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Principle of Butter Making

There are essentially four types of butter-making processes:

i. Traditional batch - churning from 25-35% milk fat cream;

ii. Continuous floatation - churning from 30-50% milk-fat cream;

iii. Concentration process - whereby plastic cream of 82% milk-fat is separated from 35% milk fat cream at 55°C and this oil-in-water emulsion is inverted to water-in-oil emulsion butter with no further draining of buttermilk

iv. Anhydrous milk fat process - whereby water, SNF and salt are emulsified into butter oil.

The process of butter making is principally an inversion of fat-in water type emulsion of cream to water-in fat type of emulsion in butter. In other words the system in which fat droplets are dispersed in continuous water phase is converted into a system of a continuous phase of fat in which water droplets are dispersed. During whipping process, cream is kept cold and the agitation stopped to produce stable and airy foam. In churning process cream is warmed to the point that softens the fat globules to some degree so that the fat inside the globules gets liquefied. Ideally the cream should attain a temperature of 12 to 18°C during churning. The persistent agitation during the process makes the softened globules to collide with each other.During the collision the material around the fat globules serving as the protective membrane and preventing the globules from coalescence is damaged. Consequently the fat globules collapse and the liquid fat cements the exposed fat droplets together.

The foam structure is broken both by the free fat and the released membrane materials, which include emulsifiers like lecithin. These materials disrupt thin water layers and thus cause bursting of the bubble walls. As soon as, enough of bubbles have been freed in the process of whipping or churning of cream, a stable foam is never formed again. Since the churning process continues further the foam gradually subsides and the butter granules are formed, which are worked together into larger and larger mass to produce butter. Fat globules typically aggregate in following three ways:
  •  Floculation
  •  Coalescence
  •  Partial coalescence

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