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.