Study and Comparison of Different Drying Processes for Dehydration of Raspberries

A. RODRIGUEZ; R. H. MASCHERONI; LAURA LEMOINE; MARÍA M. RODRIGUEZ

DRYING TECHNOLOGY

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2016

0737-3937

The aim of the present study was to evaluate and compare different drying methods(microwave, hot air + microwave and osmotic dehydration + microwave) in raspberries(cv. Heritage). A portion of raspberries was pretreated with osmotic dehydration (60ºBrix sucrose solution at 20ºC for 360min) and another with hot air drying (HAD) (1.5m/s air speed at 60ºC for 300min). Pretreated raspberries were then dried by microwave and at three different intensities (3.5W/g, 7.5W/g and 11W/g). Physicochemical properties (moisture 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 drying at 7.5W/g (50 min and final temperature of 79± 5.1°C) allowed a high yield of dried raspberries. The combined processes were not efficient to accelerate the decrease of moisture content, due to the low drying rate of the pretreatments. In terms of quality, none of the drying processes allowed a high retention of the antioxidant capacity. However, they allowed an appropriate rehydration performance. The combination of HAD with microwave drying allowed obtaining a good appearance and desirable texture on the dried product. Thus, this last option seems to be the best among the drying methods tested, but additional studies are required to improve the efficiency of the process and the effect on the antioxidant capacity during drying.