Ketchup: Methods of manufacture

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KETCHUP

METHODS OF MANUFACTURE

A. W. BITTING

T-i I L/

MICROSCOPIC EXAMINATION
K. G. BITTING

This brief presentation of some facts
concerning the manufacture of ketchup
and discussion of the methods for its ex-
amination is offered in appreciation for
the many favors shown to us by manu-
facturers. 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 state-
ments 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 condi-
mental 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 with-
out any reason for the one used other than personal
preference. Though the derivation of the term has
been attributed to different sources by the diction-
aries, 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* 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 dic-
tionaries 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, foand
by the writer, with any particular significance at-
tached 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.

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

KETCHUP

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 con-
centration 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 com-
mercial 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 Shrews^
bury, 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

METHOD OF MANUFACTURE 5

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 neces-
sary. 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 com-
mercial 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 con-
sistency.

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

6 KETCHUP

prone to become injured and spoil in handling. The
tomato should be through the process of manufac-
ture within twenty-four hours from the time that
it is taken from the vine. Repeated experiments
have shown that rapid handling of fruits and vege-
tables 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 con-
cerned, experience has shown that a clear red va-
riety 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

METHOD OF MANUFACTURE 7

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 OP
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, conse-
quent 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 sup-
posed. 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.

8 KETCHUP

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 satisfac-
tory 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 dol-
lars per ton, which, when delivered, requires sort-
ing, 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 to-
matoes are submerged in cold water as soon as re-
ceived, 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 sub-
mergence in water their activity would be lessened.

These tanks are made with false bottoms to re-
ceive 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

METHOD OF MANUFACTURE 9

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 con-
ditions, 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 prefer-
ably 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 in-
spection 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,

10 KETCHUP

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 to-
matoes are raised on sandy ground, there may be
enough sand held around the stem to make appre-
ciable 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 fac-
tories, 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 cylin-
drical 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 per-

METHOD OF MANUFACTURE 11

forated 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 de-
scribed 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 ac-
count 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 num-
bers of organisms found in ketchup made from
trimmings.

12 KETCHUP

PUI/PING.

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 incor-
porated in the solids and possibly to difference in
specific gravity, and not to fermentation, as fre-
quently alleged. Changes will take place more rap-
idly 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

METHOD OF MANUFACTURE 13

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 miscroscope.

The pulp should be conveyed immediately from
the cyclone to the cooking kettle, and the next
operation begun at once. A storage tank is unneces-
sary 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 con-
centration of pulp will vary from 40 to 60 per cent
depending upon its condition and the weight of body
desired.

14 KETCHUP

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 com-
ing 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 dis-
coloration.

METHOD OF MANUFACTURE 15

SEASONING.

The selection of the spices depends entirely upon
the flavor desired. Cinnamon, cassia, cloves, allspice,
mace, pepper, paprika, cayenne pepper, mustard,
ginger, coriander, bay leaves, caraway and celery
seed, are all to be found in the various formulae.
Some manufacturers spice lightly in order to retain
the maximum of the base flavor, while others go to
the opposite extreme on the misguided assumption
that they will act as preservatives. The quantity
used should be determined by the flavor desired
and upon no other consideration. The spices may
be used whole, ground, or in some cases as acetic acid
or oil extracts. The whole spices are preferred by
nearly all the manufacturers of high grade goods.
They are more expensive, but give a different flavor
from the extracts. The spices are weighed for each
batch and are tied in a bag or placed in a wire
basket and suspended in the kettle while cooking.
Some use very large quantities and cook from only
ten to twelve minutes in order to get a distinctive
flavor. This is very expensive, as only a small
quantity of the flavoring matter is extracted in such
a short time. One of the serious objections to the
use of the whole spices is that they may darken
the ketchup and also cause some discoloration in the
neck of the bottle. For that reason, black pepper
and allspice in particular are being discarded, and
oil of cloves is being used in part for the whole
berries. The grade of the spice will also have an
effect, the cheap stock being unsuitable for a bright
clean product. Small quantities of ground cayenne
pepper are used as a substitute for the black pepper.

