36 EXPERIMENTS ON THE SPOILAGE OF TOMATO KETCHUP. 



conducted was used, but other recipes could be adapted without 

 changing the character of special brands. In the manufacture of 

 such a product the following precautions were observed: 



(a) Whole, sound, ripe tomatoes and high-grade salt, sugar, vinegar, 

 and spices were used ; care and cleanliness were observed at every step 

 of the preparation, and the preservation accomplished by heat in the 

 following manner: The pulp was cooked in a steam kettle for about 

 forty minutes, until the mass was reduced to about one-half its vol- 

 ume. Additional processing after bottling did not appear to be 

 necessary to keep the ketchup before opening, and had no effect in 

 these experiments in delaying spoilage after opening. 



(&) Ketchup was bottled directly from the cooker at a temperature 

 of 205 F. in bottles prepared in two ways: (1) Sterilized in a steam 

 chamber at 230 F; (2) Washea in hot water, rinsed, and heated to 

 190 F. in a dry heat for at least thirty minutes. Ketchup was also 

 bottled after the usual process of sieving at 165F. in bottles prepared in 

 a similar manner. The corks for all bottles were sterilized in a paraffin 

 bath at 270 F. The same ketchup which was bottled at 165 F. was 

 also given subsequent processing at 190 F. and 212 F. for twenty 

 and forty minutes. All have kept without spoilage. 



3. Some of the condiments have a limited antiseptic value, but can 

 not be depended upon to prevent spoilage in the quantities used for 

 flavoring. While sugar and vinegar can be added in such amounts as 

 to delay the appearance of molds, and cinnamon and cloves can be 

 depended upon to check deterioration to some extent, these condi- 

 mental substances have only an incidental value for this purpose. 



4. The spoilage of ketchup after opening depends more upon the 

 temperature of the place in which it is kept than on any variation in 

 the manner of processing. Fresh ketchup held, after opening, at a 

 temperature of 95 F. kept for five days on an average without any 

 trace of mold appearing; at 72 it kept for six days; at 67 for eight 

 days; about 46 (refrigerator), fourteen days; and at from 30 to 60 

 for twenty-seven days. These figures represent the time at which the 

 first trace of spoilage occurred in the neck of the bottle had this been 

 removed the figures would be much increased and by no means 

 represent the maximum time during which the ketchup could have 

 been used, the maximum figures, even under these conditions of obser- 

 vation, varying from eight to fifty-eight days. The keeping of the 

 ketchup in warm storage at 70 for one hundred and fifty days before 

 opening hastened the average time of spoilage after opening about 

 one day. The advisability of using small containers, to get the best 

 results with a first-class ketchup, is apparent. 



5. Sodium benzoate, even when used in the proportion of 0.1 per 

 cent, is not always effective, and has an injurious effect upon the 



