Biosurfactants Contribute to Distiller's Corn Oil Recovery during Ethanol Production

Distiller's corn oil (DCO) is an important coproduct of the ethanol industry. However, this oil is partially emulsified in the fermentation medium and adheres to solid particles during ethanol production. The addition of surfactants can facilitate the DCO removal. This study is the first to investigate the use of biosurfactants, biodegradable molecules with demulsifying properties, for DCO recovery. For this, two rhamnolipid (RML)-type biosurfactants, one mono-RML-rich mixture and the other, di-RML, both produced using DCO as a carbon source, were added into ethanol production at a concentration of 0.5 g/L. The chemical surfactant Tween 80 was also added as a positive control. Both biosurfactants increased the total oil recovery (thin vinasse and solids); moreover, di-RML also enhanced the DCO recovery from thin vinasse as well as Tween 80. Both surfactants did not impact the ethanol productivity. Additionally, di-RML reduced the viscosity of the reaction medium during liquefaction and simultaneous saccharification and fermentation. These findings suggest that di-RML is a viable and eco-friendly alternative to chemical surfactants, promoting enhanced oil recovery and improved process efficiency in the biorefinery and circular economic context.