Online monitoring of the redox potential in microaerobic and anaerobic Scheffersomyces stipitis fermentations.

Different ORP values were found in anaerobiosis and kLa 4.9 h-1, suggesting that for ethanol production by S. stipitis, values from - 270 to - 330 mV are favorable under the studied circumstances. In this ORP range, the greatest rates of xylose consumption and ethanol production were registered. ORP monitoring was demonstrated to be a suitable option for online control throughout the fermentation processes, which may provide a more efficient bioprocess operation with a very low O2 concentration.