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Human milk is
universally regarded ideal for the feeding of infants. Yet,
owing to various causes, an infant may not derive adequate
nutrition from the mother and it may become necessary to
feed the infant either wholly or partly with milk from other
sources such as infant milk food. Water activity is an
important concept in the food industry since it is related
to microbiological stability and physico-chemical
deteriorative reactions. The present investigation was
carried out with specific objective to determine water
activity (aw) of infant milk food at different temperatures
and also to evaluate and compare BET and GAB models with
data observed during investigation. Gravimetric method was
used to determine the equilibrium moisture content (EMC) of
infant milk food at different temperatures (30, 40 and 50°C)
by keeping the samples in a range of atmospheres of relative
humidity from 11.1 to 92.3%. The EMC's of intermediate milk
food was found to vary from 0.0185 to 0.4432 (db). The data
recorded could be fitted to GAB model satisfactorily for the
entire range of water activity with acceptable values of
coefficient of determination in the range of 0.962 to 0.984.
The BET model provided a good description of the isotherms
of infant milk food only in the range of water activity <
0.45.
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