Supercritical fluid extraction of borage (Borago officinalis L.) seeds with pure CO2 and its mixture with caprylic acid methyl ester

The influence of different pressures of CO2 and the addition of caprylic acid methyl ester as an entrainer was studied for the extraction process of borage seed. The increase of CO2 pressure from 100 to 350 bar resulted in the increase in extract yield from 0.14 to 24.29% (w/w) while the changes in the extract composition were not so considerable. The highest solubility of pure caprylic acid methyl ester in dense CO2 was determined at 100 and 300 bar (approximately 1 g of ester in 1 g of CO2). The addition of this entrainer increased the yield of pure extract up to 47.8 times at 100 bar, 2.4 times at 200 and 300 bar. Due to the high solubility of caprylic acid methyl ester at the lower (100 bar) pressure it is easy to separate the entrainer, which constituted only 4.22% of the total borage seed extract.