244 



CONDSNS^D MILK: 



the fresh milk is subjected in the forewarmers and before it 

 reaches the vacuum pan. The thermal death point of all forms 

 of yeast which have come to the attention of the writer in con- 

 nection with a vast number of investigations of fermented con- 

 densed milk was below 180 degrees F. If all the milk is properly 

 heated in the forewarmers to 190 degrees F. or over, there is, 

 therefore, little danger of fermented milk, caused by contamina- 

 tion of the fresh milk on the farm with yeast. If, however, the 

 heating is incomplete, or if some of the milk passes into the 

 vacuum pan without having been properly heated, there is dan- 

 ger of milk, contaminated with these yeasts, to result in fer- 

 mented condensed milk. 



Contamination with Yeast in the Factory. As previously 

 stated, veast fermentation of condensed milk can almost in- 



$., 



\ 



Fig*. 85. Gaseous fermentation in 

 sweetened condensed milk 1 



Fig-. 86. Yeast cells causing 

 gaseous fermentation 



This species is capable of 

 fermenting sugar solutions 

 containing 85% sucrose. 1 



variably be traced back to contamination in the factory. After 

 the milk leaves the forewarmers, or hot wells, it is never again 

 heated to temperatures high enough to destroy these destructive 

 yeast cells. The channels through which yeast contamination 

 may occur in the factory are many. 



1 Hunziker, A Study of the Causes of Fermented Sweetened Condensed 

 Milk, 1910. 



