Mild sonication accelerates ethanol production by yeast fermentation

Ethanol is a renewable and environmentally benign substitute for the current fossil-fuel-based transportation fuels. Fermentation of sugars, which is, in general, a slow process, is an essential step in the production of ethanol from renewable sources. This paper reports a successful attempt to accelerate the well-known sugar fermentation process by applying soft sonication. Fermentation of glucose was carried out using Saccharomyces cerevisiae under continuous mild ultrasonication conditions. The kinetics of the fermentation reaction was monitored by ¹³C nuclear magnetic resonance spectroscopic analysis and weight loss measurements of the fermentation broth. The reaction rate constant was enhanced by 2.3 ± 0.2 and 2.5 ± 0.2 times as a result of sonication at 30 and 20 °C, respectively, as compared to a stirred reaction, and was about 10 times faster than non-stirred fermentation. The acceleration in the fermentation of glucose was observed for both 20 and 40 wt % concentrations of the glucose solution.