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GEA Niro Method No. A 1 b |
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Revised: September 2006 |
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1.
Definition
The moisture content of a powder
is the loss in weight (%) after oven drying at 102°C for 3
hours.
2.
Scope
This is a routine method which may
be used for milk powder and all other powdered dairy products which do not
contain crystallized lactose
(α-lactose-monohydrate).
3.
Principle
Sample is dried by oven drying at
102°C ± 2°C for 3 hours.
4.
Apparatus
4.1 Drying oven, with
thermostat and without forced air circulation.
4.2 Analytical
balance, sensibility ±0.1 mg.
4.3 Desiccator with
colour-indicating desiccant (e.g. silica gel).
4.4 Weighing dishes
with lid.
5.
Reagents
None.
6.
Procedure
6.1 Dry weighing dish
with open lid in the oven, and cool it in desiccator.
6.2 Weigh the empty
dish (a), add approx. 3 g of powder and weigh
again
(b).
6.3 Place the loaded
dish with open lid in the oven at 102°C ± 2°C
for
3 hours.
6.4 Cool closed dish
to room temperature in desiccator, and weigh (c).
7.
Calculation
a = weight of empty
dish
b = weight of dish +
powder
c = weight of dish + dried
powder
8.
Reproducibility
± 0.1 %
9.
Remarks
A sample for moisture
determination has to be handled carefully in order to avoid evaporation or
prevent adsorption.
Moisture content of a powder
sample depends on the drying time, our experience has shown that 3 hours is
sufficient.
10.
Literature
• N iro Research Laboratory
• IDF Standard № 26:2004 /
ISO Standard № 5537:2004
• De Knegt, R.J.
and Brink, H.v.d.: Improvement of the drying oven method for the Determination
of the Moisture Content of Milk Powder. Int. Dairy Journal, 8, 1998, pp.
733-738.