LABEC M-MIA-A - Manual (Page 93)

Ultrasonic milk analyser
APPENDIX 8 CONDUCTIVITY MEASURING
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. 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 Should indicate the development of mastitis.