STUDIES IN THE BACTERIOLOGY OF THE COLD PACK CANNING 



METHOD. 



RUTH NOBMINGTON. 



In making determinations of the bacteriology of cold packed canned goods, 

 I restricted mj^ work to canned peas, all of which had been heated in the auto- 

 clav at 15 pounds pressure for the time given by the latest government 

 bulletins. 



The peas were canned in two lots, the first consisting of thirteen quarts, 

 which wei'e picked one day, partly shelled, put in the refrigerator, the shelling 

 completed the second day and canned in quart Mason jars. These were heated 

 one hour at 15 pounds pressure. The second lot, consisting of seven one-pint 

 jars, was prepared similarly, except that the peas were not refrigerated over 

 night. Both lots were picked during the hot, dusty weather last summer 

 (1918). 



These cans when examined a month later all showed spoilage by presence 

 of gas and more or less sediment at the bottom of the can. Five cans from 

 each lot were examined. The five from the first lot examined showed leakage, 

 but my findings indicate that these were, in part at least, probably due to 

 the pressure of gas in the cans. Two organisms were found in the first can 

 and three in each of the other four. In the second lot, gas was present but 

 no leakage. Two organisms were isolated from the first can, four from the 

 second, three from the third and fourth, and two from the fifth. Two of the 

 cans had an odor of spoilage ; the odor of the others was practically normal. 



The cans before opening were wiped off with a 1-1000 mercuric chloride 

 solution, then alcohol was poured over the top and burned off. The lid was 

 loosened and lifted, but not removed. Three sets of gelatin agar tubes were 

 inoculated from the can contents, using the loop dilution method, one set being 

 used as shakes, while the other two sets were poured for aerobic and anaerobic 

 plates. The anaerobic plates were placed in a Novy jar filled with hydrogen. 

 All were kept at room temperature since spoilage occurred at that temi)era- 

 ture. Titrations were made of the juice from each can, using phenol'phthalein 

 as Indicator. The acidity varied as follows : 



SET I. • SET II. 



Can 1 076/N Can 1 028/N 



Can 2 086/X Can 2 0:iS/N 



Can 3 082/N Can 3 CSS/N 



Can 4 102/N ^an 4 02r)/N 



Can .5 073/N Can .1 040/N 



Unspoiled peas have an acidity of about .02/N. 



21st Mich. Acad. Sci. Rept., 1919. 



