Bulk Method. Bulk drying is generally carried out in
a tray dryer like batch drying. However, the product is
poured into a bulk pan and dried as a single unit.
Although the product is spread throughout the entire
surface area of the shelf and may be the same thickness
as product dried in vials, the lack of empty spaces within
the product mass changes the rate of heat input. The
heat input is limited primarily to that provided by
contact with the shelf as shown in Figure 5