Acetic acid extracts of some of the spices are
being used to a certain extent, but they have a
peculiar harsh flavor that makes them undesirable.
The oil extracts can be used to only a very limited
extent, as they impart a flavor suggestive of the
drug store.

16 KETCHUP

One method of making a nearly complete extrac-
tion of the spices is to place them in their proper
proportion in vinegar a few weeks before the
ketchup season begins and then add the spiced
vinegar in the proper proportion to each batch. The
result is different from that obtained by cooking,
and the method is not recommended for first grade
goods.

The waste of spices in the usual process of
manufacture is indicated by some work done by
Mr. H. E. Bishop of the laboratory of the Indiana
State Board of Health. He found that in making
ketchup, when the boiling was kept up for thirty
minutes, that only 27.8 per cent of the oil of cassia,
11.5 of the oil of cloves, and 33.3 per cent of the oil
of allspice were extracted. (Unpublished report.)

Paprica rosen, Hungarian, or sweet paprika, is
used for coloring purposes, though it parades as a
spice. This is a mild variety of Capsicum annuum,
one of the species of the genus Capsicum, from
which cayenne pepper is made. The variety offered
to manufacturers has a more intense red color and
much less pungency than the ordinary paprika. This
paprika can be obtained as the bright fruit, ground
dry, or in oil. In the latter, it is said, that part of
the capsicin is removed, also that the oil sets the
color in inferior material. The oil is of a reddish-
yellow color and the large number of globules and
irregular masses serve to distinguish it from cap-
enne pepper. It fulfills the claims of the importers
— "coloring the ketchup, not adding materially to
the pungency, and coming inside the laws in being
one of the regular ingredients." It requires just
about sixteen times as much as would be required
of ordinary paprika to get the same flavor. Con-
sidering the cost, in the relative proportion re-
quired, there can be little doubt of its real purpose.
It will conceal inferiority to ordinary observation
in that it gives a red color where otherwise a

METHOD OF MANUFACTURE 17

muddy color might be present. The color does not
have durability, and it is easily recognized under
the microscope.

Onions and garlic are added in varying quantities
and may or may not be kept in the batch through-
out the whole cooking period. Considerable differ-
ence in flavor is apparent with the length of time
of the cooking. Chili peppers are also used in hot
ketchup or cocktails.

Vinegar is added to nearly all ketchup. For-
merly the acidity was obtained from the fermenta-
tion of the tomatoes and the resultant acid was
probably mostly lactic. The flavor was different
and not so agreeable. A good cider, grain, or malt
vinegar may be used. Most manufacturers prefer
to use grain vinegar of ten per cent acidity, as the
volume required is less and interferes less with
concentration. For real flavor, however, this may
not be the best. Lately, glacial acetic acid has
been substituted for vinegar, a practice which can
not be approved and which ought to be abandoned.
Citric acid is also added by some. Vinegar is
usually added near the finish of the batch, as other-
wise it attacks the kettle to some extent and a part
is driven off in boiling. Experiments made by add-
ing vinegar to pulp and evaporating to fifty per
cent of its weight in twenty and forty minutes,
respectively, show that in the former case the
added acidity was decreased in almost the same
proportion as the total evaporation, but in the latter
case the acid was not driven off quite so rapidly as
the moisture. This does not correspond with views
held by chefs, as most of them seem to believe that
practically all the vinegar is driven off. In order
to obtain the sterilizing effect of boiling in an acid
medium, it is advisable to make this addition at
least five to ten minutes before the end of the
cooking period. In home-made ketchup, vinegar is
usually added near, or at, the start, and aids in

18 KETCHUP

sterilizing the product, as boiling alone may not,
whereas, boiling in the presence of an acid will,
sterilize.

Oil is not an essential to ketchup, and while a
small quantity is often used to prevent foaming, its
use in large quantities is undesirable.

