Study and comparison of two combined processes for dehydration of raspberries

ANABEL RODRIGUEZ ; MARÍA M. RODRIGUEZ; MARÍA L. LEMOINE ; RODOLFO H. MASCHERONI

DRYING TECHNOLOGY

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2017 vol. 35 p. 689 - 698

0737-3937

Two alternatives of combined drying were examined and compared for dehydration of raspberries (cv. Heritage). A portion of raspberries was pretreated with osmotic dehydration (60ºBrix sucrose solution-20ºC-360min) and another with hot air drying (60ºC-1.5m/s-300min). Pretreated raspberries were then dried by microwave at different microwave output power values (160W, 350W and 500W). The combined processes were also compared with microwave drying alone (control). Physicochemical properties (water content, water activity and drying rate) and quality parameters (optical properties, mechanical properties, antioxidant capacity and rehydration capacity) of dried raspberries were evaluated. Results showed that the microwave output power level at 350W allowed a high yield of dried raspberries. The combined processes were not efficient (low drying rate) to reduce the water content. The method hot air-microwave drying achieved a good texture with a better appearance and an appropriate rehydration performance of the final product, although with a low retention of the antioxidant capacity. In consequence, the results obtained in this work are essential to improve the processing of dehydrated raspberries.