CHAPTER V

CONVEYING THE CONDENSED, STRAINED, OR CRUSHED TOMATOES TO THE FINISHING MACHINE AND FINISHING SAME

Conveying to Finisher

The fewer pipes and receiving tanks the condensed pulp passes through before being filled in the cans, the better. All of this conveying and finishing equipment offers possibilities of contamination, and allows the cooked pulp to cool to some extent before it is filled. Eliminate as much equipment as possible between the cooking kettle and the filler, and have the pulp enter the cans at at least 170 degrees F., and if possible, at 180 degrees or above. A receiving tank between the cooking kettles and the filler should be dispensed with if possible, and the finishing machine draw the cooked pulp direct from the kettle by means of a short line of enamel lined pipe.

Receiving Tanks

Unfortunately the arrangement of many plants is such that it is almost necessary to use a receiving tank; at least in such cases it would be a disadvantage not to have one. Where a tank must be used here it should be in such a position that it is easily accessible, so that it will not be necessary for a man to be an acrobat to get into it, inspect it, and see that it is kept clean, and that an inch of pulp is not allowed to lie in it and get cold while waiting for another batch to come down.

The best kind of a tank for this purpose is an enamel or glass-lined tank with a rounded, tapering bottom so that it will almost drain itself completely, and what little adheres to the sides can be scraped down in a few seconds if it is necessary to wait five or ten minutes for a fresh, hot batch to come down. Even if it isn’t scraped at all it will probably not cause any trouble in a tank like this. Wooden tanks will do, of course, but it would pay a packer who must use a tank here to throw out his wooden one and put in a tank such as is recommended above. It is hard to construct a wooden tank so that it will drain well; in fact, nine out of ten scarcely drain themselves at all; they are never kept as clean as they should be, and wet wood seems to be a favorite spot for molds to grow, so that frequent scrubbing is necessary if it is kept sanitary. It is most important to inspect the receiving tank carefully before it is first used in the morning, as they sometimes mold slightly over night, or dirt falls into them from overhead. A steam hose should be kept close to a wooden tank to sterilize it at night after it is scrubbed out.

Finishing

Whether or not a receiving tank is used, the finishing machine should be as close to the cooking kettles as possible, and should receive constant attention from a careful operator who can comprehend to some degree the importance of keeping it clean. If the filling department gets ahead of the cooking department and is obliged to wait fifteen minutes or a half hour for a fresh batch of pulp to come down, the man who tends to the finisher should take it apart at once, wash it off, steam it off thoroughly with the steam hose, and put it together again so that it will be clean and practically sterile when it receives the next batch. Otherwise the screen and the brushes will be clogged up with cold pulp when the fresh batch comes down, which is a bad condition, especially if the pulp is not to be sterilized after it is filled, which is usually the case with 5–gal. pulp. Even though the finisher is operated continuously through the day, it should be taken apart and cleaned at least twice during the morning and twice during the afternoon.

The finishing machine should be operated slowly, so that the pumice will come out dry. The small receiving box under the finisher should drain completely so that it does not have a foot of cold pulp lying in it when the finisher is idle.

Screen Metal for Finisher

The best kind of screen for the finisher is made of monel metal. The brass screen is more common; however, the same thing can be had in monel metal, and it does not offer the opportunity for metallic contamination that the brass screen does. The monel metal screens wear very well and have proven themselves to be satisfactory in every respect. Aluminum should not be used, as it is eaten up by the tomato acid and will not last long.

Effect of Finishing on Mold Count

The opinion has often been expressed that the brushing of the pulp through the fine meshes of the screen breaks up the small clumps of mold and scatters them in small threads throughout the mass, thus increasing the mold count, since this count is not based on the total quantity of mold present, but upon the number of microscopic fields containing molds. Thus, by scattering the mold, instead of allowing it to be retained in comparatively large clumps, the number of microscopic fields containing mold threads would be increased.

Although one might reasonably expect this to take place, experiments have proven that it does not take place. Several years ago, in order to determine this point, I analyzed thirty batches of catsup just before entering the finisher and again just after coming through the finisher. In every case the percentage of microscopic fields containing molds after finishing was practically the same as before finishing. A cone-shaped finisher with three revolving brushes and fine mesh screen was used for this test.

Finishing Before Cooking

Although the finishing machine, if properly tended to, is probably responsible for very little of the spoilage in pulp, it has been suggested to use the finisher before the pulp is condensed. Then the pulp can be drawn direct from the kettle to the cans, and the chance of contamination and cooling in the finisher can be eliminated. This idea is well worth experimenting with, as the pulp could be filled at almost the boiling point. I have not tried out this idea, but offer it here as a possibility which has advantages which are well worth looking into. Packers who are having spoilage trouble which they cannot attribute to other causes would do well to experiment with it. As to whether both the pulp machine and finisher would have to be used before the cooking, or whether the finisher alone would do, providing the tomatoes were previously crushed, or cooked in a “breaking tank,” would have to be determined by experiment. The method may be in use now by some packers; however, I have not heard of it being used.