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The Electric Conductivity as a Parameter for Milk Quality Appreciation
© The Author(s); licensee BioMed Central Ltd. 2003
- Published: 31 March 2003
- Electric Conductivity
- Osmotic Pressure
- Milk Sample
The main components of the milk are: proteins (casein, lactalbumin, lactoglobulin), lactose, fat and mineral salts. The lactose concentration depends on several factors among which the health condition of the cows and the acidifying of the milk. In our days the chlorine/lactose ratio is used as a parameter for appreciating the milk quality. Although milk is isotonic with blood, the two biological liquids are very different in mineral composition, in concentration, and also in the proportion of ionised and bound to proteins forms. The osmotic pressure of the milk remains constant, and therefore when the lactose content is lower, the electrolytes are rising. Mainly, the equilibration is due to the chloride, probably the NaCl. This explains the variation of the electric conductivity.
We conclude that the electric conductivity may be used for the appreciation of milk quality. High values show in fresh milk a high chlorine/lactose ratio, which occurs in case of mastitis. This method may be used instead of the chlorine/lactose ratio, which is more difficult to determine.
The electric conductivity increases also with the acidifying of the milk when from 1 molecule of lactose 4 molecules of lactic acid are formed due the lactic fermentation of lactose. The proportion of ionic dispersed salts increases too, when casein changes (by acidifying) from calciumcaseinat in free casein.
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