CONDENSED MILK 



241 



observed buttons on condensed milk held at 68 degrees F. or 

 below. These temperature limits are not corroborated by exper- 

 iments by Hunziker, nor by the experience of the manufacturer. 

 In commercial manufacture, the storage of sweetened condensed 

 milk at 68 degrees F. will show copious button formation, if such 

 milk contains button-forming spores. Reasonably sure preven- 

 tion of buttons may be secured by holding the sweetened con- 

 densed milk at about 50 degrees F. or below. 



Exclusion of Oxygen. Molds need air for their life and 

 growth. They cannot develop in the absence of oxygen. Accord- 



Pig-. 84. 

 Absence of buttons in 2O-incli 



Pigf. 83. 



Button development tinder 



atmosperic pressure vacuum 



Courtesy of L. A. Rogers, U. S. Dairy Division 



ingly Rogers et al., by careful experimenting, found that by seal- 

 ing the cans under a vacuum of 20 inches or more, button-for- 

 mation in condensed milk contaminated with button-forming 

 molds could be entirely prevented. 



It is probable that a similar effect, if practicable, could be 

 accomplished also by charging the cans with an inert gas to the 

 exclusion of atmospheric oxygen. 



