ABSTRACT
The thin sheet containing heat-sensitive materials,
such as vitamins, can also be dried at a lower tem-
perature in a vacuum.
The irreversible thermochemical transformations
during the slurry’s first contact with the hot drum can
also be used to simultaneously impart certain re-
quired quality of the dried product.6 Starch slurries
can be gelatinized or ‘‘cooked’’ before the sheet is
dried to produce pregelatinized or ‘‘precooked’’ starch
for instant food formulations. Exposure of the thin
sheet to the high heat flux and high temperature for a
short period of time can also impart a porous struc-
ture to the dried sheet because of the rapid formation
of vapor bubbles within the sheet during ‘‘boiling-
like’’ drying. Porous products are excellent in instant
food formulations because they are more readily wet-
ted and can be easily rehydrated. It is for these
reasons that the drum dryer is widely used around
the world in the production of pregelatinized starch
for instant food formulations.
