From Waste to Preservation: Assessing the Protective Effect of Fruit By-Products Extracts on the Oxidative Stability of Edible Vegetable Oils

The valorization of agro-industrial fruit by-products as sources of natural antioxidants represents a sustainable strategy to replace synthetic additives in food preservation. This study systematically evaluated the phenolic composition and antioxidant activity of extracts from thirteen underutilized Colombian fruit by-products (peels, seeds, and calyxes) and assessed their protective effect against lipid oxidation in an edible vegetable oil (EVO) model system over 15 days at 60 °C. Total phenolic content (TPC) ranged from 23.1 to 2553.2 mg GAE/100 g. Orange peel (OP) and pineapple peel (PP) exhibited the highest TPC and strongest antioxidant activity, effectively inhibiting the formation of lipid hydroperoxides, hexanal, nonanal, and TBARS, and outperforming synthetic antioxidants (BHA, BHT, TBHQ) in several parameters. Multivariate analyses classified the extracts into high-efficacy, moderate-to-low efficacy, and pro-oxidant groups. HPLC-ESI-MS/MS characterization of OP and PP revealed diverse phenolic acids (gallic, caffeic, ferulic, p-coumaric, vanillic, sinapic) and flavonoids (quercetin, rutin, catechin, C-glycosylated derivatives), which are related to the antioxidant properties observed. Pearson correlation analysis revealed a positive correlation between TPC and oxidation inhibition (r = 0.89–0.94). These findings demonstrate that Colombian fruit by-products, particularly OP and PP, are promising sustainable sources of natural antioxidants for enhancing the oxidative stability of edible vegetable oils within a circular bioeconomy framework.