Читать книгу The Manufacture of Tomato Products - W. G. Hier - Страница 19

For tomatoes grown on clay ground the cylindrical rotary washer or squirrel cage type made of 1–inch mesh heavy wire is very satisfactory. When tomatoes come to the plant caked with clay, as they are after a hard rain followed by strong sunshine, a friction washer of this type is about the only thing that will clean them. This type of washer also does excellent work on late tomatoes, and this applies to all localities. A large percentage of late tomatoes become deeply cracked at the stem end, and although these cracks, or fissures, usually appear to be healed over, an examination will generally reveal the presence of mold in them, and in many cases large tufts of mold like cotton completely filling them. By merely passing such tomatoes through a water bath, even though the water is thoroughly agitated by means of many inlets of compressed air, this imbedded mold will be scarcely affected. A rotary, heavy wire, reel washer, inclined at an angle of about 1 foot in 8, and rotating slowly, with a heavy, sharp spray of water striking the rolling tomatoes from the time they are dumped in until they roll out, will take out a very large proportion of this mold, besides cleaning the entire surface of the tomato thoroughly.

The washer should deliver about two bushels of tomatoes per minute to the sorting belt. As the wire cylinder revolves, the tomatoes are carried half way up the side and are then thrown back again, being carried slowly and steadily toward the outlet. A 1½-inch pipe at the top of the cylinder, and running from end to end, with small holes bored at intervals of an inch, should direct a sharp, cutting shower of water on the tomatoes as they revolve and rub each other. A fine, sharp spray will accomplish more than a less forceful but larger stream of water coming from a larger opening. The dirt, mold, etc. is washed through the wire mesh into a drip pan, and thence to the sewer.

Some of the rotary washers used are of solid metal, and others constructed of wooden slats have been used. Both of these should be avoided, as the solid metal produces a sliding, instead of a rolling action, and the wooden slats mold quickly and become slimy. Also, some of the washers are slightly too narrow, and the tomatoes are so crowded while they are rotating that many of them do not come in contact with the wire, but merely roll on top of other tomatoes. Other washers are considerably wider than necessary. If the tomatoes are to be fed to the belt at the rate of 2 bushels per minute, a reel (squirrel cage) washer 2 to 2½ feet in diameter, and about 8 feet long, having an inclination of about 1 foot in 8, and revolving at about 20 revolutions per minute, will usually give satisfactory results. These are the figures recommended by Mr. Howard of the Bureau of Chemistry, who has made a very extensive study of the efficiency of rotary washers.

By having the tomatoes thoroughly clean, with no mud and scarcely any mold adhering to the surface when they drop on the sorting belt, the amount of sorting required is not only greatly lessened, but the spots of black rot and other forms of decay show up prominently on the surface.

It is important that the reel deliver the tomatoes to the sorting belt at a uniform rate, which is seldom done when the crates are dumped into the reel without any system of timing them. At present a hopper for feeding the reel is being experimented with, and it is hoped that it will be an improvement over the uncontrolled system that is now used.

The chief objection made to the reel cylinder is that when tomatoes are overripe, having been shipped a long distance, or held at the factory for a day or two, the rubbing action of the wire on the tomatoes, and of the tomatoes against each other, is too severe, and considerable tomato substance is lost by being forced down through the wire mesh by the sharp sprays of water from overhead. The loss in this case is not nearly as great as would be imagined, and what tomato substance is thus lost should be discarded anyway, as it is so soft that in all probability the fiber is permeated with growths of mold, yeasts, and bacteria, which no amount of washing would eliminate.