The moisture content of milk powder is of great importance.
It is one of the predominant factors determining
the keeping quality of the product. The rate of
(bio)chemical reactions is dependent on the moisture
content, or more precisely on the ‘availability’ of water
for these reactions. Legal limits and trade agreements
dictate that milk powder shall meet certain requirements
with respect to the moisture content. In order to check
that these requirements are met, the moisture content of
milk powder has to be determined by means of an accurate
and precise method of analysis.
There are several methods for the determination of the
moisture content of milk powder, among which the drying
oven method is the most widely used. In the European
Union a drying oven method has been prescribed
for official inspection purposes. The principle of this
method, based on IDF Provisional Standard 26A : 1993,
is to remove the water by heating a test portion in
a drying oven at 102$1°C until constant mass of the test
portion is obtained.
The conditions of three drying oven methods are given
in Table 1.
In 1987 the Methods of Analysis Group of Asfalec
evaluated the repeatability and reproducibility of the
IDF Standard by means of an international collaborative