PASTEURIZING MILK. 



13 



Table 2. — Comparison of bacterial reductions in milk pasteurized in unsteamed 

 bottles and in pasteurized millc bottled ivliile hot in steamed bottles. 





Raw milk 

 (bacteria 

 perc. c). 



Milk pasteurized at 145° F. for 30 minutes. 



Sample No. 



Hot pasteurized milk 

 in hot steamed bot- 

 tles. 



Milk pasteurized in 

 washed but un- 

 steamed bottles. 1 





Bacteria 

 per c. c. 



Percentage 

 reduction. 



Bacteria 

 per c. c. 



Percentage 

 reduction. 



2. 



58,000 



63, 000 



5, 100, 000 



580, 000 



5,900,000 



99, 000 



7, 400, 000 



191,000 



14, 100, 000 



24,700 



75, 000 



126, 000 



4,100,000 



76, 000 



8, 100, 000 



18, 900 



24,000 



28, 300 



80,000 



160,000 



151,000 



81,000 



1,160 

 220 

 8,400 

 8,300 

 6,000 

 610 

 6,300 

 2,000 

 7,000 

 4,550 

 3,000 

 1,440 

 2,470 

 1,400 

 1,620 

 760 

 800 

 7,050 

 1,360 

 1,830 

 3,200 

 6,800 



98.00 



99.65 

 99.83 

 98.57 

 99.90 

 99.38 

 99.91 

 98.95 

 99.95 

 81.58 

 96.00 

 98.86 

 99.94 

 98.16 

 99.98 

 95.97 

 96.66 

 75.09 

 98.30 

 98.86 

 97.88 

 91.60 



1,630 



1,070 



11,800 



8,000 



15,600 



980 



7,100 



7,600 



14,200 



5,780 



28,000 



1,720 



2,410 



3,550 



1,660 



710 



10, 900 



23,300 



2,010 



29,500 



12,500 



9,800 



97.18 



3... 



98.30 



4... 



99.76 



5 . 



98.62 



6 



99.74 



7... 



99.01 



8... 



99.90 



9.. . 



96.02 



10 



99.89 



11 



75.59 



12 



62.66 



13 



98.63 



14 



99.94 



15 



95.32 



16 



99.98 



17 



96.24 



18 



50.41 



19 



17.67 



20 



97.48 



21 : 



81.56 



22 



91.72 



23 



87.90 









2,115,268 



3,467 



96.50 



9, 0S3 



88.34 







1 Bottles were washed clean in hot water, but not steamed, before they were filled with raw milk. 



The results of the bacteriological examinations are shown in Table 

 2. It will be seen that the average count of the raw milk was 2,115,- 

 268 bacteria per cubic centimeter. After being pasteurized in bulk 

 and bottled hot in hot steamed bottles the average count was 3,407 

 bacteria per cubic centimeter, while the average count when pas- 

 teurized in bottles was 9,083 bacteria per cubic centimeter. Compar- 

 ing the percentage of bacterial reductions, it will be noted that the 

 average reduction of the milk bottled hot was 90.50 per cent and only 

 88.34 per cent in the milk pasteurized in bottles. In 19 of the 22 

 samples the bacterial count was lower in milk pasteurized in bulk and 

 bottled hot. In many cases the count was much lower, as may be seen 

 by comparing samples 4, 0, 7, 12, and 18. This difference is. par- 

 ticularly striking in sample 21, in which milk pasteurized in bulk 

 and bottled hot showed a count of 1,830, and some of the same milk 

 pasteurized in a bottle for the same time and at the same temperature 

 contained 29,500 bacteria per cubic centimeter. 



In the belief that this marked difference might be due to the fact 

 that the bottles were steamed in the first case and unsteamed when 

 the milk was pasteurized directly in bottles, another series of samples 

 was pasteurized in which both bottles were steamed for two minutes 



