Evaluation of energy efficiency and quality parameters by drying beets with a refractive window (Beta vulgaris)

This study evaluated the energy efficiency associated with drying by refractance window™ and its effect on the physical and chemical properties of beetroot in two different physical states, in semisolid (puree type) and solid (slices) were compared. The refractance window™ drier was compared to a tray dryer at 70 °C on the food surface. The drying time was calculated through the kinetics in both dryers in both physical states of the beetroot determining the moisture content at the beginning and the end of the drying process after which water activity and color retention were determined. Total polyphenol and flavonoid contents respectively, and antioxidant activity were evaluated. Overall energetic efficiency for both dryers was calculated. The beetroot dried in semisolid state using the refractance window™ technology retained color and showed no differences when compared with fresh beetroot. No significant differences in total polyphenol content and total flavonoid content when compared with the fresh sample after application of the refractance window™ were found. The overall energetic efficiency was higher after using refractance window™ drying in beetroot in the two physical states and produced greater retention of quality parameters when compared with the tray dryer.