18 EXPERIMENTS ON THE SPOILAGE OF TOMATO KETCHUP. 



at :i temperature of about 72 F., 5 were kept in an incubator at a 

 temperature of 95 F., 5 were kept in the laboratory at a tempera- 

 ture of about 67 F., and 4 were kept in an inclosed porch where 

 the temperature ranged from 30 to 60 F. This made a total of 

 198 bottles. No precautions, other than those of ordinary clean- 

 liness, were taken in opening the bottles, as it was desired to deter- 

 mine the keeping properties under conditions of general usage. The 

 first set of bottles was opened November 5, immediately on being 

 received at the laboratory, all of the ketchup having been kept at 

 the factory until the experiment begun in September was completed. 

 The bottles were covered loosely with a metal cap and observed daily, 

 a record being kept of the date and character of spoilage. 



The results showed that the differences in the time .and temperature 

 of processing had little, if any, effect in checking the spoilage ; neither 

 did the use of acetic acid or oil extracts. The most important pre- 

 caution in checking the spoilage after opening seems to be to keep 

 the ketchup cool. This is shown by the average number of days 

 which elapsed before spoilage occurred in the sets kept under different 

 temperature conditions. For those kept in the kitchen the average 

 number of days was six, the minimum three, and the maximum 

 eleven. Those in the incubator kept for an average of five days, with 

 a minimum of two days, and a maximum of eight. Those in the 

 laboratory had an average of eight days, the minimum being four 

 days and the maximum twenty-two. Those kept in the porch lasted 

 on an average twenty-seven days, a minimum of twelve days, and a 

 maximum of fifty-eight. 



These figures show the definite relation of temperature to spoilage 

 under the conditions of ordinary use. In making the observations, 

 the metal cap was removed each day, but no ketchup was poured off. 

 The spoilage in all cases was due to mold, and usually this formed in 

 the neck of the bottle where the ketchup had splashed, or at the 

 junction of the ketchup with the bottle. The spoilage was recorded 

 as soon as the slightest growth appeared. In actual use if the neck 

 were wiped out when the ketchup had been used and a growth of 

 mold removed on its first appearance with some of the proximate 

 ketchup the time before spoilage occurred could be prolonged. In 

 these experiments the attempt was made to determine how soon 

 growth appeared under the various conditions of temperature named. 



The unopened bottles of ketchup were kept in a basement room, 

 the temperature of which is fairly constant, being about 70 F. 

 This is approximately the condition in a grocery where the ketchup is 

 kept on the shelves. Another set of samples from the run of Sep- 

 tember, 1907, was opened February 11, 1908, to determine if storing 

 in a warm room before opening had any effect on the length of time 

 preceding spoilage. Four bottles were taken from each of the first 9 

 experiments to make up each of three sets, one of which was kept in 



