LABEC M-MIA-LA - Manual (Page 98)

Ultrasonic milkanalyser
Operation manual 04.11.09 96/107
APPENDIX 8 CONDUCTIVITY MEASURING (ONLY FOR
DEVICES WITH EMBEDDED FUNCTION)
1. Method of determination.
Conductivity (or Electrolytic Conductivity) is defined as the ability of a
substance to conduct electrical current. It is the reciprocal of the resistance.
In a healthy animal*, the mean value of electric conductivity is:
Milk type
Conductivity values
Cow milk between 4 to 6 mS/cm (18°C);
Sheep milk between 3 to 5 mS/cm (18°C);
Buffalo between 2,5 to 5 mS/cm (18°C);
*These values depend on the geographical region, the breed and on other
factors.
Milk conductivity changes on the concentration of ions in the milk:
Added water, sugar,
proteins, insoluble
solids
Decrease the ion's concentration. Milk conductivity
decreases.
Added salts Increase the ion's concentration. Milk conductivity
increases. Often the milk is falsified by adding salt:
towards milk with good characteristics: fat 4%,
SNF 8,8, conductivity 4,5 are added salt and
water. Then the results are changed to 3,2 and
8,8, conductivity 10. In other words adding water
regulates the increased value of SNF and density
till normal (within the boundaries/parameters) and
even the fat is normal. By the values of these
parameters may be determined if the sample is
falsified, but the only characteristic, proving this is
conductivity, which is out of boundaries
nevertheless added water. But be careful, as the
falsification is not the only possible reason for
conductivity increasing. The other possibility is
mastitis that’s why we recommend using another
(chemical) method for checking it.
Significantly extreme
value (6,5 - 13,00
mS/cm (18°C) Should indicate the development of mastitis.
Infections damage the tissue of the udder. This
allows sodium and chlorine ions from the blood to