Churning process

Butter is essentially milk fat made from milk, dahi (curd) or cream by agitating or shaking it until the fat separates as semisolid mass from the liquid portion (serum) of milk.

The separated milk fat is known as butter, while the watery portion as buttermilk. The process of agitation/ shaking is known as churning and the device used for the purpose is butter churn.

From the aging tank, the cream is pumped to the churn or continuous butter maker via a plate heat exchanger, which brings it to the requisite temperature. A butter churn is a device used to make butter by shaking up the whole milk (or cream). Butter grains are formed by breaking down the membranes that surround the fat.

Optimum churning temperature: 9-11°C. In the churning process, the cream is violently agitated for 5-10 min to break down the fat globules, causing the fat to coagulate into butter grains, while the fat content of the remaining liquid (buttermilk) decreases.

Churning causes these grains to fuse with each other and form the butter. The liquid that is left out without fat is called buttermilk.
Churning process

Processing of buttermilk

Natural buttermilk is a byproduct of butter manufacture and is categorized as sweet (non-fermented) or acidic (fermented).

Sweet buttermilk is obtained during butter manufacture from pasteurized non-fermented cream. Depending on the processing conditions, which may involve heating the cream before ripening at 90°C for 15 seconds or 105°C- 110°C with no holding, sour cream or sweet cream buttermilk may be produces.

Sweet cream buttermilk can be further fermented by mesophilic lactic acid bacteria.

The basic manufacturing steps of cultured buttermilk involved standardization of the fat and solids-not-fat contents, followed by homogenization heating (85° C for 30 min), fermentation by starter cultures, breaking the fermentate, cooling and packaging. The buttermilk also can be powdered.

Fermented buttermilk contains around 0.7% lactic acid and traces of diacetyl in addition to protein, minerals and about 80% of the non-fermented lactose.

Only a minor percentage of the buttermilk produced is consumed directly, the commercial use of buttermilk includes applications in the baking and dairy industries.
Processing of buttermilk