Milkotester Ltd
Ultrasonic milk analyzers
10 Operating Instructions Master Pro
Sample preservation
The vessels where the samples will be put have to be clean, dry,
glass, metal or from other suitable material, to be tightly closed with rubber
or other stopples. The stopples not to absorb water and fat and not to
influence the analyses sample content.
In summer the sample fills up to the top the vessel, but in winter – at
least 3/4 from the vessel’s volume. Each sample for analyses has to be
labeled and described in a way not allowing to be mixed up.
The samples are stored in conditions, assuring temperature,
corresponding to the requirements for storing such kind of product
(advisable – 1 °С).
If there is a need of longer sample storing they have to be
preserved; the most commonly used preservative is potassium bichromate
(K2Cr2O7) - 1 g for 1 000 ml. The samples have to be stored in a cold and
dark place after the preservation. Have in mind that during the analyses
the results for SNF% will be increased with 0,1 %. After adding the
preservative the sample has to be well stirred.
Preparing the samples for analyses
Milk – raw and thermally treated
When examining samples taken immediately before analyses and
shortly stored, the milk is poured several times from vessel to vessel in
order to distribute the fat content uniformly. To avoid foam formation or
separation of milk fat, the samples have to be carefully poured using the
walls of the vessels, as they are tilted slightly. For a better mixing the
sample it has to be poured at least 3 times. When needed the same is
tempered to the temperature within the measuring range.
If there is fat stuck on the walls of the vessel and the stopple (when
the samples were stored for a long time), the milk has to be slowly heated
up to 35-40 °С. At the same time it has to be slowly shaken. The cream,
stuck to the walls of the vessel is removed. The sample is poured several
times and is cooled down (advisable up to 20°С).
If there is separated liquefied fat or white particles with irregular form on
the vessel’s walls reliable results could not be expected.
Do not make analyses if the acidity of the milk is more than 17oT
