154 EVAPORATED MILK MOJONNIER CONTROLLER 



The viscosity test therefore furnishes a measure of the 

 resistance of any given batch of evaporated milk toward steril- 

 izing heat. But in order to enable the operator to correctly 

 interpret the results of this test and to correctly govern his 

 method o'f handling the evaporated milk according to these 

 findings, he should have a clear understanding of the correlation 

 of the several factors that influence this resistance to heat and 

 that affect the viscosity. 



With reference to the direction (increase or decrease of 

 viscosity) in which these several factors influence the viscosity 

 and the tendency to curdle the evaporated milk, the following 

 general facts should be known : 



Factors that Cl. high per cent acid in milk 



increase the vis- 2. low stability of proteins 



cosity and the J 3. high concentration of evaporated milk 



tendency to curdle^ 4. high sterilizing temperature 



the milk j 5. long exposure to sterilizing temperature 



6. high pressure in homogenizer 



1. low acidity in milk 



2. great stability of proteins 



Factors that 

 decrease the vis- 

 cosity and the - 

 tendencv to curdle 



3. low concentration of evaporated milk 



4. low sterilizing temperature 



5. short exposure to sterilizing heat 



6. high temperature in forewarmer 



7. extraneous water in evaporated milk 



8. low pressure in homogenizer 

 ^9. addition of bicarbonate of soda 



The exact quantitative relation of most of these factors to 

 one another and to the viscosity of the evaporated milk has been 

 experimentally determined by Mojonnier Bros. Co. for evapo- 

 rated milk standardized to 7.8 per cent fat and 25.5 per cent 

 total solids as follows: 



A 40 degree retardation or viscosity 'as determined by the 

 Mojonnier viscosimeter corresponds to: 



1. One degree F. in sterilizing temperature at the holding 

 point of 240 degrees F., when held for 15 minutes and with the 

 same "coming-up" time as given under "Sterilizing the Five 

 Sample Cans." This means that each degree F. above 240 de- 



