Ultrasonic monitoring of malolactic fermentation in red wines

• The ultrasonic velocity successfully monitors the malolactic fermentation process.
• Significant correlations were observed between ultrasonic velocity and malic acid, lactic acid and UFC parameters.
• The ultrasonic velocity could be used to predict the end of the malolactic fermentation process.

The progress of malolactic fermentation in red wines has been monitored by using ultrasonic techniques. The evolution of ultrasonic velocity of a tone burst 1 MHz longitudinal wave was measured, analyzed and compared to those parameters of oenological interest obtained simultaneously by analytical methods. Semi-industrial tanks were used during measurements pretending to be in real industrial conditions. Results showed that the ultrasonic velocity mainly changes as a result of the conversion by lactic acid bacteria of malic acid into lactic acid and CO2. Overall, the present study has demonstrated the potential of the ultrasonic technique in monitoring the malolactic fermentation process.