Casein is a calcium phosphate-binding protein that constitutes up to 80% of the total milk proteins. In bovine milk, it exists in four types such as α_S1, α_S2, β, and κ. Casein can adapt its structure according to the changes in the environment and assemble in colloidal structures to form casein micelles. Casein micelles constitute about 10% of the volume in skim milk.

Appearance:Almost white, fine or fine granular powder, almost odorless slightly yellowish or grey-yellowish.
N (Nitrogen):14 - 15 %
P (phosphorus):0.7 - 0.8 %
Fats:≤ 0.2 %
Free acid (as lactic acid):≤ 0.1 %
Sulfated ash (800 °C):≤ 1.5 %
Loss on Drying (105°C):≤ 6 %
Suitability as enzyme substrate:conforms internal standard