LABORATORY CATALOGUE for milk analysis - Labochema

Required equipment
1. Calibrated butyrometer with suitable stopper in accordance with
DIN 12836-A 4, DIN 12836-A 6, DIN 12836-A 8, DIN-12836-A 5
2. Pipette DIN 10283-p for milk or pipette DIN 12837-A for milk
3. Pipette DIN 12837-B or 10 ml measuring tap for sulphuric acid
4. Pipette DIN 12837-C for 1 ml amyl alcohol
5. Centrifuge for determining fat content in milk, heatable, with rpm counter.
When used under a full load, this centrifuge must be capable of producing a
centrifugal force of (350 ± 50) g on the inside of the butyrometer stopper within
2 minutes at the most. With a rotation radius of e.g. (26 ± 0,5) cm up to the inside of
the butyrometer stopper, which is the distance between the point of torque and the
butyrometer stopper, this centrifugal acceleration is reached at a rotation speed
of (1100 ± 80) min–1.
6. Tempering devices for butyrometers, e.g. a (65 ± 2)°C water bath
With a heated centrifuge, a centrifuge bushing can be used to attach the butyrometer
into the water bath. The read-off temperature must be (65 ± 2)°C.
Preparation of the test specimen
The milk in the specimen bottle is heated up to 20°C and thoroughly mixed through
gentle shaking. This is done to bring about an even distribution of fat and to prevent
frothing and the formation of butter.
Milk fat is lighter than water and creams if it is left standing. A fat-rich layer accumulates
on the surface. Stirring and careful shaking restore the original distribution.
If the layer of cream cannot be evenly distributed in this way, the milk should be slowly
heated to 35-40°C and gently swirled around until a homogenous fat distribution is
achieved. The milk is then cooled to 20°C before being drawn into the pipette.
Foam breaks the fat globule coating. The milk may begin to turn into butter when stirred
and uniform distribution of fat is no longer possible.
The fat liquefies at 35-40° and the distribution process is speeded up.
After the temperature has been set, the milk can stand for 3 to 4 minutes to allow any
pockets of air to disperse.
The volumeters are calibrated at 20°C. Any variations in temperature will influence the
volume. Air pockets reduce the density and hence the mass of milk measured.
Laboratory catalogue for milk analysis
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