SANITARY CONTROL OF TOMATO-CANNING FACTORIES. 9 



washers, because a thin coating of dirt on the skin of a tomato is 

 less evident when the tomato is wet than when it is dry. Tomatoes 

 that may appear fairly clean when wet may still show a thin, adher- 

 ing coat of soil if allowed to dry. 



The principal types of washers in use are the following: (a) dump 

 hopper; (b) worm (helicoid) ; (<?) spray apron; (d) rotary; (e) 

 paddle agitator; (/) air blast (geyser); (g) cascade. 



(a) The dump hopper is now used by only a few small packers. 

 It has practically nothing to recommend it as a washer. 



(b) The old-style helicoid worm washers also are being replaced 

 rapidly by the more modern types. 



(c) In the plain apron washer the tomatoes are carried on an open- 

 work apron through an inclosed chamber in which are strong sprays 

 that strike the tomatoes at various angles. This type of washer does 

 satisfactory work provided the water pressure is high enough (some 

 advise 100 pounds or more per square inch), and the soil on which 

 the tomatoes are grown is not of a very sticky character. If a high 

 pressure is used the apron washer assists materially in eliminating 

 soft rot spots, although, of course, it should not be expected to do 

 the work which properly belongs to the sorters. The type of nozzle 

 used on these machines, however, offers opportunity for improve- 

 ment. A nonclogging, flat spray form is much needed. The common 

 spray form of nozzle usually employed does not deliver the force of 

 the water evenly. Since the water is delivered in a circular form the 

 tomatoes passing along the edges of the circles get the force of the 

 stream for a longer time than those going through nearer the center. 

 The orifice of emission of the water in this type is so narrow that it 

 clogs quickly unless the water supply is very free from solid particles 

 such as scale from the inside of the water pipes. Nozzles working 

 on the impact principle do not seem to be so subject to these objections. 



(d) The rotary washer consists of an inclined cylinder covered 

 with a wire screen of 1-inch mesh. It is very commonly used and 

 generally gives good results. Its advantages are that it rubs the 

 tomatoes against each other, thus loosening the dirt, and it does the 

 washing with a less expenditure of water than most of the other 

 washers that give satisfactory results. Furthermore, it will remove 

 some of the soft-rot tomatoes. The principal objection urged against 

 it is that the manner of its operation tends to crush some of the very 

 ripe tomatoes, which may be sound but so ripe as to be tender. 



(e) In the paddle-agitator washer the tomatoes are dumped into 

 a tank of water where they float and are agitated by slowly revolv- 

 ing paddles, which cause the tomatoes to rub against each other, thus 

 loosening the dirt. At the same time the tomatoes are worked along 

 toward the conveyor, which removes them from the tank. As they 



100635°— Bull. 56&—17 2 



