■ THE DETERMINATION OF B-ACTERIA IN ICE CREAM. 9 



Table III. — Variation in bacterial counts of 9 samples of ice cream taken from each of 

 three 1-gallon lots which had been held in a cabinet for 11 days. 



Plant 

 No. 



Sample 

 No. 



Dilution. 



Number of colonies 



on duplicate 



plates. 



count 

 per c. c. 



Variation between lowest and 

 highest counts. 



50 



46,000 

 47,500 

 46,000 

 48,000 

 38,000 

 44,500 

 51,000 

 43,500 

 43,000 



Samples 5 and 7, 34.21 per cent. 



108 

 111 

 112 

 142 

 132 

 127 

 136 

 130 

 138 



134 



152 

 113 

 149 



186 

 149 



1,080,000 

 1,180,000 

 1,120,000 

 1,380,000 

 1,420,000 

 1,200,000 

 1,425,000 

 1,480,000 

 1,435,000 



Samples 1 and 8, 37.03 per cent. 



690,000 

 645,000 

 685,000 

 650, 000 

 740,000 

 710,000 

 685,000 

 660,000 

 690,000 



Samples 2 and 5, 14.73 per cent. 



Keeping in mind the normal variation in bacterial counts, as indi- 

 cated in Table II, we do not believe that the results warrant the con- 

 clusion that there is any great uneven distribution of bacteria in ice 

 cream, even when held under the extreme conditions of this experiment. 



VARIATION WHEN HELD IN STORAGE. 



In order to determine the effect of cold storage upon the distribu- 

 tion of bacteria in ice cream, three 1-gallon cans were filled with ice 

 cream from the same freezer. Of these, one was examined while 

 fresh, one was held in cold storage in a hardening room at a plant 

 for one month, and the third was similarly held for two months. 



The results of this experiment, recorded in Table IV, show that 

 there was no increase in the variation among the samples from each 

 gallon lot, even after two months' storage. The samples as a whole 

 checked remarkably well, showing nothing to indicate any marked 

 uneven distribution of bacteria. 



