Olive pomace as source of bioactive substances in the preparation of functional ingredients

In this study, olive pomace from two cultivars (Carolea and Leccino) underwent extraction processes by solvents at different polarity and selectivity (aqueous mixture of ethanol, acetone, acetone, and tetrahydrofuran), providing extracts with high-value characteristics. Olive oil production residues are caching attention as potential sources of energy and bioactive compounds able to reduce oxidative specie. Meanwhile, these products pose environmental challenges due to their large-scale generation in a short period. The chemical composition of the extracts has been investigated by in vitro assays, returning wide ranges of total phenolic (26.1-59.4 mg GA/g) and flavonoid (19.9-65.4 mg CT/g) contents, while antioxidant performances were evaluated both in organic (IC50 = 0.072-0.320 mg/mL) and aqueous (IC50 = 0.025-0.090 mg/mL) environments. The UHPLC-DAD analyses allowed the quantification of tyrosol, luteolin and naringenin as the compounds mainly responsible of the health benefits. The most performed extract (Carolea cultivar and water/ethanol 30/70 v/v) was selected to be involved in an ecofriendly molecular grafting process on corn starch polymeric chain, providing a functional ingredient for food industry application. The conjugate displayed an increased content of both phenolic (49.9 mg GA/g) and flavonoid (14.6 mg CT/g) compounds, as well as antioxidant performances against DPPH (IC50 = 0.210 mg/mL) and ABTS (IC50 = 0.181 mg/mL) compared to the commercial corn starch that did not return any biological benefits. This research highlights the potential valorisation of olive pomace as source of bioactive compounds, demonstrating the feasibility of using the hydro-alcoholic extracts in food applications through innovative and sustainable processing techniques.