α-Relaxation in honey study versus moisture content: High frequency ultrasonic investigation around room temperature

Ultrasonic longitudinal attenuation and velocity have been measured for various frequencies between 0.5 and 13.5 MHz versus temperature, in honeys with moisture contents between 15% and 19%. With the help of attenuation measurements, the temperature of the alpha transition T_α (associated with the glass transition) has been deduced versus moisture content and ultrasonic frequency. Regarding the high sensitivity of T_α towards moisture content, one can distinguish two honeys with moisture contents difference less than 0.1%. Considering the fact that the experiments are not difficult to perform and are carried out at around room temperature, this technique could be useful for honey quality control or more generally for aqueous polymers study.