BULLETIN 303, U. S. DEPARTMENT OF AGRICULTURE. 



THE NUMBER OF BACTERIA. 



Numerous samples of ice cream were purchased from various stores 

 in Washington during the summer and winter season; they repre- 

 sented 24 different manufacturers. 1 Samples representing 11 plants 

 were examined during both seasons. The ice cream from 5 manu- 

 facturers was examined during the summer season only, and from 7 

 plants during the winter season only. In Table 2 are shown the total 

 (average of the two kinds of samples) average counts of ice cream 

 from each plant, together with the average of the samples collected 

 during the summer and winter seasons. It will be seen that only 

 two plants, Ki and P, out of the 24 showed an average bacterial 

 content of less than 1,000,000 per cubic centimeter. It is possible 

 that if more than one sample had been examined from plant P the 

 average count for that plant would have been more than 1,000,000. 



Table 2. — Average number of bacteria per cubic centimeter in ice cream from different 



manufacturers. 



Manufacturer. 



All samples. 



Summer series. 



Winter series. 



Total 

 samples. 



Average 

 bacteria per 

 cubic centi- 

 meter. 



Number 



of 

 samples. 



Average 

 bacteria per 

 cubic centi- 

 meter. 



Number 



of 

 samples. 



Average 

 bacteria per 

 cubic centi- 

 meter. 



A 



32 

 27 

 19 

 11 

 9 

 8 

 12 

 5 

 8 

 3 

 4 



12 

 4 

 4 

 3 

 6 

 1 

 2 

 1 

 3 

 4 

 2 

 3 

 3 



2,986,187 



32,007,500 



27,779,631 



18,836,363 



44,783,333 



5,381,500 



2,580,250 



4,203,600 



15,487,500 



5,890,000 



265,750,000 



357.583 



32,225,000 



10, 910, 000 



5,723.333 



46,465,000 



920, 000 



19,750,000 



20,500,000 



2,463,333 



3,650,000 



28,500,000 



14,700,000 



17,566,666 



19 

 10 

 11 

 8 

 3 

 3 

 5 

 4 



I 



4 

 4 

 4 

 4 

 3 

 6 

 1 



5,008,333 



31,226,000 



47,909,090 



26,125,000 



118,000,000 



8,966,666 



6,192,500 



5,207.500 



18,360,000 



14, 100, 000 



265,750,000 



530,000 



32,225,000 



10,910,000 



5,723,333 



46,465,000 



920,000 



13 

 17 

 8 

 3 

 6 

 5 

 7 

 1 

 3 

 2 



416,000 

 47,763,529 



101,000 

 6,066,666 

 8,175,000 

 3,230,400 

 1,160,428 



188,000 



10,700,000 



1,785,000 



B 



C 



D 



E 



F 



G 



H 



I 



J 



K 



Ki« 



8 



271,375 



L. 



M 







N 







O 



P. . 











Q 



2 

 1 

 3 

 4 

 2 

 3 

 3 



19,750,000 

 20,500,000 

 2,463,333 

 3,650,000 

 28,500,000 

 14,700,000 

 17,566,666 



R 



S 











T . 







U.. 







w 



X 

















i Ki same plant as K, but there was probably a change in management. 



An interesting point is shown in the bacterial averages of ice cream 

 from manufacturers K and K x . The average bacterial content of 

 ice cream from K was 265,750,000, and from K t 357,583 per cubic 

 centimeter. These represent the same plant, but in all probability 

 there was a change in management. We are not certain of this 

 point, but after the four samples were taken from K the condition 



1 Throughout this paper reference is made to samples from different manufacturers or plants, but it must 

 be remembered that the samples were obtained from stores and not at the plants. 



