Influence of ultrasonic pretreatments on drying kinetics and quality attributes of sweet potato slices in infrared freeze drying (IRFD)

The influence of ultrasound (US) application before infrared freeze drying (IRFD) on drying kinetics and quality characteristics of sweet potato samples was evaluated. Results indicated that the proper ultrasonic power could cause the formation of micro-channels and the production of a more porous matrix facilitating moisture diffusion and reduce the drying time in IRFD process. The US pretreatment could increase 4-42% of the beta-carotene content in comparison with the untreated ones. Consequently, the US pretreatments can improve the quality of dried sweet potatoes while shortening the drying time.