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The Effect of Preservatives on the Development of 

 Pentcillium. 



By Katheeine Golden Bitting. 



I]i examining ketchup for the organisms present, it was noted that the 

 hyphae of moulds in preserved ketchup were swollen and distorted. In 

 many of the brands of ketchup, the mould present was the common blue 

 mould, PeniciUium. As this mould is apparently omnivorous in habit, 

 thriving and fruiting on many media, has been used in many physiological 

 investigations to determine the nutritive value of many compounds, grows 

 normally in liquid media, and fruits normally in a saturated atmosphere, 

 is regular in its germinative power, and, so far as known, constant in 

 form, it was selected to determine the effect of sodium benzoate, used in 

 varying quantities, on its structure and development. The media used in 

 the experiments were tomato bouillon, tomato gelatin, and tomato pulp, 

 and were selected because the tomato juice and pulp are present in ketchup, 

 and also because they do not alter the toxic properties of the agents used 

 Inward the fungus. Afterwards the condiments used in ketchup were 

 tested and also the ordinary food preservatives, though not so extensively 

 as the sodium benzoate. In these latter experiments tomato bouillon was 

 the only medium used. 



The bouillon was made by adding to a can of tomatoes an equal vol- 

 ume of water, boiling for about half an hour, and then Altering. The 

 filtrate is clear, and a good medium for growth. It has an acidity of ap- 

 proximately .2% calculated as citric acid. For the tomato gelatin. 10% of 

 gelatin was added to the tomato bouillon, cleared with egg, and filtered. 

 The tomato pulp was obtained from a factory, and was made from whole 

 tomatoes. To these media the sodium benzoate was added in the various 

 amounts used in factory practice. Before sterilizing the media, calen- 

 dered paper was tied closely over the cotton plug to prevent the distilla- 

 tion of the benzoate. After sterilization and cooling, the media were 

 inoculated with spores from a vigorously growing culture of the mould. 

 During development, the cultures were kept at room temperature, unless 

 otherwise stated. The method of culture was by moist chambers and flasks 

 for the bouillon and gelatin, and Petri dishes for the pulp. The moist 



