Moisture sorption isotherms for spray-dried milk
powder showing a change in hysteresis due to a phase change
at 0.43 aw. When the isotherm is ended prior to the phase
change at 0.43 aw (■), there is little hysteresis. When the
isotherm is ended above the phase change (), there is
apparent, but not actual hysteresis due to the phase change.
Subsequent isotherms run on the sample after experiencing a
phase transition (▲) do not show an inflection point, are
repeatable, and exhibit only small levels of hysteresis.