LABORATORY CATALOGUE for milk analysis - Labochema

Fig. 4
Filling the centrifuge
Fig. 5
The butyrometers are brought to the exact reading
temperature in a water bath
6. Immediately after the mixture has been shaken and turned upside
down a few times, the butyrometers, still hot and with the stoppers
pointing downwards, are placed in buckets inside the heated
Gerber centrifuge (see Fig. 4), whereby the butyrometers must be
placed exactly opposite each other.
Beforehand, the column of fat should be set at the height of the
expected level of fat content by turning the stopper.
After setting the time on the centrifuge, the centrifuge is started.
After reaching a centrifugal force of (350 ± 50) g, which is reached
as a rule after 1 minute, the corresponding speed of (1100 ± 50) rpm
should be maintained for 4 minutes.
The centrifuge must be fitted with an interlocking lid. After the time
set for the centrifuge has been reached, the rotor brake is automatically
applied.
7. The butyrometers are now removed from the centrifuge, taking
care not to tilt them, and are placed with the stoppers facing downwards
for 5 minutes in a water bath heated to 65°C (see Fig. 5).
It is important to maintain an exact temperature so as to obtain accurate
results. Only a read-off at 65°C will ensure an exact result. If the
temperature is too low, the volume of the column is reduced and a fat
content reading that is too low will be indicated.
Fig. 6
Measured values can be reliably and accurately read
off with the aid of a safety reading lamp
Laboratory catalogue for milk analysis
17