Antioxidant activity and total phenolic content of different extracts of delipidified olive oil pomace

Introduction: The use of by-products as a source of bioactive compounds with economic added value is one of the objectives of the circular economy. Olive oil industry is a source of olive pomace, as a by-product. The olive pomace used in the present study was the exhausted (delipidified) olive pomace, which is the by-product generated after drying and subsequent hexane extraction of residual oil from the olive pomace. This exhausted olive oil pomace may contain remaining bioactive compounds, such as phenolic compounds, which can be of interest not only for the food industry, but also for the pharmaceutical and cosmetic industries. Objectives: Various types of green methodologies, such as solvent extraction (water and hydroalcoholic), ultrasound-assisted extraction, ultra-turrax-assisted extraction and enzyme-assisted extraction (cellulase; viscoenzyme) were used to obtain extracts rich in bioactive compounds from the exhausted olive oil pomace. The bioactivity of these extracts was evaluated through the antioxidant activity. Conclusions: Among all methodologies used the extractions with enzymes produced the best yields of extraction and the conventional extraction with water at 50 °C produced the best results for the total phenolic content and antioxidant activity: ABTS, DPPH and ORAC.