Sweetened Condensed Milk Defects 213 



Relation of Polluted Water to Rancidity.— Polluted and filthy 

 water is usually contaminated with fungi and bacteria belonging 

 to the species enumerated above and which have been found to 

 be able to produce rancidity. It is, therefore, not improbable, 

 where such water is used in the factory in the washing of cans, 

 conveyors, kettles, pipes, etc., in the condenser of the vacuum 

 pan and in the cooling tanks, as is frequently the case, that the 

 contamination of milk with it may result in the development 

 of rancidity. 



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 viola- 

 tions 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 conformance with the law, and containing all 

 the butter fat of the original whole milk, does not turn rancid 

 at any temperature. 



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 de- 

 grees 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 decompos- 

 ing the proteids. The 'action of most of these enzymes is 

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



