RENOVATED BUTTER 273 



hollow-bowl, Danish- Weston separator, and the recovered 

 oil added to the main batch. 



Refining the Oil. This clear oil is run into a second set 

 of tanks, or kettles, kept at a constant temperature of 

 about i20F. for several hours. During this time, pure, 

 hot air is continuously pumped through the fat. The air is 

 conducted to the bottom of the kettle through a pipe ex- 

 tending through the oil from the top. This air rises and 

 causes a constant ebullition of the oil. This aeration at a 

 high temperature removes practically all the bad odors and 

 flavors, and leaves an almost tasteless, clear, yellow oil. 



Making the Emulsion. This oil is emulsified with sour 

 milk, in order to reincorporate into it a natural butter 

 flavor and the components of normal butter. For this 

 purpose a quantity of good fresh skim milk is ripened with 

 a commercial culture of lactic-acid bacteria, just as a starter 

 is made in a butter or cheese factory. To this sour milk 

 is added about twice its volume of sweet skim milk; then 

 this mixed milk is added to the molten oil in the ratio of 

 about one part milk to one and one-half parts oil. The 

 milk and oil are mixed and emulsified in a cylindrical tank 

 or kettle in which there is a rapidly revolving dasher. In 

 some factories the emulsion is made in the same kettle 

 in which the renovating process occurred. The mixing is 

 accomplished by passing air through the mixture. 



Crystallizing the Fat. This emulsion is then run into a 

 large vat of water at a temperature of 36 to 46 F., which 

 crystallizes the fat. Even though such a large percentage 

 of milk is present it is all incorporated in the fat crystals. 

 The water shows no trace of milkiness. 



The crystallizing vat is usually placed directly under- 

 neath the bottom of the renovating or mixing kettle. This 

 latter tapers at the bottom to a small mouth. A valve at 



