526 MICROBIOLOGY OF FOODS 



FROM STANDPOINT OF COMMERCE. In its commercial aspect, the 

 importance of the industry can scarcely be estimated. 'Canned 

 products make possible the carrying of larger stores of provisions by 

 armies and navies and expeditions for exploration than would otherwise 

 be possible. In fact, the stimulus which prompted the investigation of 

 Appert was a prize offered by the French Navy Department for a 

 method of preserving foods for provisioning ships more satisfactory 

 than pickling, drying, smoking or preserving in sugar, the methods 

 in use up to that time. 



"Although the preserving industry was established in three great 

 commercial centers in the United States as early as 1825, it did not 

 become of much importance until the last decades of the nineteenth 

 century. There were many hindrances to the progress of the industry, 

 such as the secrecy observed in the process, skepticism of the public 

 regarding the healthfulness of canned foods, the general prejudice 

 against them, and the high cost of production. These obstacles have 

 gradually been surmounted, and at the present time the several 

 branches of the industry have collectively assumed large proportions. 



An idea of the magnitude and importance of the industry in the 

 United States may be gained from statistics for 1918 compiled by the 

 National Canners' Association, and here reproduced by permission. 

 The pack of tomatoes was 15,882,372 cases; of corn, 11,721,860 cases; 

 and of peas, 10,898,222 cases. The total vegetable pack for 1917 other 

 than corn, peas, and tomatoes, was 13,391,294 cases, and of fruit was 

 11,285,659 cases. The average case holds two dozen cans. These 

 figures do not include the pack of oysters, meats, or fish. The total 

 annual consumption of canned foods has been estimated at 250,000,000 

 cases. It is apparent from these figures that the canning and preserv- 

 ing industry is one of immense value, and that it constitutes a large 

 factor in the feeding of the world. 



ALTERATION OF FOOD 



PHYSICAL CHANGES. Appearance. Some physical changes attend 

 the conservation of foods by heat, approaching more or less closely the 

 changes incident to the ordinary preparation of fresh foods for the 

 table. In the preserving of some fruits and vegetables the canner 

 subjects them to a blanching or fore-cooking process which consists in 

 submitting the product to the action of hot water for a short time. The 



