LETTER OF TRANSMITTAL.
U. S. Department of Agriculture,
Bureau of Chemistry,
Washington, D. C., July 15, 1908.
Sir: I have the honor to submit for your approval a report made by Inspector Bitting of experimental work on the spoilage of tomato ketchup, the conditions contributing thereto, methods of prevention, the action of preservatives, and the length of time that the product will keep under varying conditions of manufacture and temperature, both before and after opening. Every effort has been made to conduct the work in a practical way, and the results obtained can not fail to be of interest and profit both to the manufacturer and consumer. I recommend that this report be published as Bulletin No. 119 of the Bureau of Chemistry.
Respectfully, H. W. Wiley,
Chief.
Hon. James Wilson,
Secretary of Agriculture.
CONTENTS.
| Page. | |
| Introduction | [7] |
| Process of manufacture | [8] |
| Selection and preparation of stock | [9] |
| Pulping | [9] |
| Cooking and seasoning | [10] |
| Evaporation and finishing | [11] |
| Bottling | [11] |
| Processing | [11] |
| Character of products | [12] |
| First-class products | [12] |
| Inferior products from “trimming stock” | [13] |
| Labels | [14] |
| Manufacturing experiments without the use of preservatives | [15] |
| Outline of experiments | [15] |
| Discussion of results | [17] |
| Spoilage of ketchup after opening | [17] |
| Spoilage of unopened ketchup | [20] |
| Spoilage of market brands | [20] |
| Sterility of ketchup | [21] |
| Experiments with preservatives | [22] |
| Sodium benzoate | [22] |
| Salt | [23] |
| Sugar | [23] |
| Spices | [24] |
| Water infusions | [24] |
| Acetic acid extracts | [25] |
| Oil extracts | [25] |
| Vinegar and acetic acid | [26] |
| Oil | [27] |
| Study of Penicillium in ketchup | [28] |
| Development | [29] |
| Reproduction | [29] |
| Growth in ketchup | [30] |
| Temperature tests | [31] |
| Histological structure of ketchup | [33] |
| Microscopical examination of some commercial brands | [34] |
| Summary | [35] |