Mathematical modelling for sustainable extraction of oil from rice bran, safflower seeds and flaxseeds employing supercritical carbon dioxide at pilot scale: An insight to comprehensive physico-chemical analysis

Abstract

This study reports the supercritical carbon dioxide extraction of oil from rice bran, safflower seeds, and flaxseeds performed at varying conditions of pressure (250–450 bar), temperature (45 and 60 ⁰C) and supercritical carbon dioxide flow rate of 1 kg/min at pilot scale. The oils obtained were evaluated for yield, fatty acid composition and other physico-chemical properties. They were compared with the oil obtained using supercritical carbon dioxide extraction and the conventional extraction method with n-hexane. The total mass yields obtained by both the methods were comparable. The highest experimental extraction yields were obtained at 450 bar 60 ⁰C for rice bran oil (16.2 %), safflower oil (27.8 %), and flaxseed oil (30.8 %), at 1 kg /min flow rate of supercritical carbon dioxide which was considered optimal at the studied conditions. It was observed that the extracted oils via supercritical carbon dioxide exhibited enormous reduction in phosphorus content of rice bran oil (3.5 ppm), safflower oil (1.2 ppm) and flaxseed oil (2.32 ppm) as compared to conventional extraction. Rice bran oil extracted by supercritical carbon dioxide retained most of the antioxidant contents, oryzanol as compared to Soxhlet extracted oil and contained significantly lower (1.3 %) amounts of wax. Further, extraction curves were evaluated by a mathematical model where broken and intact cells was applied to consider mass transfer kinetics of extracted oil.