. Cyclopedia of farm crops. Farm produce; Agriculture. 170 THE COMMERCIAL CANNING INDUSTRY the ends of the cans and should always be present in sound cans. If, however, putrefaction or fer- mentative changes take place, in which gases are produced, the ends bulge out, owing to the pres- sure of the gas within, and so may be easily de- tected. Even in no swelling of the cans takes place, skilful can distinguish between good and bad cans by the sound when the cans are struck on the ends. The vacuum is generally pro- duced by filling the cans with the material in a hot condition
. Cyclopedia of farm crops. Farm produce; Agriculture. 170 THE COMMERCIAL CANNING INDUSTRY the ends of the cans and should always be present in sound cans. If, however, putrefaction or fer- mentative changes take place, in which gases are produced, the ends bulge out, owing to the pres- sure of the gas within, and so may be easily de- tected. Even in no swelling of the cans takes place, skilful can distinguish between good and bad cans by the sound when the cans are struck on the ends. The vacuum is generally pro- duced by filling the cans with the material in a hot condition and sealing them immediately. When water-bath sterilization is employed, the cans are sometimes unsealed or punched while hot and the steam allowed to escape, the aperture being closed again at once. Principles involved in canning specific crops. In the canning of fresh vegetables, the raw materials are substances high in their percentage of water and relatively high in carbohydrates, but relatively low in proteid matter. Because of dif- ferences in texture and composition, no hard and fast rules of procedure can be laid down. The details of the processes for various kinds of canned goods cannot be given here, but the general prin- ciples involved in the different classes may be mentioned. In the preparation and preservation of all kinds of canned goods the necessity for cleanliness is evident, since the entire operation is one in which the aim is to prevent bacterial action. Although in the final process absolute sterilization is to be brought about, the length of time necessary to produce this end may be much shortened if care is added in sufficient amount to fill the cans. Unless the freshly cut plant is used, a poor product is obtained, as, on standing, it rapidly becomes with- ered and tough. If not sufficiently " processed " it. Fig. 250. A steam apple-butter cooker. taken to exclude the organisms from external sources. Owing to the preponderance of carbohy- dr
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectagriculture, bookyear
