466 MICROBIOLOGY OF SPECIAL INDUSTRIES 



meats. On account of its proneness to rapid decomposition, especial care must be 

 observed that the fish are in a perfectly fresh state before canning, and that the 

 sterilization be most thorough. Salmon is the principal fish for the preservation of 

 which dependence is placed on sterilization alone, most fish being preserved by 

 other methods. 



Vegetables and Fruits. Corn. — ^The young tender ears of sweet corn are picked 

 from the stalk, preferably in the early morning, keeping the husks on, and are 

 taken in this condition to the factory. They are husked and the sUks removed ahd 

 passed through machines with sets of knives which cut the grains evenly from the 

 cob, care being observed not to cut the corn so closely as to cut oflf particles of 

 the cob wi^;h the corn. After the corn is cut o£f the cob, some canners add a "syrup" 

 of water, salt and sugar, and cook the corn for a few minutes at 80°, after which it 

 is filled into the cans, sealed, and sterilized. Another method is to fill the uncooked 

 corn directly into the cans, fill them with "syrup," hermetically seal and sterilize. 

 The temperature employed varies somewhat, but usually lies between 115° and 

 121° for thirty minutes for No. 2 cans holding 20 ounces. Proportionately longer 

 time is required for larger cans. Most of the operations are carried on by machinery. 

 The sterilization is sometimes done in the ordinary canners' retort, or the cans may 

 be placed on an endless conveyor, dipping into water or brine of a proper tem- 

 perature, the speed of the conveyor being so regulated that the cans are sufficiently 

 heated to sterilize them during the passage. 



Peas. — In the pea-canning industry the vines are cut with a mower, loaded 

 onto racks like hay, and hauled to the vining machines. The viner is a machine, 

 consisting of an outer and an inner cylinder revolving in opposite directions, the 

 inner one bearing paddles or beaters so arranged that as the vines piss through the 

 machine the paddles break open the pods. As the peas are thrown out, they 

 pass through perforations in the outer cylinder, while the vines are, discharged at 

 the opposite end. The shelled peas are next washed to remove all dirt and also 

 the* mucous substance from the surface, thus insuring a clearer liquor in the can. 

 Grading for size is done by passing the peas over sieves, or into a revolving cylinder 

 having four sections with perforations of different sizes. The peas are next blanched 

 in hot water to remove the mucous covering and to drive water into the peas so 

 that all will be tender. The time of blanching varies from one-half to five or more 

 minutes, large mature peas requiring niore time for the blanching than smaller ones. 

 After blanching, the peas are filled into the cans by special machines, the cans are 

 filled with "liquor" consisting of water, salt, and sugar, sealed, and sterilized. 

 The time of processing varies, the average being 1 1 5° f or thirty to thirty-five minutes, 

 for the ordinary sized can. 



Fruits.T—Ths essentials in the canning of fruits do not differ from those for 

 vegetables. Stone fruits may be canned either with or without the pits. In the 

 case of such fruits as cherries, or other acid fruits, the tin can is coated on the inside 

 with a laquer or enamel which protects the tin from erosion by the action of the 

 acid juices. The' time and temperature of processing of fruits is usually less than 

 that required for vegetables, for the reason that in the presence of the fruit acids, 

 the organisms are more easily destroyed than in foods in which acids are not present. 



