12 DAIRYING 



The churning is continued at a uniform speed until the sound 

 of the cream in the churn indicates that it is becoming milky and 

 the butter is coming. 



CHURNING. 



396. Cream is churned for the purpose of separating the fat 

 globules from the serum of the cream. This is done by solidify- 

 ing the liquid fat globules and then sticking them together into 

 sufficiently large lumps or granules to float on the serum. The 

 object of churning is to accomplish this separation exhaustively 

 and within a reasonable time. 



Butter fat itself is not a simple or an elementary substance, 

 but is composed of several so-called "glycerides of the fatty 

 acids." These, component parts have different properties ; some 

 of them are hard, like tallow, while others are soft like lard, and 

 the proportion in which the hard and the soft parts are present 

 is somewhat variable. This lack of uniformity in hardness is due 

 principally to the breed of the cow and to the part of the period 

 of lactation in which the milk is produced. Jersey butter fat as 

 a rule contains more of the harder, tallowy parts than is com- 

 monly found in average butter on the market, while Holstein but- 

 ter fat is below the average in this particular, and contains a 

 large proportion of the softer parts. This difference in the com- 

 position of butter fat is one cause of the variation in temperature 

 at which cream churns satisfactorily at different times. By 

 churning, the fat globules are made to adhere to each other, be- 

 ginning with the microscopic drops which gradually accumulate 

 and stick together until the mass becomes large enough to be 

 seen, and finally to form granular butter. The point at which the 

 fat globules begin to stick together varies according to the com- 

 position of the fat and its temperature; pieces of tallow need to 

 be warmer than pieces of lard in order to make them stick to 

 each other, and if both are heated so high as to melt and become 

 oily, such particles would break apart and fail to stick together 

 when brought into contact with each other by churning. This 

 property of tallow and lard to become sticky and adhesive at 

 different temperatures illustrates the differences in churning that 



