LABEC M-MIA-A - Manual (Page 60)

Ultrasonic milk analyser
3.4. Making the determination:
Sample preparation for analyses.
The milk (whey, cream, and buttermilk) is well shaken. If needed, the sample
is heated slowly up to 38-40
о С, it is well mixed and cooled down to 20 о С.
Mixing and pouring are done at least three times in dry and clean vessel.
3.5. Making the measurement
The weight plate with 20-30 g washed out and tempered sand and glass rod
is dried at 102±2
о С for 1 h, and then is taken out, covered with the cap,
tempered with exicator (up to 30 min) and the mass is weighted with
accuracy up to 0,0005 g. In the weight plate, using pipette, at about 10 сm
3
milk are poured, covered and weighted. With the help of the glass rod milk is
well mixed with the sand and without a cap is heated on a water-bath till a
homogenous mass is formed. Then the weight plate is put in a drying-oven at
temperature 102±2
о С, it is dried out for 3 h, it is taken out of the oven,
covered with the cap, tempered in exicator (up to 30 min) and the mass is
weighted. Weight-glass is placed in the drying-oven again and is dried 1 h,
then is taken out, tempered and weighted. This procedure is repeated till the
difference between two consequent measurements becomes not more than
0,004g. In case that at the second or following drying procedure mass
increases, then for the calculation is taken the previous measurement.
3.6. Calculating the results
Water content in grams for 100 g product (milk or milk derivatives), is
calculated by the formula:
Where
М1 - the mass of the plate with the sand and the glass rod, g;
М2 - the mass of the plate with the sand, the glass rod, and the sample
before drying, g;
М3 - the mass of the plate with the sand, the glass rod, and the sample after
drying, g;
The dry substance (Y) is calculated using the formula:
Y= 100 - Х,
Where:
Х is the calculated water content.
3.7. Measurement accuracy.
100
1 2
3 2
∗
−
−
=
M M
M M
X