56 DAIRYING 



about 30 per cent, fat, 10 per cent, starter is usually sufficient. The 

 cream and starter are thoroughly mixed and held at nearly 70 F. 

 for four to six hours, or until about .5 per cent, acid has developed. 

 At this point the ripening may be carried further than is safe in 

 raw cream, because in the pasteurized cream the starter is supposed 

 to contain nothing but desirable bacteria, and hence the products 

 they will form by continued ripening should not be so injurious 

 to the butter flavor as is the case with raw cream, because of the 

 variety of bacteria present and the uncertainty as to what products 

 will be formed and taken up by the butter during the ripening 

 process. 



497. When the cream has reached 0-5 per cent, acid it should 

 be cooled to near 50 F. and held at this temperature for two hours 

 at least, or until churned. It is often held from eight to ten hours 

 after cooling begins. 



While cooling, the cream should be thoroughly mixed, and 

 when the cooling has once begun it should progress rapidly until 

 the lowest possible temperature is reached. If the cream* is not 

 cooled to a temperature that will check the growth of bacteria, the 

 ripening process will continue and may go so far as to spoil the 

 butter. It is therefore important that the cooling should be done 

 quickly and the cream kept cold until churned. The ripening of 

 pasteurized cream is subject to the same influences, such as rich- 

 ness and temperature of the cream and condition of the starter, as 

 is described under raw cream ripening. These points need to be 

 watched and provided for as carefully in one case as in the other, 

 but the pasteurized cream ripening has the advantage of being more 

 under the control of the butter-maker than is usually the case with 

 raw cream. 



PASTEURIZING GATHERED CREAM 



498. The cream churned at a gathered cream factory is very 

 often tainted and more or less sour when it is received. This con- 

 dition is usually due to the lack of proper care at the farms and to 

 the age of the cream when collected. It is rarely gathered daily, 



