A simple method for preparing chlorophyll free phenols from olive leaves and efficiently enriching it in refined olive oil

Abstract The refining process almost completely removes phenols from refined olive oil (ROO). Enriching ROO with olive phenols can significantly enhance its quality and health benefits. However, current enrichment methods are inefficient and overlook the negative impact of chlorophyll present in the phenol extract on the oil. In this study, we developed a straightforward two-step dissolve and resaturate process to prepare chlorophyll-free phenols from olive leaves and efficiently enrich ROO using the ultrasonic pulsed probe method. Under optimal conditions, the total phenol content in ROO increased by 424 mg/kg, including increases of 158.5 mg/kg (37.4%) for oleacein, 29.5 mg/kg (7.0%) for hydroxytyrosol, and 17.9 mg/kg (4.2%) for oleuropein aglycone. This also significantly enhanced the antioxidant activity, oxidative stability, and some flavor characteristics of ROO. Our study offers a straightforward, practical, and effective strategy for the valuable use of olive leaves and for improving the quality of ROO.