SPOILAGE OF UNOPENED KETCHUP.
Another test was made to determine whether the ketchup would spoil when kept in a warm place, but not opened. Three bottles from each experimental batch were placed in the incubator November 7, 1907, and were kept there until December 23, 1907—forty-six days—and in that time there was no sign of spoilage. They were then opened and kept in the laboratory; the average number of days before spoilage occurred is indicated in the following table:
Average number of days before spoilage of ketchup after opening (kept 46 days at 95° before opening).
| Experiment No. | Days before spoilage. |
|---|---|
| 1 | 2⅔ |
| 2 | 4⅔ |
| 3 | 3⅓ |
| 4 | 5 |
| 5 | 5⅓ |
| 6 | 4⅓ |
| 7 | 4⅓ |
| 8 | 4⅓ |
| 9 | 3⅔ |
It will be observed that these samples spoiled in about the same length of time as the bottles opened in February and tested in the incubator, so that similar results were obtained by keeping unopened ketchup one and one-half months at 95° F. and keeping it five months at 70° F. From the results of the experiments it is evident that the ingredients of the ketchup in the proportions used are not antiseptic, and it is also apparent from the number of organisms found and the rapidity of their multiplication that ketchup is a good, nutritive medium. Yeasts and molds are the predominating organisms, and, as the ketchup is acid and also contains sugar, and these organisms are found on tomatoes in the field, their predominance in the ketchup is explained.
SPOILAGE OF MARKET BRANDS.
To determine the keeping properties of the ketchup on the market, various brands were obtained from the grocery stores. In the majority of cases nothing was known of the ingredients or methods of manufacture, except what appeared on the labels. No date of manufacture was given, and in some cases the dealers did not know the age of the product.
There were 104 bottles of ketchup opened to find out how long they would remain in good condition. These were kept in the laboratory, though the temperature was higher than that at which ketchup should be held. Of the 104 bottles there were 66 without preservative, according to the labels, 46 of which spoiled. Of the 20 which did not spoil, 2 formed crystals of benzoic acid on the covers of glass dishes during evaporation. Of the 39 which, according to the labels, contained sodium benzoate, 15 spoiled. The bottles of unspoiled ketchup after remaining in the laboratory for about a month were placed in the incubator at 95° F. for three weeks, and were then taken out, and have been left in the laboratory since. The metal cap had been taken off frequently for observation, and the ketchup exposed, but the treatment did not cause them to spoil.
The average number of days after which spoilage occurred for the 46 bottles without preservative was about fifteen, the minimum number being four days, the maximum number ninety-four days. The average number of days preceding spoilage in the case of 15 bottles with preservative was twenty-four days, the minimum number being three and the maximum sixty days. The majority of these had 0.1 per cent of sodium benzoate present; the others had a smaller amount, according to the manufacturer’s label. These data are not at all conclusive and further work on material of known history will be necessary.