468 STATE BOARD OF AGRICULTURE 



cause not a flat sour but a swell. Some of the checks, however, both un- 

 pened and opened, also swelled. 



There seemed to be more spoilage in the opened than in the unopened 

 checks. Two explanations may be offered for this occurrence and it would 

 be extremely difficult to prove which was right. Either organisms were intro- 

 duced accidentally on opening the can through the drawing in of air when the 

 vacuum is destroyed or the destruction of the vacuum allowed the entrance 

 of air thus encouraging organisms alreadj^ present and dormant which needed 

 a certain amount of air for growth. This latter explanation is the more 

 probable and covers the conditions in the 37° checks also. 



So far as the records show, there is more spoilage in the 37^ cans than in 

 the 20° cans, and what is more interesting, there is more spoilage in the 55° 

 cans than in the 37° cans. This suggests either that the optimum for the 

 organisms introduced lies nearer 55° than 37°, or that thermophiUc bacteria 

 (not the ones introduced as these are not true thermophiles) are hard to kill 

 by the ordinary processing methods and that they remain dormant under 

 ordinary methods of storage. 



The conclusions may be drawn at this time : First, that cans after processing 

 should be cooled as rapidly as is consistent with the type of container, and 

 then that the storage temperature be below 20° if possible. 



The 55° degree cans were opened in March, 1921, one year following inocu- 

 lation, cultured and studied since these data were desired as an addition to 

 the data on thermophiles already accumulated. Due to lack of time the 37° 

 and 20° cans were not opened until August, 1922. 



All of the cans were treated as follows: the tops were washed with 1-500 

 mercuric chloride, a hole large enough for inserting an inoculating needle was 

 punctured in the top near the edge, the presence of gas being noted at the 

 time; then two cultures were made, one a shake in plain dextrose agar under 

 oil for high temperature cultivation, and the other a shake-slant in dextrose 

 agar plus brom thymol blue for 37° incubation. The top was then removed 

 and the color, appearance, odor, consistency and pH of the contents noted. 



