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Comparative results
The moisture content of a food material is defined through the following equation:
%Moisture = (mw/msample)�
Where mw is the mass of the water and msample is the mass of the sample. The mass of water is related to the number of water molecules (nW) by the following expression: mw = nwMw/NA, where Mw is the molecular weight of water (.0 g per mole) and NA is Avadagro's number (6. � molecules per mole). In principle, the moisture content of a food can therefore be determined accurately by measuring the number or mass of water molecules present in a known mass of sample. It is not possible to directly measure the number of water molecules present in a sample because of the huge number of molecules involved. A number of analytical techniques commonly used to determine the moisture content of foods are based on determinations of the mass of water present in a known mass of sample. Nevertheless, as we will see later, there are a number of practical problems associated with these techniques that make highly accurate determinations of moisture content difficult or that limit their use for certain applications. For these reasons, a number of other analytical methods have been developed to measure the moisture content of foods that do not rely on direct measurement of the mass of water in a food. Instead, these techniques are based on the fact that the water in a food can be distinguished from the other components in some measurable way.
