Hot air-assisted radiofrequency drying of avocado: Drying behavior and the associated effect on the characteristics of avocado powder

Hot air-assisted radio frequency drying (HA-RF) was performed to dry avocados and produce avocado powder. An electrode gap of 80 mm and sample thickness of 2 cm were selected as the ideal HA-RF drying parameters. The HA-RF drying kinetics were compared with hot air (HA) drying. The HA-RF drying resulted in a faster and shorter drying process with the higher drying rate than HA drying. HA-RF drying provided a 100% reduction in drying time (from 180 to 90 min) compared to the HA drying. The quality attributes of avocado powder obtained by HA-RF drying were also assessed by comparing with HA and freeze-dried samples. The color values, total phenolic content (TPC), antioxidant activity, porosity, dispersibility, solubility, caking degree, and hygroscopicity were affected by drying methods. The HA-RF drying resulted in higher TPC (170.91 mg GAE/100 g dw) and antioxidant activity (39.39%) in avocado powder than HA drying (154.74 mg GAE/100 g dw and 30.09%, respectively). On the other hand, freeze-dried samples had the highest TPC (202.05 mg GAE/100 g dw) and antioxidant activity (52.65%). The HA-RF-dried products exhibited the lowest color change (6.49), Carr index (21.43%), Hausner ratio (1.27), and wettability (2.07 s) compared to the HA and freeze dried samples. When all quality characteristics were considered, the HA-RF drying method was advanced to the other methods, especially in fast drying time, and was found to be the best method for producing avocado powder. Practical Applications This study explored the effect of drying methods (HA-RF drying and HA drying) on the drying characteristics and quality of dried avocado powder and its comparison with freeze drying. The study showed that HA-RF drying resulted in a shorter processing time than other drying methods. The HA-RF-dried powder quality was comparable to that of a freeze-dried one.