β-cyclodextrin enhanced ultrasound-assisted extraction as a green method to recover olive pomace bioactive compounds

Abstract

Olive pomace, a by-product of the olive oil industry, is a source of valuable antioxidant compounds. This study aimed to optimize a green extraction method, combining ultrasound, stirring, and β-cyclodextrin (BCD) aqueous solutions to recover the bioactive compounds from this olive by-product. The optimal conditions to maximize extraction yields of antioxidant compounds in water or ethanol were: solid-to-solvent ratio 1:20 w/w, ultrasonication time 10 min, stirring time 21 hrs, and extraction temperature 60°C. The addition of BCD to water allowed to improve the extraction of bioactive compounds. Furthermore, the analysis of freeze-dried extracts using differential scanning calorimetry, scanning electron microscopy, and colorimetry showed that BCD interacted with certain olive pomace bioactive compounds. The presence of BCD modified the dehydrated extract's physical properties (stability, hygroscopicity, and appearance). Results showed that the studied BCD ultrasound-assisted extraction method could be an attractive and ecological option to extract the value-added compounds from industrial by-products. Practical applications: Olive pomace is produced in massive quantities each year worldwide, which is an environmental concern. Therefore, the extraction of its phenolic compounds and unsaturated fatty acids can contribute significantly to this olive by-product management and generate additional income for farmers and producers. Although the present study outlines a green extraction method at a laboratory scale, it can be scaled up since the studied technologies are available for industrial applications. The β-cyclodextrin ultrasound-assisted extraction is proposed as a green method to obtain a powdered ingredient with antioxidant properties, which could be applied in the development of functional food formulations.