634 STATE BOARD OF AGRICULTURE. 



recommended a longer processing period at a higher temperature, for 

 canned goods. 



Hite, Giddings and Weakley (21) determined the effect of pressure 

 alone on B. suhtilis. Vegetative forms of B. suhtilis suspended iu dis- 

 tilled water were subjected to pressures of from 20,000 to 100,000 pounds 

 for periods of time varying from a few seconds to 120 minutes. Out of 

 fifty-seven tests B. suhtilis was killed in only seven. 



A pressure of 30,000 pounds was applied at a temperature of 48 to 

 50 degrees C. for a few minutes to several hours, to more than two 

 hundred cans of fruits and vegetables. All the vegetables, which in- 

 cluded corn, peas, beans, beets, radishes and potatoes, promptly spoiled, 

 while not one of more than a hundred cans of peaches which were 

 compressed spoiled. Experiments with other fruits were not so suc- 

 cessful. This pressure (30,000 pounds) was found to give uniformlj'^ 

 good results with fruit juices. 



Zavalla (32) published a book in 1916 on "Canning of Fruits and 

 Vegetables." In Part III, he discusses spoilage, giving a report on two 

 hundred and eighty-five bacteriological examinations of canned foods 

 from six canneries. Nine spore formers were described but not named. 

 Gas was found in cans of peas but these organisms did not form gas 

 in sugar fermentation tubes. 



Dickson (IG) in 1917 investigated an occurrence of botulism on the 

 Pacific Coast, finding B. hotulinus in three cases. He then inoculated 

 canned peas, beans, and corn with B. hotuUnus, heating them at a boil- 

 ing temperature presumably in accordance with Government bulletin 

 directions. These developed gas in three weeks. B. hotulinu^s and B. 

 suhtilis were recovered from the cans. He concluded that the time given 

 in the directions for processing in the Government bulletins is in- 

 sufficient. 



The Department of Agriculture (30) answered this paper by saying 

 that the spores of B. hotulinus are killed by one hour of heating at 175 

 degrees F. and that there is, therefore, no danger from B. hotiilinus in 

 canned foods. It was also stated that the toxin from B. hotulinus is 

 destroyed by boiling a few minutes. However, a warning was given 

 against eating foods showing any signs of spoilage. 



In the bulletin entitled, "Bacteriological Examination of Canned Foods" 

 (1917), A. W. and K. G. Bitting (4) discuss leaks, springers, the 

 jjroper method for opening tin cans for examination, pressure in cans, 

 swells and flat sours, and organisms of spoilage. They determined by 

 experiment that it takes a tin can of peas when undisturbed, over 

 twenty minutes to reach 248 degrees F. Cans are more uniformly 

 heated when agitated. Organisms found were a large lactic acid bacil- 

 lus, a coccus form which produced malodor, and thermophilic forms in 

 appearance similar to Ji. tctanl and B. hotulinus. They stale that a 

 much higher temperature is required to destroy the spores of some 

 organisms than of others. 



Georgia S})ooner Burke (8) states in lier article on "The Effect of 

 Heat on the Spores of B. Botulinus" (1918) that B. hotulinus toxin is 

 destroyed by five minutes of boiling, but the spores are not killed in 

 jars of fruit by boiling for five hours. They will also survive three 

 and one half liours of boiling in an open kettle or fifteen pounds of 

 ]>ressui-e in the autoclave for ten minules. She concluded that ])ressure 

 cooking is the only sure method of avoiding spoilage by B. hotulinus. 