Sugar is added to give the desired flavor. The
higher the acidity, whether natural, or acquired by
adding vinegar, the greater the quantity of sugar
needed. In the high grades of ketchup, granulated
sugar only is used, but in the cheaper grades, soft
sugar or glucose, may be used, though the latter
must be declared on the label. The sugar is usually
added when the cooking is about one-half completed.
There is an advantage in heating both the sugar
and vinegar in a separate kettle and adding them
while hot, as it will prevent a check to the cooking
and lessen the sticking to the coils or kettle.

Salt is used in small quantity and is added near
the close of the cooking process.

The use of flour or starch in any quantity for
the purpose of making the body thick or heavy is
properly regarded as an adulteration. This is also
true of pulp from a foreign source, like pumpkin
or apples.

The density of the ketchup is left usually to the
judgment of the chef, who depends upon the ap-
pearance as it pours from the ladle. A quick test
can be made by weighing, as done for pulp, but in
this case each manufacturer must determine his own
standard. A ketchup having specific gravity of 1.090
is apt to be thin ; a satisfactory consistency ia
usually about 1.120 to 1.140.

As soon as the cooking is completed, the ketchup
is run through a finishing machine to remove all
hard particles of tomato, bits of spice, etc., and to
give smoothness to the product by breaking it up
into very small particles. There are two types of
finishers, the shaking sieves and the rubbing ma-

METHOD OF MANUFACTURE 19

chines. The former is suitable for thin ketchup.
The resultant product gives the best possible ap-
pearance under the microscope, the tissue showing
whole cells, little tearing, and the minimum amount
of debris and mold filaments. The objections to the
sieve are that the capacity is small and the waste
is comparatively large. The rubbing finisher needs
to be very carefully adjusted, otherwise it forces
practically everything through in a very finely
comminuted state. The cells of the tissues are torn
to shreds, their contents discharged, molds are
broken into hundreds of fragments, and a ketchup
may be made to have the appearance of being made
from poor material. The finishers have large ca-
pacity and will work on either light or heavy
goods, but like the cyclone, must be handled with
judgment, not attempting to force the last ounce
through the sieve.

BOTTLING.

Only new bottles should be used and these should
be thoroughly rinsed before using and preferably
with hot water. Since new bottles have no tightly
adherent particles on the inside, the use of clear
water is sufficient, dependence being placed upon
the after process to insure sterilization.

The bottling should be done at as high tempera-
ture as is practicable, about 165 to 170 degrees F.
If the temperature is higher than this, the possi-
bility of burns in handling is increased, and too
much space is left in the neck of the bottle after
corking, due to shrinkage of the ketchup on cooling,
and if much lower, the expansion in processing
causes excessive loosening of caps or corks and
breakage. Furthermore, when low temperature is
used, it requires a very long time to heat the con-
tents of a bottle in pasteurizing. A ketchup is a
very poor conductor of heat and the heavier the
body, the longer the time that is required.

20 KETCHUP

The closure may be made with either corks or
seals, the recent improvements in the latter making
them much safer than they were a few years ago.

PROCESSING.

After the bottles are sealed, they should be given
a process to insure sterility, the time being about
fifty minutes for half-pints and an hour and fifteen
minutes for pints — or sufficient time to insure 190
degrees F. for twenty minutes at the center of the
bottle.

