Concentration control in alcoholic fermentation processes from ultrasonic velocity measurements

摘要

A study of the alcoholic fermentation of several carbohydrate aqueous solutions, using an ultrasonic velocity measurement technique, is presented in this paper. It is shown that the changes occurring during the course of an alcoholic fermentation can be monitored on-line by measuring the velocity of an elastic wave propagating through the fermenting medium. During the alcoholic fermentation, carbohydrates are transformed into ethanol and carbon dioxide by the action of the yeast's metabolism. In this work, measurements of the ultrasonic velocities and densities of the binary mixtures glucose-water, fructose-water, saccharose-water and ethanol-water were carried out. These experimental results ― due to the inaccuracy of the theoretical approaches ― have been satisfactorily utilised to determine the concentrations of the main components during the glucose and fructose fermentation, induced by Saccharomyces cerevisiae yeasts, and to analyse the saccharose fermentation.