496 iSTATE BOARD OF AGRICULTURE 



Column G of Tables Villa, Vlllb, and VIIIc represents the finished 

 product, the bacteria per c.c. as the mix had been frozen and was flowing^ 

 away from the freezer. By referring to Column G it will be noted that 

 the highest number of bacteria per c.c. is 106,000 and the lowest is 2,500 

 per c.c. This justifies the conclusion that an ice cream of low bacterial 

 content can be made in a sanitary plant from raw materials of high gemi' 

 content when report is made to pasteurization and other sanitary meas- 

 ures. 



CONCLUSIONS 



1. This work confii'ins the conclusions of other investigators that, — 

 Cream, condensed milk and gelatin, the principal raw products going 

 into the ice cream mix, contain many bacteria. 



2. Pasteurizing the ice cream mix at 65. G° C (150° F) for 30 min- 

 utes lowers the plate count, from 94.5 per cent to 09.9 per cent, with 

 an average efiiciency of 98.97 per cent as determined by the plate method 

 described. 



3. Homogenizing the ice cream increases the number of bacteria as 

 determined by the plate method. The increaise may be apparent rather 

 than real. No attempt was made to determine whether it was apparent 

 or real. 



4. Cooling from approximately 60° C. to 10° C. is not effective in- 

 killing all the bacteria since a slight majority of the samples showed an: 

 increase. 



5. Aging at 2° C for 24 hours has a tendency to increase the plate- 

 count as a majority of samples shows. 



6. Freezing with the brine at an average of — 14° C. has a tendency 

 to increase the number of bacteria in ice cream. The recorded increase 

 may be apparent rather than real. 



7. Storage of ice cream at an average of — 20.5° C from one day to 

 three weeks decreases the plate count in the majority of cases. There 

 may be variations in individual samples. 



8. After the mix is pasteurized every subsequent operation has the 

 general tendency to increase the plate count. 



9. It is poissible to make vanilla ice cream on a commercial scale with. 

 a low plate count. 



