The lyophobic colloid present in the milk is casein.
A colloid is primarily a heterogeneous mixture in which the minute particles of one substance are dispersed in another substance, called the dispersion medium.
Classification of colloids
Based on the nature of the interaction between the dispersion medium and the dispersed phase, colloids can be classified into lyophilic and lyophobic.
Lyophilic – If the dispersed phase has an affinity for the dispersion medium, the colloid is called a lyophilic colloid.
Examples – Starch, rubber, protein, etc.
Lyophobic – If the dispersed phase has little or no affinity for the dispersion medium, the colloid is called a lyophobic colloid.
Examples – Solutions of metals like silver and gold, sols of metallic hydroxides, etc.
Major proteins in Milk
- Casein and whey protein are the major proteins of milk.
- Casein constitutes approximately 80%(29.5 g/L) of the total protein in bovine milk, and whey protein accounts for about 20% (6.3 g/L).
- The nitrogen content of milk is distributed among caseins (75%), whey proteins (18%), miscellaneous proteins (2%) and non-protein nitrogen (5%).