Part 1

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KETCHUP

METHODS OF MANUFACTURE

A. W. BITTING

MICROSCOPIC EXAMINATION

K. G. BITTING

LAFAYETTE, IND. MURPHEY-BIVINS CO. PRESS 1915

This brief presentation of some facts concerning the manufacture of ketchup and discussion of the methods for its examination is offered in appreciation for the many favors shown to us by manufacturers. The text has been kept as free from technical terms as the subject would permit, and the results of observations and experiments covered by direct statements instead of giving details and tables.

Nothing new is offered in the method of manufacture, but the doctrine of the use of sound fruit, sanitary methods, and sterilization is reiterated. The position taken upon the method of examination is not new but it is thought proper to present something concerning this phase of the work to the manufacturer.

KETCHUP

Ketchup is a spiced sauce used for its condimental effect in imparting flavor, or to give relish to other foods. It receives its distinctive name from the base used, as, tomato, grape, currant, mushroom, walnut, etc.

The terms ketchup, catchup, and catsup are used to designate any spiced sauce and seemingly without any reason for the one used other than personal preference. Though the derivation of the term has been attributed to different sources by the dictionaries, there seems to be more reason for the use of the term ketchup than for the others, both upon the ground of its prior and more general use, and from the history of its derivation. Murray[1] gives the derivation of ketchup from the Amoy dialect of the Chinese, the term being =koechiap= or =ke-tsiap=, meaning a brine of pickled fish or shell fish; and he states that the Malayan =kechap=, which has been claimed as the original source, may be from the Chinese, but that the word =kitjap=, as given by some dictionaries from the Japanese, is an impossible word for that language, and is possibly an error for Javanese. The term catchup given by some dictionaries appears to be based on the assumption that the first syllable ketch is a colloquial form of catch. Many manufacturers use the word catsup, a spelling for which there seems to be no etymological warrant. The earliest use of the term catsup, found by the writer, with any particular significance attached to it as distinct from the other two terms, is by Kitchiner, an English physician, in the Cook’s Oracle, in which directions are given for reducing “catchup” to half the quantity, the statement being that “it may then be called double cat-sup or dog-sup.” The first edition of the book appeared in 1817 in England.

Footnote 1:

Murray, J. A. H. New English Dictionary.

THE MANUFACTURE OF TOMATO KETCHUP

It is but natural that a product of this kind should vary greatly in flavor due to the selection and quantity of spices, salt, sugar, and vinegar used, and in consistency due to the degree of concentration and fineness with which the base has been comminuted. Most of the recipes for home-made ketchup call for rather liberal spicing and long cooking so that they have a fairly heavy body. These insure good keeping quality, but impart a dark color to the product.

The manufacture of ketchup upon a large commercial scale is of rather recent development and is confined almost wholly to the use of tomatoes as a base. There was little ketchup of the kind best known at present made prior to 1890, as most ketchup was made by what was known as the natural fermentation method, that is, allowing the tomato pulp to ferment spontaneously and using the solid portion for stock. This method was continued, though on a decreasing scale, until 1908, at which time it was practically prohibited. Beginning about 1890, ketchup was made from fresh pulp and barrel stock without fermentation, the fermentation being prevented by the use of a preservative. The method is still in use. The first extensive manufacture of non-preservative ketchup began about 1908, though a few firms had been making it prior to that time, the pioneer probably being E. C. Hazard, of Shrewsbury, New Jersey.

From the amount of space given to the subject of ketchup in the canning and food journals, one might conclude that it is a difficult product to make, or that it is one of very great importance. It is in reality very easy to produce, but has assumed a prominence among food subjects which it does not deserve, due to the fact that some manufacturers have not yet learned the necessity for using care, or persist in using material of questionable quality.

Ketchup is made in the home with very simple apparatus; a colander or sieve for breaking and straining the pulp, and a copper, porcelain, or earthen kettle for cooking, being all that is necessary. The cooking of the tomatoes with the spices, sugar, vinegar, etc., is generally done slowly, until a heavy body is obtained, which results in a dark color, but insures sterility of the product when it goes into the container, and also contributes to keeping quality after it is opened. In the factory many refinements are necessary to make a commercial article which will attract the eye as well as satisfy the sense of taste. The usual dark colored, rough, home-made article will not command a sale over a grocer’s counter alongside of that made in a modern commercial kitchen. Here, sorting tables, washing machine, scalder, cyclone for pulping, steam-jacketed kettle, tanks with coils, or vacuum pan for cooking, finishing machine, bottle washing, and filling machine, are all necessary. The pipes carrying the pulp from one machine or vat to another must be enameled, bronze, tin-lined, or silver-plated to prevent the fruit juice from coming in contact with iron or anything which will cause discoloration. The work is done speedily, and the cooking done in the shortest possible time in order to secure the brightest color and smoothest consistency.

