250 SWEETENED CONDENSED MiLk DEFECTS 
enzymes. It 1s, therefore, quite possible that some of these spe- 
cies, or similar groups of species, may be instrumental in develop- 
ing rancidity in sweetened condensed milk. It has been further 
found that the milk products from certain individual cows, or 
cows under certain physiological conditions are more prone to 
develop a rancid flavor, than milk products from other cows or 
cows under other conditions. 
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 im- 
probable, 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 develop- 
ment 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. Al! 
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- 
