Van Arsdel
(1973) reported that the bulk density of food product dried to the
same water content is dependent on the rate of shrinkage; this in
turn is strongly affected by the drying method and the drying
conditions such as temperature and air flow within each method.
Similarly, longer drying times at 85 C in all drying methods might
have resulted in internal cell destruction and excessive shrinkage of
blueberries and hence high bulk density. As noted here, longer
drying times leads to more shrinkage and higher bulk density
values which was quite evident in blueberries processed in the
forced air dryer.