BACTEKIOLOGICAL STUDY OF EETAIL ICE CREAM. 5 
of the store was much improved as regards cleanliness, the ice cream 
no longer contained gelatin, and the bacterial count dropped in a 
remarkable manner. 
When the bacterial averages of the two kinds of samples (summer 
and winter) are compared it may be seen, by reference to Table 2, 
that of the samples from 11 plants the bacterial counts averaged 
decidedly lower during the winter months in every case with the 
exception of plant B. In that case the average winter count was 
higher than that of the summer season. Assuming cream to be the 
greatest source of bacteria in ice cream, we should expect to find the 
bacterial content of ice cream higher during the summer months. 
This is probably explained by the lack of proper facilities on the farm 
for keeping cream cool during the summer, and also by the fact that 
owing to the increased demand for ice cream during the summer 
season poor grades of cream are utilized. In the case of plant B, we 
have no explanation for a higher average bacterial count in winter 
than in summer unless the cream was aged at the plant for a con- 
siderable time at temperatures not sufficiently low to prevent bacterial 
growth. 
In order to show more clearly the comparison of the bacteria in ice 
cream during the summer and winter seasons, the samples have been 
grouped in classes according to their bacterial content, as shown in 
Table 3. 
Table 3. — Comparison of bacterial content of summer and winter samples of ice cream. 
Bacteria per cubic 
centimeter. 
Summer. 
Winter. 
Number 
of 
samples. 
Per cent. 
Number 
of 
samples. 
Per cent. 
to 50,000 


9 
9 
16 
12 
• 13 
10 
8 
9 
8 


9.57 
9.57 
17.03 
12.77 
13.83 
10.64 
8.51 
9.57 
8.51 
5 
8 
23 
2 
21 
5 
11 
5 
3 
4 
4 
5.49 
8.79 
25.27 
2.20 
23.08 
5.49 
12.09 
5.49 
3.30 
4.40 
4.40 
50,001 to 100,000 
100,001 to 500,000 
500,001 to 1,000,000 
1,000,001 to 5,000,000 
5,000,001 to 10,000,000 
10,000,001 to 20,0^0,000 
20,000,001 to 30,000,000 
30,000,001 to 50,000,000 
50,000,001 to 100,000,000 
Over 100,000,000 
Total 
94 
100. 00 
91 
100. 00 
It may be seen that of 94 samples examined during the summer 
months, none contained fewer than 100,000 bacteria per cubic centi- 
meter, while of the 91 samples examined during the winter season, 
14.28 per cent were lower than 100,000. Of the summer samples, 
9.57 per cent contained fewer than 500,000 per cubic centimeter, and 
of the winter samples 39.55 per cent contained fewer than this number. 
Of the summer samples 19.14 per cent contained fewer than 1,000,000 
