Thermal Analysis of Conventional and Extractive Fed-Batch Ethanol Fermentation at Different Temperatures

Very high gravity (VHG) ethanol fermentation at low temperatures can be a way to obtain wines with high ethanol content (> 15 °GL). The production of vinasse is lower, compared to typical industrial conditions, which reduces the costs of storage and transport. However, there is greater heat generation during cell growth, resulting in an increased requirement for cooling water. One promising way to cool the vat is to use CO 2 stripping, which removes heat by vaporization of the ethanol and water in the broth. Therefore, the aim of the present study was to find suitable operating conditions, considering the gas flow rate ( F_CO_2 ) and the stripping start ( t_start ) and stop ( t_stop ) times, that could reduce the volume of water required for temperature control. Simulations of extractive fermentations at 28 and 34 °C, with must substrate concentration ( C_SM ) of 300 g/L, were performed to obtain F_CO_2 , t_start , and t_stop . Experimental validations showed water volume reductions of 66.4