Solid−Liquid Transfer of Biophenols from Olive Leaves for the Enrichment of Edible Oils by a Dynamic Ultrasound-Assisted Approach

A continuous approach assisted by ultrasound for direct enrichment of edible oils (olive, sunflower, and soya) with the main phenols in olive leaves (i.e., oleuropein, verbascoside, apigenin-7-glucoside, and luteolin-7-glucoside) has been developed. Multivariate methodology was used to carry out a detailed optimization of the enrichment, and quantitation of the transferred compounds was based on LC−MS−MS in multiple reaction monitoring optimizing the most sensitive transition for each biophenol. Under the optimal working conditions, only 20 min is necessary to enrich the edible oils with 14.45−9.92 μg/mL oleuropein, 2.29−2.12 μg/mL verbascoside, 1.91−1.51 μg/mL apigenin-7-glucoside, and 1.60−1.42 μg/mL luteolin-7-glucoside. The enrichment method is carried out at room temperature and is organic-solvent-free; thus, the healthy properties of the edible oils improve as does their quality. Also, the low acquisition and maintenance costs of an ultrasound source and its application in a dynamic system make advisable the industrial implementation of the proposed method.