Oftentimes foods gain or lose
water to such an extent as to affect their weight; for example, one
hundred pounds of flour containing 12 per cent of water may be reduced
in weight three pounds or more when stored in a dry place, or there may
be an increase in weight from being stored in a damp place. In tables
of analyses the results, unless otherwise stated, are usually given on
the basis of the original material, or the dry substance.
Potatoes, for
example, contain 2.5 per cent of crude protein on the basis of 75 per
cent of water; or on a dry matter basis, that is, when the water is
entirely eliminated, there is 10 per cent of protein.
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