)

Abstract

Wild olive tree, or oleaster (var. sylvestris), native to the Mediterranean region, is considered a traditional source of healthy food. Wild olive fruit (WOF) exhibits several biological properties associated with its chemical composition. Although Greece has important olive genetic resources, including oleaster populations, limited information is available on the chemical characterization of WOF. Therefore, the present investigation was undertaken to study the nutritional, bioactive (phenolics, tocopherols, and pigments), volatile profile, and antioxidant properties of WOF collected from Greece. Moreover, eco-friendly processes, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and accelerated solvent extraction (ASE), were applied to obtain oleuropein-rich extracts from WOF. Evaluation of phenolic composition in WOF extracts was carried out by LC-DAD-ESI-MS, while antioxidant activity was evaluated by applying DPPH, ABTS, and FRAP methods. Our outcomes show that Greek WOF is rich in oleic acid (71.55%), total phenolics (64.89 mg GAE/g dw), tocopherols (107.05 mg/kg dw), and carotenoids (85.90 mg/kg dw). Oleuropein (72.03 mg/g dw) was the main phenolic compound in the WOF extracts. Also, the WOF was characterized by an increased level of volatile compounds, mainly terpenoids (46.73%). UAE was more efficient than MAE and ASE for recovering oleuropein-rich extracts with high antioxidant activity. These results emphasized the high potential of WOF as an alternative bioactive ingredient for use in the food industry.