LABEC M-MIA-LA User Manual
Page 85
Ultrasonic milkanalyser
Operation manual
04.11.09
83/107
confidence that will show 99% of all freezing point determinations on milk
without added water:
“if the freezing point is –0,525
°C or below, milk may be presumed to be free
of water or may be confirmed as water free by tests, specified below. If the
freezing point is above –0,525
°C, milk will be designated as “presumptive
added water” and will be confirmed as added water or added water free by
tests specified below. Evaluate extreme daily fluctuations in the freezing point
of herd, pooled herd, or processed milk for presence of added water”.
“Presumed added water”, as described above, must be “confirmed” by means
of tests on authentic milk samples obtained as specified in the АОАС
METHODS.
After determination the freezing point of your sample via the milk analyser,
the added water is calculated using the following formula:
Where:
FrPointBase is the basic freezing point
FrPointCalc is measured freezing point
Note:
If the freezing point is not correctly determined, the result for the added water
is not valid. In this case results for FrPoint and AddWater are not shown on
the display and on the printout from the printer. If the density of the measured
sample is 0, the result for AddWater is not valid and is also not shown on the
display and the printouts.
Sample:
First variant
If you’ve entered for milk analyser basic freezing point -0.520
°C (according
article 5.9 of the EU Milk Hygiene Directive 92/46/ЕЕС), measured freezing
point –0.540
°C, using the above pointed formula you’ll receive –3,8%.
Because it is not possible the added water to be negative value, the milk
analyser indicates 0% added water. The reason for this is the tolerance in the
basic freezing point, reasons for which are described below.
If in the same milk we add 3,8% water, and the basic freezing point is the
same, the milk analyser will measure freezing point –0.520
°C, and will
indicate again 0% added water.
Second variant
[%]
100
int
int
int
∗
−
=
Base
Calc
Base
FrPo
FrPo
FrPo
AddedWater