Edible oils as a co-extractant for the supercritical carbon dioxide extraction of flavonoids from propolis

Propolis is a good source for flavonoids, however, their recovery is challenging, as it is a waxy material. This study investigated edible oils virgin coconut oil (VCO), corn oil (CO), and ghee (G) as co-extractants for the supercritical carbon dioxide (scCO(2)) extraction of flavonoids from the propolis. The extraction of flavonoids using 20% VCO as co-extractant with scCO(2) (25 g/min) for 210 min at 150 bar and 50 degrees C was found to be the most appropriate, yielding a total flavonoid content (TFC) of 11.7 mg/g and 25% TFC recovery. At a higher temperature (60 degrees C) and pressure (250 bar and 350 bar), the propolis became softer and compressed causing the extractions to retrograde. The extraction curves correlated to the diffusion model with 1.6% (AARD). The matrix diffusivities increased from 4.7 x 10(-11) m(2)/s (scCO(2)) to 6.9 x 10(-11)-21.4 x 10(-11) m(2)/s upon the addition of edible oils. Thus, edible oils could be used with scCO(2) to improve the flavonoid extraction from propolis.