80 THE STOKY OF MILK 



with ordinary care, and in cold storage it may be kept 

 a year. But when it comes out of cold storage it must 

 be used within a few weeks, for butter, like other cold 

 storage foods, will soon spoil and become rancid when 

 it is exposed to a higher temperature for any length of 

 time. 



Renovated Butter. — Butter that has become old and 

 rancid can be ''renovated." The butter is melted and 

 the butter-oil washed, — aerated in the renovating 

 plants,— and then churned with fine-flavored sour skim 

 milk. From the sour skim milk it gets back its old 

 butter flavor. The granular physical consistency of 

 fresh butter is gained by pouring the emulsified mixture 

 over cracked ice or into ice water. By the time the 

 excess of "buttermilk" has been removed by working, 

 and salt has been mixed in, the renovated butter may 

 be almost as good as fresh creamery butter. 



Oleomargarine or Butterine is made in much the same 

 way. A mixture of beef-fat (the soft part of beef- 

 tallow) and lard and cottonseed oil is churned with 

 sour milk and worked and granulated like renovated 

 butter. For the better grades, some of the finest 

 creamery butter is mixed with it, so that the mixture 

 can hardly be distinguished from real butter. 



Coco-butter, Nut-butter, etc., in great variety, are now 

 also on the market as substitutes for butter, all pre- 

 pared in a similar way, but lacking the vital unknown 

 element that makes genuine butter so superior to 

 substitutes. 



BUTTERMILK 



If the cream has been carefully ripened, with or 

 without a pure culture starter, and it has shown the 



