Extraction of phenolic compounds from virgin olive oil by deep eutectic solvents (DESs)

• Deep eutectic solvent (DES) were assayed for the extraction of phenols from olive oil.
• The efficiency of DES-phenolics extraction was compared with methanol extraction.
• The phenolic compounds were efficiently recovered from olive oil with DES.
• The main extraction efficiency with DES was obtained for oleacein and oleocanthal.
• DES offers an efficient, safe, sustainable and cost effective alternative to methanol.

Deep eutectic solvents (DESs) are “green” solvents, applied in this study for the extraction of phenolic compounds from virgin olive oil (VOO). Different combinations of DES consisting of choline chloride (ChCl) in various mixing ratios with sugars, alcohols, organic acids, and urea, as well as a mixture of three sugars were used. The yields of the DES extractions were compared with those from conventional 80% (v/v) methanol/water. DES showed a good solubility of phenolic compounds with different polarities. The two most abundant secoiridoid derivatives in olive oil, oleacein and oleocanthal, extracted with ChCl/xylitol and ChCl/1,2-propanediol showed an increase of 20–33% and 67.9–68.3% with respect to conventional extraction, respectively. To our knowledge, this is the first time that phenolic compounds have been extracted from VOO oil using DES. Our results suggest that DES offers an efficient, safe, sustainable, and cost effective alternative to methanol for extraction of bioactive compounds from VOO.