LABEC M-MIA-A - Manual (Page 67)

Ultrasonic milk analyser
2.1.4. Determination of casein content in the milk
А/ Kjeldahl method
The total nitrogen content in the milk is determined. Casein is precipitated
with acetic acid (acetate buffer) and is filtrated. The content of nitrogen in the
filtrate is determined. Casein content is the difference between the two results
for nitrogen using the Kjeldahl’s method.
B/ Titration with formalin
More details for this method – see Appendix Methods.
2.1.5. Determination of salts in milk.
For the salts in milk and its derivatives is judged by its ashes content. Milk
dries, becomes carbonized and turns to ashes till constant mass. The ashes
received are calculated in percentage.
2.1.6. Determination of solids in milk
Solids describe the content of fats, proteins, carbohydrates and salts. Its
value may be used for determination of each of these parameters in case of
known other values.
Solids are determined by drying till constant mass – see Appendix Methods.
Express methods by using another milk analysers
It is possible another device to be used for determination of some of the
quality parameters of milk and its derivatives samples, intended for
calibration, but it has to be noted that it is possible incorrect values to be
received, that’s why it is necessary to be completely sure in the accuracy of
their readings.
Usage of
our and other milk analysers based on the infrared
measurement principle.
By using it the fat, lactose and protein content may be determined. Problem
may arise with determination of salts and SNF. This is due to the impossibility
of the infrared method to determine the solids and in order to receive the
solids in the sample their meaning is accepted as a constant.
Operation manual MRC.VER.01-02.10