3QO MICROBIOLOGY OF SPECIAL INDUSTRIES. 



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

 tion 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 silks are removed and 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 off particles of the cob with the 

 corn. After the corn is cut off the cob, some canners add a "syrup" of water, salt, and 

 sugar, and cook the corn for a few minutes at a temperature of 80, after which it is filled 

 into 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 tempera- 

 ture employed varies somewhat, but usually lies between 110 and 120 for thirty 

 minutes for pints. Proportionately longer time is required for larger packages. 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 temperature, 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 on to 

 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 pad- 

 dles or beaters so arranged that as the vines pass 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. They are next graded for quality. This is 

 accomplished by passing them through tanks containing salt solutions of different 

 densities. The first grade includes all peas which will float in a salt solution having a 

 specific gravity of 1.040. The second grade consists of all peas which will float in a solu- 

 tion of specific gravity 1.070, while the third grade consists of peas which will sink in 

 the latter solution. Grading for size is next done by passing the peas over sieves, or into 

 a revolving cylinder having four sections with perforations of different sizes. The small 

 peas are of the best quality, and the quality decreases as the size of the peas increases. 

 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 one minute to five or more minutes, large mature peas requiring longer 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 considerably, the average being 

 115 for twenty-five to forty minutes for the ordinary sized can. 



Fruits. The essentials in the canning of fruits do not differ from those for vegeta- 

 bles. Stone fruits may be canned either with or without the pits. In case of such fruits 

 as cherries, or other acid fruits, the tin container must be coated on the inside with some 

 substance which will protect the tin from the galvanic action of the juice, which when 

 it occurs causes a deterioration in color of the fruit. The time and temperature of 