This step is omitted by many manufacturers,
dependence for sterilization being placed upon wash-
ing the bottle and subsequent heating for about
twenty minutes. The heating is accomplished by
conveying the bottles through a chamber containing
numerous steam pipes at high temperature and dis-
charging them at the bottling machine. It is as-
sumed that sterilization of the ketchup has taken
place in process of manufacture, and the heat within
the bottle will care for any infection which may
possibly have taken place at a later time from the
cap or cork. The safety of this measure depends
upon using a fairly acid ketchup or one with a
heavy body. It is a risky procedure for mild or
thin ketchup. It is a common occurrence to have the
stock keep apparently while in the bottle, but spoil
shortly after opening. The spoilage after opening
is most often due to forms which have been present
since manufacture and only need the presence of
air to start growth, and are not due to infection
from the air. A ketchup will inhibit the growth
of organisms which gain entrance from without,
while those which are present but held in abeyance
through exclusion of air, will sometimes grow. The
writer has samples of ketchup put up in 1906
which apparently are sterile, but which will show
spoilage within a few days after opening, though
done under sterile conditions, and the spoilage be

METHOD OF MANUFACTURE 21

identical in kind with that observed soon after
manufacture. How long these organisms will re-
main alive is not known. In canning, no foods are
considered safe without processing, and the same
principle is a good one to follow with ketchup.

Processing may be accomplished in open tanks,
in retorts, in specially constructed pasteurizers, such
as used in the brewing industry, and in hot cham-
bers, the method is not material, though there may
be considerable difference in point of economy.

FACTORY ARRANGEMENTS.

The making of ketchup is simple and the factory
arrangement for doing the work should be as com-
pact as possible, so that after the pulp is once
heated, there is an advantage in having the various
steps follow in succession by gravity rather than
be conveyed by pumps, especially in small plants.
The piping should be as short and direct as possi-
ble. The machinery for filling bottles, corking, etc.,
leaves much to be desired; as separate units they
work fairly well, but there needs to be some method
devised for handling the bottles automatically from
the time they are placed on the washer until they
are labeled, ready for the box. At present the time
between turning the crate of tomatoes upon the
sorting belt until it is ready for the box is only
slightly over two hours. Further improvement will
not be so much in shortening the time as in elimi-
nating the hand labor.

The foregoing description applies to the making
of unfermented, non-preservative ketchup, made
from sound stock and delivered into the bottle.
Very little ketchup, comparatively speaking, is sold
to the consumer in any package other than the
bottle. It can be delivered into the bottle when
first made, at less expense for labor, with less fuel,
and with distinctly less waste than at any subse-

22 KETCHUP

quent time. It will have a better color and con-
sistency than if stored in bulk and bottled later.
It is, therefore, advisable to bottle as much as
possible at the time it is made. Ketchup may be
packed in bulk in jugs, tin cans, and in barrels, but
not satisfactorily; the jug is a poor package; the
enamel may be dissolved off the tin can and pin
holes form; and the barrel always gives a poor
color and off flavor. The best container for bulk
ketchup is the gallon glass bottle.

PTJL.P STOCK.

During the height of the season, it may not be
possible to convert all the tomatoes directly into
ketchup, in which event the surplus may be made
into pulp. The first part of the operation is identi-
cal with that already described. The concentration
is carried just far enough so that subsequently by
slow heating for spicing it will give the proper
consistency when made into ketchup. A standard
has not been fixed, but tentatively it has been pro-
posed that it be at about a specific gravity of 1.035.
The concentration may be carried further and water
added at the time of the final cooking, but when
this is done, the resultant product does not have the
same smooth consistency that is obtained by using
the thinner pulp. Heavy pulp is made for the
purpose of economizing in cans, but experience has
shown that economy does not always follow. The
higher the concentration, the higher the acid con-
tent, and this may attack the enamel and metal with
resulting bitter flavor and frequent pinholes. Some
manufacturers who prepare their own pulp carry
the concentration between 1.030 and 1.033. The
method of obtaining this density is to use flasks
graduated to hold 500 or 1000 grams of water at 200
degrees F., fill them with the hot pulp and weigh at
once. For each flask there should be a proper
counterpoise, and the balance be sensitive and weigh

