There are no published reports available on the
consequences of Tg on hot air drying, nevertheless the
knowledge gained in other types of drying can also be
logically applied in this process.
Hot air drying (xed or
¯uidised bed) is normally employed to dry solid foods.
There exists glass transition related problems during
drying of sugar-rich products such as fruit leathers and
other products which are extremely sticky. These products
appear wet even at very low moisture content. The
leathery texture of these products even at lower moisture
content is due to the plasticising eect of low molecular
weight sugars which depress the Tg. Drying of other
fruits may pose problems, particularly if there is an excessive
disruption of skins or tissues resulting in leaching
of sugars out on the surface.