where Deff – diffusion coefficient [m2
/s], s – drying time [min],
L – half-thickness of the sample [m].
The content of dry matter of untreated, ultrasound treated and
dried samples was measured according to the Polish Standard
PN-90/A-75101/03 by drying at 105 C to the constant weight [33].
Water activity in raw, pre-treated and dried carrot was examined
using hygrometer Aqua Lab CX-2 (Dekagon Device Inc., USA)
with the accuracy of ±0.001.