The stock should be whole, sound, ripe tomatoes, preferably grown near the factory so that they may be delivered promptly after picking and with the minimum injury. They should be picked when in prime vine-ripened condition. Fruit picked when just turning and allowed to stand one or two days to color will not have the same rich flavor as when vine-ripened, but will stand rougher handling. Green fruit gives a weak color, and over-ripe fruit is prone to become injured and spoil in handling. The tomato should be through the process of manufacture within twenty-four hours from the time that it is taken from the vine. Repeated experiments have shown that rapid handling of fruits and vegetables gives the best results for canning, and the tomato is no exception to the rule when used for ketchup.

The variety of tomato used is of importance. The tomato will vary in solids from less than 5.5 per cent to nearly 8.75 per cent; in soluble solids from less than 3.5 to nearly 6.5 per cent; in sugar from about 2.25 per cent to 4.25 per cent; and in acidity from .3 per cent to .6 per cent. The colors will vary from an almost creamy white to a very deep red with variations in yellow and purple. The only way to get uniformity in a product is to select one good variety and discard others. The preference is for a clear red smooth tomato of medium size, firm, and of fair acidity. While color may be only “skin deep” as far as being red, yellow, or purple is concerned, experience has shown that a clear red variety gives a better and more lasting color than yellow or purple. A medium sized smooth tomato is preferred because of less adherence of dirt, fewer cracks, and generally more even ripening to the stem. A fairly acid tomato imparts more flavor and needs less vinegar in the finished product. The fleshy portion of the tomato gives the body, but the pulp about the seeds furnishes the characteristic flavor.

The collecting of tomatoes in the field should be done at short intervals so that the fruit may be taken when in prime condition. Where picking is done at too wide intervals, there is a tendency to take fruit that is only colored and not really ripe, and for some to be left and become over-ripe. In both cases the manufacturer is the one to suffer, by increasing the expense of sorting, holding the green if he is to make a high grade product, and by waste from cracking and mashing of the over-ripe. The stems should be left in the field, as they increase the weight and may injure the product to a certain extent.

The handling should be in shallow crates. These should have strong cleats across the ends so that one may be placed above the other without touching the fruit, and if of considerable length, should have a partition. The cleats permit space for ventilation in case they must be stacked for a few hours or more. The depth should be such as not to permit more than three or four layers of fruit. The deep box and the conical basket are not well suited as carriers and should not be used unless delivery can be made by wagon direct from the field and within a few hours after gathering. It is the rule to see cars and barges loaded with baskets arrive at the factory with more or less of the fruit in bad condition. When one basket is set on the edges of two or three others in stacking, there is always cutting of a few of the top fruit, the movement in riding causes others to gradually settle and pack into the cone shape of the bottom, so that if they be held for a day or more, there will be loss of juice, consequent growth of mold, and contamination of the sound fruit from the infected. The actual loss from this form of handling has not been determined, but is undoubtedly much larger than is generally supposed. It is the belief of the writer that the loss is not far from 10 per cent. It is certainly much greater than the difference in the cost of freight and handling of the box over the basket. All baskets and boxes become more or less infected with mold during the season and this spreads to the fruit, the contamination increasing the longer the fruit is held, the tighter it becomes wedged together, or the greater the cracking. The shallow crate affords the better protection.

When tomatoes arrive at the factory, they should be purchased by weight for =sound= fruit. Buying by the box or basket is antiquated and not satisfactory to either buyer or seller. Under the recent Federal net weight law, purchase by basket or crate must show on each container the exact weight or measure if there be interstate shipment, and the same is true for some of the states. It should not be necessary to give more than a general inspection at the factory. A contract for ripe fruit at ten dollars per ton, which, when delivered, requires sorting, and the holding of unripe and the discarding of defective fruit, is equivalent to ten dollars, plus all the additional cost in labor and the loss in making it fit for use.

If it be necessary to hold the tomatoes for some time at the factory before manufacture, the crates should be stacked in tiers with a foot or more of space between each tier for the circulation of air. Stacking the tomatoes in solid blocks affords the ideal condition for the increase of molds. There can be no doubt that large quantities of fruit have been lost each year from neglect of this simple precaution. Recently a method of holding in water has been originated by Mr. E. W. Grosvenor, at Paoli, Indiana, and consists in using large tanks capable of receiving 500 or more bushels in which tomatoes are submerged in cold water as soon as received, and then held until they can be used. The device is based upon the theory that the tomato skin is practically impervious to water, also that the molds require air for their development and by submergence in water their activity would be lessened.

