Extraction of edible avocado oil using supercritical CO2 and a CO2/ethanol mixture as solvents

- The avocado oil extraction was technically feasible in one and in two steps on higher pressures.
- It was recovered until 98% of the oil when was used two steps extraction.
- The crossover pressure from the oil solubility data was around 350-375 bar.
- The extracts of second step were more concentrated in tocopherols.

Avocado oil is similar to olive oil, it can be used as an ingredient in functional foods since it contain high contents of vitamins and phytosterols and its triacylglycerols contain high contents of unsaturated fatty acid. The present study sought to evaluate the technical viability of extraction of avocado oil by supercritical technology using GRAS solvents (Generally Recognized as Safe). Freeze-dried avocado (Persea Americana) pulp with 65% lipids was subjected to supercritical extraction in a fixed bed at temperatures of 40, 60, and 80 °C and pressures of 200, 300 and 400 bar, using supercritical carbon dioxide (scCO2) as a solvent in a first step, and a scCO2/ethanol mixture (93/7 w/w) in a second step. Extraction curves (mass of oil extracted versus extraction time) were obtained from the overall extraction yields, and from this curve the solubility of oil in scCO2 was calculated. The extraction appeared to be technically viable to obtain up to 98% oil recovery. The solubility values correlated well with the Chrastil equation, and presented similar order of magnitude to the solubility of oils reported in literature.