Influencia de la aplicación de ultrasonidos de potencia en las cinéticas de secado, el contenido polifenólico y la capacidad antioxidante de manzana (cv. Granny Smith)

The main objective of this study was to evaluate the effect of power ultrasound application on hot air drying kinetics of apple and polyphenol content and the antioxidant capacity of the dried product. For this purpose, apple (Malus domestica cv. Granny Smith) cubes (10 mm side) were dried in a convective drier, at constant air velocity (1 m/s), different temperatures (30, 50 and 70ºC), without (0 W) and with the application of power ultrasound (45 W and 75 W). Both high temperatures and power ultrasound application led to a significant (p<0.05) reduction of drying time and increased the effective moisture diffusivity. In overall terms, the antioxidant capacity and polyphenol content of apple samples was better preserved when the drying time was shortened. Therefore, ultrasonic application could be considered an adequate technology with which to intensify convective drying of apple preserving antioxidant capacity.