These tanks are made with false bottoms to receive the sand and dirt, are provided with jets to supply fresh water and to cause the tomatoes to automatically feed upon the conveyor. The first impression is that the tomatoes are soaking in rather dirty water, but tests show that they absorb very little, if any, water, and examination at every stage shows them to be washed cleaner than by the usual method. The work has not been carried far enough to be conclusive, nor to indicate its limitations.

Experiments made to duplicate the factory conditions, comparing air and water storage for short periods, were decidedly favorable to the latter. Much less change occurred in water storage for twenty-four to forty-eight hours than in the air, and there was the further advantage that the tomatoes were washed freer from dirt, sand, and mold, and that rot was cut out better under the water sprays. Some lots of tomatoes were held as long as eighty hours, but this is not to be recommended. When rotting does occur under water, it is of a different character from that in the open and is far more offensive.

If tomatoes be accepted at the factory in a mixed condition, that is, greenish, ripe, and over-ripe, they should be passed first over a sorting belt and preferably one which will turn all sides of the fruit to the inspectors. The green fruit should be held out in separate crates to ripen, and the unfit fruit be discarded. If green fruit be not accepted, the inspection can be done better after washing. In any event the fruit must pass slowly on the table and in single layers. No inspection can be made adequate if the tomatoes pile on the belt two or three layers deep, or pass at such a rate that the eyes tire and all look alike. This is a place where more belts moving slowly, and fewer persons working on each belt, will give the better results. Hand sorting is essential and far more important than in tomato canning. In the latter the defective parts are cut away, but no machine has yet been devised to make the separation complete in making pulp or ketchup.

One other point in inspection is the removal of the stems, which should be the duty of the pickers, but which is often neglected. If the ketchup is to have the brightest, cleanest color, the removal of the stem is advantageous and, furthermore, if the tomatoes are raised on sandy ground, there may be enough sand held around the stem to make appreciable grit. Some manufacturers leave the stem on to give flavor.

WASHING.

The washing is the most important mechanical operation in making pulp or ketchup in order to get a clean product. It is the weak spot in most factories, but fortunately is the one that can be most easily changed. The ideal washer is one that first receives the tomatoes in a tank, holding them for a sufficient length of time to soak and to loosen the dirt, and then submits all parts to a thorough spray under strong pressure. Most washers do not meet these requirements. In many cases the tomatoes are either not dropped into water, or go in and then out again so quickly that they are only made wet and bright, but not clean, then pass under a few cross-sprays, each of which does not deliver a stream more than an inch or so in width, the total spraying not being active over a space of more than six inches and only from above. Some machines do not actually spray the fruit more than one or two seconds. In some cases, it is not so much the fault of the machine as that of the owner in over-speeding and over-loading it. Most machines use a sufficient volume of water, but not under sufficient pressure, nor over a sufficient area. One of the best washers in use is a slight modification of the cylindrical washer used for removing the lye and peel from peaches. It consists of a cylinder about two feet in diameter and twelve feet long, made of a specially corrugated iron. The corrugations are sharper than the ordinary pressed metal used for building and siding, and in addition they are perforated at frequent intervals. This cylinder is mounted on a slight incline. The tomatoes are fed in at one end and the revolving motion causes their discharge at the other. The effect of the corrugation is to cause each tomato to turn over and over in its course and thus avoid all sliding. A spray pipe passed through the entire length and, when provided with the proper nozzle, insures a thorough washing, the tomatoes being under actual sprays from six to twenty times as long as in many machines that are now in use. The water pressure should not be less than sixty pounds per square inch and is better above one hundred pounds if fine perforations or nozzles be used. In nearly every case it is necessary to augment the natural pressure by an auxiliary pump. The principle of the strong pressure is seen in using a hose without a nozzle to wash a floor and one with a nozzle and strong pressure. In the former case it does not clean, while with the latter it does and with less water. The washer just described is too vigorous for tomatoes for canning, as the treatment is too rough. If the tomatoes are soft or badly cracked, it causes considerable loss, but not of material that should be used in ketchup. The strong sprays will also cut off adherent mold and soft rot. A thoroughly good washer will do about nine-tenths of the work for the inspectors. During the past season some modifications have been made of this washer in the east. The machine has been enlarged, but better results would be obtained by using a greater number of small ones. Again, some washing machines have been ineffective, not on account of any defect, but because of over-speeding.

