CONDENSED MlLK DEFECTS 207 



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 danger 

 of milk, contaminated with these yeasts, to result in fermented 

 condensed milk. 



Contamination with Yeast in the Factory. As previously 

 stated, yeast fermentation of condensed milk can almost in- 

 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. 



Contaminated Sugar. The sucrose itself may be contam- 

 inated with yeast. This is frequently the case and especially so 

 if the sugar is exposed to dampness, and if flies, bees, ants or 

 cockroaches have access to it. 



Again, the sugar may reach the milk through a sugar chute. 

 The lower end of the chute is usually located directly over the 

 steaming milk in the hot well. The vapors arising from below 

 may be condensed in the chute, causing its inside walls to become 

 damp, and sugar Avill adhere to the damp surface, forming a 

 crust. If the crust is not removed daily, its contamination with 

 yeast and other dangerous micro-organisms is almost inevitable 

 and whenever this crust peels off and drops into the milk, the 

 contamination may be carried into the finished product, giving 

 rise to gaseous fermentation. 



Contaminated Machinery and Milk Conveyors. Remnants 

 of milk may lodge in the condenser, in the vacuum pan, in the 

 pipes conveying the milk and condensed milk, in the cooling 

 cans or coils, in the supply tank of the filling machine, or the 

 filling machine itself. These remnants are all subject to con- 

 tamination and may become the source of fermented condensed 

 milk. The strictest attention to scrupulous cleanliness and con- 

 tinuous inspection of all parts of conveyors and apparatus which 



