Butter is defined is a fat concentrate product obtained by churning, cream, gathering fat into a compact mass and working it. Butter is made exclusively from milk or cream with or without common salt and colouring matter and contains not less than 80% fat. In butter, fat is present in continuous phase and water is present in dispersed phase. This phenomenon is known as phase inversion.
The essential feature of churning involves destabilization of lipid phase emulsion by means of mechanical agitation. Churning is initiated by agitation and the incorporation of numerous small air bubbles. Partially denatured fat globules gather at the fat/plasms inter face, where they form, small clumps. A portion of this hydrophilic fat spreads over the surface of air bubbles causing them to collapse.
Prior to working of butter granules in the churn, approximately 80% of the fat phase exists as globular fat. As the butter granules are worked more and more fat globules are crushed causing the release of liquid fat. This free fat constitutes the continuous phase. Fat globules and finely dispersed droplets of the aqueous. Phase represent the dispersed phase.