Recovery of acetoin from Bacillus subtilis fermentation broth by supercritical CO2 extraction

Component enrichment from fermentation broths by solvent extraction using supercritical carbon dioxide (sCO 2 ) has been demonstrated in the literature. This work investigates for the first time the feasibility of the enrichment of an acetoin fraction from a real fermentation broth at a pilot plant scale using sCO 2 . A 4-m-tall, 28-mm-diameter, counter-current column packed with pall rings was used. The ranges of process pressure and temperature investigated were 100 to 300 bar, and 37 to 80 °C respectively. The optimum recovery of acetoin was 77.8%, with little difference between the simulated and actual broths. A modest two-fold concentration of acetoin was obtained in the extract. The results show that where a modest enrichment of the targeted product makes a significant difference in subsequent separation processes, and where the purity of the product, particularly from harmful solvents, is important, sCO 2 fluid separation is a credible option for the enrichment of such products of fermentation.