Optimization Hydrothermal Extraction of Phenolic Compounds from Olive Oil Industry Waste ( Olea europaea L.)

ABSTRACT

This research aimed to evaluate the waste derived from the industry of olive oil as a source of natural antioxidants, through the design and optimization of a green method for obtaining an extract rich in phenolic compounds. A hydrothermal method was optimized to recover antioxidant‐rich phenolic compounds from olive pomace. Using a Box–Behnken design, the study identified optimal extraction conditions as 0.54% acetic acid, 120°C, and 15 min. Under these conditions, the extract yielded 13.86 mg caffeic acid/g ⁻¹ of o‐diphenols (ODP), 22.45 mg caffeic acid/g ⁻¹ of total phenolic compounds (PC), an antiradical activity of 81.47% inhibition (DPPH), and a reducing activity of 3.09 mmol trolox/g ⁻¹ (FRAP). The profile was characterized by high levels of oleuropein aglycone, hydroxytyrosol hexose, and quinic acid, with hydroxytyrosol hexose identified as the primary contributor to the extract's antioxidant power. Validation experiments confirmed the model's strong predictive capacity, particularly for ODP and DPPH. Compared to traditional ethanolic maceration, this green hydrothermal process proved more efficient, offering a simple, scalable, and environmentally friendly alternative for valorizing olive industrial waste within a circular economy framework.