Fluidized bed drying of blackberry wastes: Drying kinetics, particle characterization and nutritional value of the obtained granular solids

Particulate systems for functional ingredient development were obtained by fluidized bed drying of blackberry wastes. Fluidization behavior, drying characteristics, and physicochemical and functional propertieswere studied at different air temperatures (50, 60 and 70 degrees C) and an airflow rate of 6 m/s. Under these conditions, the blackberry waste -a heterogeneous and high-humidity material- could be successfully transformed into granulates under bubbling fluidization regime and without the use of inert material. The Page model was the most suitable to predict the blackberry waste drying behavior. Drying rate increasedwith temperature and the time to reach a granulate of aw < 0.3 was reduced from 30 min (at 50 degrees C) to 12 min (at 70 degrees C), producing particles of lower humidity and size with fair flowability. The optimal operating condition was a 60 degrees C temperaturewhich allowed to produce a mean-size particle granulate, with fair flowability (Carr index= 15.9 +/- 1.4%), and high in dietary fiber content (79.9%+/- 0.4%), polyphenol content (1800 +/- 34mg GAE/100 g) and antioxidant capacity (approximate to 1088 +/- 57 GAE/100 g by ABTS and 1012 +/- 93 by FRAP methods). Additionally, a better balance between the fiber types and high retention of blackberry pigments and color was obtained. (c) 2021 Elsevier B.V. All rights reserved.