Abstract: Whole egg liquid was dried by double-frequency (28 kHz + 28 kHz) ultrasonic vacuum drying. The effects of drying temperature, ultrasonic power, and vacuum degree on the drying characteristics of whole egg liquid was investigated. Also, the effect of ultrasonic power on the cavitation yield was explored by measuring the amount of iodine released. A mathematical model for the drying process was established. The results showed that the drying rate increased with increasing drying temperature, but the drying temperature should not be too high. Increasing the ultrasonic power and the vacuum degree was conducive to increasing the drying rate. The results of iodine release showed that increasing the ultrasonic power effectively improved the ultrasonic enhancement effect. The effective moisture diffusion coefficient was positively correlated with the drying temperature, ultrasonic power and vacuum degree. The calculated activation energy of dual-frequency ultrasonic vacuum drying was 9.76 kJ/mol, and the energy consumption for drying was low. The Page model could better reflect the dual-frequency ultrasonic vacuum drying process of whole egg liquid. The results from this study provide a theoretical basis for the study of dual-frequency ultrasonic vacuum drying.

Key words: whole egg liquid, dual-frequency ultrasound, vacuum drying, drying characteristics, mathematical modeling