608 MILK 



amido-nitrogen in butter, and studied bacteria which were able 

 to multiply slowly at 6 C. in salted butter. The authors .are 

 in doubt, however, whether these bacteria cause deterioration. 

 Thorn and Shaw found that molds attack unsalted or slightly 

 salted butter, but rarely affect fully salted butter. Guthrie, 

 after a careful study, declares that chemical changes in butter 

 were slight when biologic agencies were checked. Exposing but- 

 ter and butter-fat to high temperature, light, and air caused no 

 rancidity and no important change in the iodin number. In fact, 

 according to this work, the rancidity of butter ordinarily spoken 

 of, is rare and a strong flavor is frequently mistaken for rancidity. 



In some cheese factories butter is made from the whey, and this 

 is called whey butter. The whey may contain as much as 1 per 

 cent, of fat. Two-thirds of the fat can be saved by allowing the 

 whey to stand for twenty-four hours and then skimming the fat 

 off. A better yield is obtained by boiling the whey and skim- 

 ming the "cream" off the surface. This "cream" contains about 10 

 per cent, fat, while only 0.05 per cent, remains in the whey. This 

 by-product can be utilized to still better advantage if the whey, 

 when it leaves the cheese kettle, is passed through a cream sepa- 

 rator. The separated "cream" is then churned and the product 

 is equal to a good quality of market butter. A good price is 

 realized from this butter, while the whey butter obtained by the 

 first two methods is sold at the price of lard. Doane states that 

 2 to 5 pounds of whey butter can be obtained from 1000 pounds of 

 milk. 



Butter is scored by experts according to flavor, body, color, 

 salt, and style of packing. Michels has defined good butter as 

 follows : 



"Flavor should be rich, pleasing, creamy, and suggest nothing 

 objectionable to either the taste or smell. 



"Body should be firm and waxy. 



"Colqr should be even, showing a luster and an oat straw 

 shade, unless the particular market wants a different color. 



"Salt well dissolved, and just enough to bring out the highest 

 flavor of the butter. 



"Package clean and neat in appearance." 



Off-flavors may be curdy, too acid, rancid, oily or greasy, 

 fishy, stable-taste and odor, bitter, weedy (when cows have been 

 fed on strong-smelling plants), or unclean from ill-kept utensils or 

 poor water. 



The fishy flavor of butter similar to the oily flavor of mackerel 

 or salmon is not uncommon, and has been studied by Rogers. 

 The author says that fishy flavor is caused by a "substance pro- 

 duced by the oxidation of one of the combinations of the acid 



