STUDY OF PENICILLIUM IN KETCHUP. 31 



acid media had the same appearance as those developed on ketchup, 

 but had a smoother outline. 



TEMPER ATTIRE TESTS. 



The limits for the germination of Penicillium, as given by W. J. 

 Sykes," are 2 to 43 C. (35 to 110 F.), and the most favorable 

 temperature 22 to 26 C. (72 to 79 F.). This author states also 

 that according to Pasteur the dry spores retained their vitality at 

 108 C. (226 F.), but that they were soon killed when immersed in 

 boiling water. Klocker 6 quotes Pasteur as saying that the conidia 

 are killed if exposed to a temperature of 127 to 132 C. for half an 

 hour, but that they retain life at 119 to 121 C. 



A series of tests was made to determine the thermal death point of 

 the moist and dry conidia of the Penicillium used in the experiments, 

 a young, vigorous development on ketchup being used. The flasks 

 were kept under observation for a month after the tests were made, 

 as in many cases a development does not occur in the usual time. 

 The high temperatures applied for longer periods of time were tried 

 first, but both temperature and time were reduced as results from the 

 series were obtained. Only the conditions obtaining in the final tests 

 are given in the table. It was found that the Penicillium used did 

 not have the high resistance supposed. 



The tests were made in small flat-bottomed 10-cc flasks, tomato bouil- 

 lon being used for the tests on moist conidia. The bouillon was used 

 so as to have the conidia in a nutritive medium after the test was made, 

 without transferring. The time for those at 1 00 C. was estimated from 

 the time of ebullition. At the end of the specified time, the flasks were 

 cooled promptly under running water. As the flat bottoms gave com- 

 paratively large surface, the heating and the cooling could be effected 

 in a short time. For the tests below 1 00 C . a vessel of water was heated 

 to the desired temperature, and the flasks were immersed in it and 

 shaken constantly. The dry conidia were placed in test tubes which 

 were immersed in boiling water for the desired time and cooled under 

 running water, after which 10 cc of sterilized tomato bouillon was 

 added. After determining the death point in this manner and finding 

 it to be much lower than had been supposed, it was decided to make 

 the test again, but using ketchup as the medium. Ten grams of 

 ketchup were sterilized, then inoculated from a vigorous growth of 

 mold, and tested with a set in which the tomato bouillon was used. 

 For those below 100 C. the two flasks which were to receive the same 

 temperature were held in the vessel of water at the same time, so that 



Principles and Practice of Brewing, 1907, p. 284. 

 &Ibid., p. 281. 