METHOD OF MANUFACTURE 23

in grams. If the 1000-gram flask be used, the spe-
cific gravity will be the same as the weight of the
pulp. With a valve funnel the flask may be filled
level full and the weight taken in less than thirty
seconds. For cold pulp, a similar flask is used, but
graduated at 60 degrees F. and after filling, the
flask is set in a sling and whirled a few times to
free it from bubbles, filled again to the level, and
then weighed. For pulp of a specific gravity of less
than 1.037, this gives fairly concordant results, but
the errors increase rapidly the higher the concentra-
tion. The same methods may be employed on
ketchup. Recently, W. D. Bigelow has improved the
apparatus by using a copper flask and adding a
handle by which the flask may be submerged in
the kettle to take the sample and thus prevents the
entrance of air. The use of flasks of any size is
described in Bulletin No. 3, National Canners' Asso-
ciation.

The use of the specific gravity method only
partly solves the question of standardization. Two
pulps each of 1.035 may vary considerably in what
the chef terms body and there is no method of
accurately measuring this factor or expressing it.
Pulp made by draining will be lighter in weight
with the same body, and that from skins and cores
will be rough or have the appearance of separating
into small flakes or lumps. The specific gravity
bears a close relation to the soluble solids, and as
these do not have a constant ratio to the fiber in
whole fruit, and as the ratio is further disturbed by
drainage and in the use of trimmings, it is obvious
that the method will not give an exact standard.

Pulp should be filled into gallon or five gallon cans
as hot as possible and sealed at once. The practice
followed by some manufacturers is to steam the cans
first, then depend upon the heat in the pulp to
sterilize. The cans are allowed to stand hot for
forty minutes, then cooled. The other practice is

24 KETCHUP

to give the hot cans a process of about twenty
minutes for gallons, forty minutes for five gallons,
and then to cool. Cooling is essential to retain
color and flavor, as prolonged heat causes "stack
burning," producing a brownish color and a bitter
taste. The highest grade pulp can not be held in
barrels for the reason that the heat is retained too
long. Stack burning will take place in glass if
the packages are not allowed to cool well in the air
before being stored, though the changes are not so
marked as in the tin.

PUL.P FROM TRIMMINGS.

The losses in stock from canning tomatoes
amounts to about forty per cent. This is due to
the unbusiness-like attempt to can all kinds — very
large, very small, and wrinkled, which can not be
peeled with economy — to wasteful methods of peel-
ing, and to excessive draining of fruit from handling
in too thick layers. In this waste there is much
that has good food value and which might be
worked up into pulp or ketchup stock if properly
done. In order to do this, the tomatoes should be
sorted so that only those which are in perfect condi-
tion for canning will go to the peelers. These
should be medium sized, firm, evenly ripened all
over, and free from wrinkles. Such tomatoes can
be peeled at the minimum of expense and loss. The
sound tomatoes which are small, excessively large,
wrinkled, or with green butts, can go in with whole
tomato stock. The loss in peeling will then be
small and can advantageously be discarded. If it
be decided to use trimmings from the peeling tables,
provision must be made for extra washing, as the
ordinary washer removes little more than the coarse
dirt and particles, is not sufficient for unusual con-
ditions or to remove tightly-adhering material, and,
furthermore, rot must be eliminated before the to-
matoes go to the peelers. The writer has never

METHOD 'OF MANUFACTURE 25

seen a group of one hundred, or any number, of
peelers who will stop to trim and separate rot from
peels and cores. Trimming can be done better by a
few when sorting the tomatoes than at any subse-
quent step. If clean skins and cores can be had
from the peeling table, they can be converted into
pulp and sold if labeled properly, "from trimmings."
Whether such waste is suitable for a good product
depends upon how it is handled. For the most part,
it has not been handled as well as it should be.

The finished pulp made from skins and cores is
not the same as that from whole stock. It contains
more fiber, remains more or less lumpy, and lacks
the smooth body of whole pulp. The color is not so
good, and the flavor is likely to be somewhat dif-
ferent. The flavor of the seed cells and that of the
fleshy portion of the tomato are different. Pulp made
from each part separately shows marked difference,
that from the seed cells being poor in color, but
with the more characteristic fruit flavor. Testa
show that neither part has any true jellying powers,
but that the part from the seed cells gives the
quality of smoothness, the holding together of the
particles of solids. Neither gives a first class pulp
alone.

