Condensed Milk and Milk Powder 163 



Relation of Adulterants to Rancidity. — It has also been experi- 

 mentally demonstrated that the use, in the process of manufacture, 

 of artificial fats, or commercial glucose developed a distinctly rancid 

 flavor in the finished product. 



Relation of Climate to Rancidity. — It is frequently claimed that 

 condensed whole milk shipped to the tropics turns rancid, owing to 

 exposure of this milk, rich in fat, to a warm climate. Advantage 

 is sometimes taken of this argument, to justify violations of the law 

 by skimming all, or a part of the milk before condensing. This 

 matter has been thoroughly investigated. All experimental results 

 show that sweetened condensed milk, made properly and in con- 

 formance with the law, and containing all the butter fat of the 

 original whole milk, does not turn rancid at any temperature. The 

 available evidence goes to show that sieges of rancid condensed milk 

 are usually the result of the addition to the product of adulterants. 

 When, in the manufacture, nothing but pure milk from healthy cows 

 and the best refined granulated sucrose are used and due attention 

 is given to reasonable cleanliness in the factory, the product is not 

 in danger of becoming rancid. 



Putrid Sweetened Condensed Milk 



General Description. — Sweetened condensed milk is best 

 when fresh. With age it gradually develops a stale flavor which 

 frequently develops into a putrid odor and flavor. 



Causes and Prevention. — The purer the fresh milk and the 

 cane sugar, and the more careful the processor, the longer will the 

 condensed milk retain its pleasant flavor, provided that it is stored 

 at a reasonably low temperature. Age, however, will cause the best 

 sweetened condensed milk to become stale. The appearance of the 

 stale flavor is usually hastened when heating the fresh milk with 

 direct steam ; also, where the fresh milk is not heated to a sufficiently 

 high temperature (below 176 degrees F) the condensed milk will 

 break down rapidly with age, usually developing a putrid flavor and 

 odor. This defect rarely appears where the fresh milk is heated to 

 180 degrees F. or above. This phenomenon is probably due to the 

 presence in milk of active enzymes, such as galactase, gradually 

 decomposing the proteids. The action of most of these enzymes is 

 destroyed when the milk is heated to 176 degrees F. or above. 



