J 62 Condensed Milk and Milk Powder 



the milk fats. Formerly these defects were attributed to the break- 

 ing down of the glycerides of the volatile fatty acids, but more recent 

 experimental data indicate that the olein is the most unstable fat, 

 owing to' the ease with which it yields to oxidation, and that the 

 splitting up of the glycerides of oleic acid in all probability is largely 

 responsible for the different shades of rancidity which develop in 

 dairy products under certain combinations of conditions. 



According to the best authorities, there are many agents which 

 may be active in the production of rancidity. The fact that in ran- 

 cid butter are usually found to predominate certain species of organ- 

 isms, such as the fungi of Penicilium Glaucum, Penicilium Roque- 

 forti, 'Cladosporium butyri, Oidium lactis, Actinomycoces odorifora, 

 yeast and various bacterial species, such as Bacterium fluorescens, 

 Bacterium prodigiosum, Bacillus mesentericus, etc., and that these 

 species are capable of making butter rancid, has led to the conclusion 

 that they may be the cause of rancidity, either by direct action, or by 

 the secretion of fat-splitting enzymes. It is, therefore, quite possible 

 that some of these species, or similar groups of species, may be in- 

 strumental in developing rancidity in sweetened condensed milk. It 

 has been further found that the milk products from certain indi- 

 vidual 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. 



Other agents capable of decomposing the glycerides of the 

 various fatty acids, and especially of oleic acid, are heat, air and light. 

 Thus, sweetened condensed milk, similar to butter, when exposed at 

 room temperature to light and air will assume a tallowy and rancid 

 flavor very readily. In cold storage this development is retarded. 

 In the dark, it is very slow and the absence of air also hinders 

 this development. 



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. 



