The results showed a linear dependence of final moisture content
with the freezing rate. Larger ice crystals, related to lower
freezing rates in frozen samples, promote faster ice sublimation,
and, therefore, shorter primary drying time (Roy and Pikal, 1989).
For a constant drying time, smaller ice crystals and, therefore,
reduced mean pore diameter in dried external layer promotes
slower sublimation and, consequently, higher final moisture content.
In the production of rapidly disintegrating tablets using
freeze-drying there was found similar influence of freezing rate
on residual moisture of the resulting tablets (Corveleyn and
Remon, 1997).