Effects of pre-treatments on the yield and carotenoid content of Gac oil using supercritical carbon dioxide extraction

• Suitable air-drying temperature of Gac aril before SC-CO2 extraction is important.
• Particle size has very significant effects on the oil yield and carotenoid content.
• Enzyme pre-treatment before air-drying has a positive effect on the Gac oil yield.

The effects of air-drying temperature, particle size and enzymatic pre-treatment on the oil yield and content of carotenoids in the resultant Gac oil using supercritical CO2 extraction method were investigated. It was found that the highest oil yield was obtained when using the enzyme concentration at 0.1% (w/w) for pretreatment before air-drying. Furthermore, the content of carotenoids was also enhanced by suitable drying temperature and the particle size. High oil yield (34% g/g) and high content of β-carotene (83 mg/100 mL oil) and lycopene (508 mg/100 mL oil) were obtained using the drying temperature of 50 °C and particle size of 0.45 mm as pre-treatments prior to SC-CO2 extraction at pressure of 200 bar and extraction temperature of 50 °C. Results also indicated that the most suitable extraction time was 120 min. It was concluded that Gac oil containing high amount of carotenoids could be extracted using the chosen air-drying temperature, particle size, enzymatic pre-treatment and extraction time.