The vigor with which the washing is done is always apparent in the finished product. The poor washing usually given to tomatoes for canning, accounts in a measure for the relatively large numbers of organisms found in ketchup made from trimmings.

PULPING.

After washing, the tomatoes may be reduced to a pulp in one of three ways: by running the raw tomatoes directly through a grinder and into the cyclone; by passing the tomatoes through a scalder and into the cyclone; and by turning the tomatoes into jacketed-kettles or tanks and cooking them until soft before running through the cyclone. There is a difference in the product obtained by these methods. The first one gives a somewhat larger yield, as the hard parts are cut and torn so that more will be squeezed through the sieve. The color is generally stronger and inclined to the purple side rather than the yellow. The color, however, does not hold so well when exposed to light. The pulp inclines to froth and there is a marked separation of red pigment on the top. A raw pulp will begin to separate into a clear layer below and solids at the top in about fifteen to twenty minutes after standing in a tank. This is due to the air incorporated in the solids and possibly to difference in specific gravity, and not to fermentation, as frequently alleged. Changes will take place more rapidly in such pulp than in that made from scalded fruit.

There is not a great deal of difference between the second and third methods, the object in both cases being the same. If a long scalder be used, the skins will be loosened and the tissue softened so that it will be easily separated from the green parts, hard cores, or black rot. There will be no acquisition of color from the stems to discolor the ketchup. The loss is a little heavier in scalder heating than where the fruit is cooked in the tanks, but there is the compensation that there is less carrying of hard or objectionable material. A scalder to be effective should be much longer than that used in canning, or a greater volume of steam should be used. The tomatoes should be heated to about 180 deg. F. There is little choice in the two methods, but the preference is with the scalder, both being preferred to the raw ground fruit. A pulp made in this way separates slowly and there will be no material increase in organisms for a rather long time (three or four hours). There is less separation of pigment on cooking and there is a clean look to the tissue under the microscope.

In making pulp it is important that the paddles in the cyclone be held back from the screen and the juice driven through by centrifugal force rather than by hard grinding. When kept well back, the green butts, cores, and tissues which have been hardened by brown mold are carried over the end so that there will be fewer black specks in the finished pulp and it will have a better appearance under the microscope.

The pulp should be conveyed immediately from the cyclone to the cooking kettle, and the next operation begun at once. A storage tank is unnecessary when there is large cooking capacity, and in most cases it is a source of trouble rather than a help. A sample should be taken as soon as the batch is drawn, and the specific gravity determined so that the proper quantity may be used to give a finished product of uniform consistency. Assuming that 500 gallons of pulp will give a normal finished batch, if the tomatoes are watery, it may require 550 gallons or more to give the same result when concentrated. This is easily calculated from the specific gravity so that reasonably uniform results may be obtained. Samples should also be tested for acidity once or twice each day so that the addition of vinegar can be governed accordingly. The concentration of pulp will vary from 40 to 60 per cent depending upon its condition and the weight of body desired.

COOKING.

The cooking is done in copper-jacketed kettles, in glass-lined metal, or in wooden tanks, the tanks being heated with coils. The glass-lined tank has the advantage of very little metal coming in contact with the pulp and can be kept cleaner than wood. A question has been raised regarding the suitability of copper for a cooking utensil, though no positive objection has been made. The vacuum pan is coming into use for concentrating pulp, but has been little used in making the finished ketchup. The jacketed-kettle is used by most manufacturers, though the tank and coil is being adopted by those who wish to make large batches, as it is the more economical. Agitators are no longer used, as by proper handling of the steam and automatic traps, little burning occurs on either kettles or coils. The efficiency of the open tank or kettle is increased by providing a strong exhaust or suction for the air at the back and just above the top of the kettle. A swiftly moving current of air across the top of the kettle will carry off the steam and shorten the time of heating from ten to twenty per cent.

A pulp may be reduced in a vacuum pan in about one-fourth the time necessary in the open kettle and with a marked conservation of color and flavor. The vacuum pan may be used for quick reduction and the finish be made in open kettles in order to apply the heat long enough to spice and to sterilize. There are possibilities along these lines which have not been developed.

The time of cooking a batch of ketchup will depend upon the equipment and the consistency of the finished product. With a good kettle or coil and ample steam-supply a batch should be completed in from thirty-five to forty-five minutes. This gives sufficient time to get the most desirable flavor from the spices and is not so long as to result in discoloration.

SEASONING.