COI.OB.

Home-made ketchup generally has a rather dark
reddish or brownish color, due to prolonged heating,
made necessary under kitchen conditions. At one
time this was thought desirable and some of the
older recipes call for the use of caramel in order
to imitate this color. Most manufacturers now aim
to secure a clean, clear color, preferably bright red.
This may be obtained when good fruit is used and
handled quickly ; a muddy brownish or yellowish
color is looked upon with suspicion as indicating
poor material or defective methods.

26 KETCHUP

The necessity for a clear red variety has already
been pointed out, for without proper stock, a su-
perior product of uniform quality can not be made.
The tomatoes must be well vine-ripened, as the
presence of green fruit and green butts has a de-
cidedly dulling effect. Colorimeter tests show that
the use of even small quantities of green material
have an immediate dulling effect. Promptness in
handling the fruit after the tissue is once exposed
to the air is also essential. The tomato, like some
other fruits, turns brownish when the surface is
cut or exposed. This does not occur as rapidly, nor
is it so marked as in apples or in pears, but it is
present. When the tomato is converted into pulp,
every particle is exposed to the air for a very short
time — long enough to make some slight change. The
change is most marked in pulp from raw stock and
least in that which has been well heated. It natur-
ally follows that ketchup made promptly from whole
stock will have the best color, that from canned
tomatoes next, then canned pulp, and lastly, that
from trimming stock. Pulp allowed to stand hot for
too long a time will have a brownish color like stack
burning. When barrel pulp was used, this waa
ascribed to the tannin extracted from the oak.

Pulp should not come in contact with iron at any
stage, as the union of the acid of the fruit with the
metal will cause discoloration. When such discolor-
ation does occur, it becomes uniform throughout the
mass, and not in the neck of the bottle as has some-
times been described.

Darkening in the neck of the bottle is frequently
due to the spices used, as has already been pointed
out. It can be redistributed throughout the whole
by placing the bottle in a shaker for a short time.

Darkening at the top may sometimes be due to
extraction of color from the corks. Soaking corks
in two per cent acetic acid, then in hot water before

METHOD OF MANUFACTURE 27

drying, and paraffining, will, assist in preventing
dicoloration on cheap grades.

Discoloration in the neck also results from the
small amount of air incorporated and from any
subsequent addition which may come in through the
cork or seal. Bottles which are full to the cork
may show' no darkening, those having a space of
an inch or more between the contents and cork may
show little discoloration, while those having more
space will show much more marked discoloration.
This holds for both pulp and ketchup and in this
case the discoloration begins on the surface and
works downward. The product made from some
fruit will discolor more than that made from fruit
grown in another section of the country.

A bright red color is secured in some brands of
ketchup by means of paprika, as indicated under
spicing.

A light colored ring in the bottom of a bottle is
generally due to organisms and debris, indicative of
the use of barrel or trimming-stock pulp, or it may
result from changes after the process of manufac
ture. It has been mistaken for sand.

KEEPING QUALITY.

Ketchup must not only keep while in the un-
opened bottle, but for a reasonable time after open-
Ing, if it is to be a commercial success. Every
canner understands that if he puts food in a her-
metically sealed package and sterilizes by heat, that
it will keep until opened. The same principle
applies to ketchup in the bottle, but there are some
packers who wish to be spared this expense and
trouble and prefer to use a substitute for heating.

The keeping quality after opening depends upon
the utilization of the same principles followed in
the household operation of making fruit butters,
ketchup, preserves, and pickles, that is, sufficient
concentration and the use of sugar and vinegar. A

28 KETCHUP

ketchup can be made essentially a pickle with an
excessive quantity of vinegar and it will keep; it
can be made a preserve with excess of sugar and
it will keep ; or, it can be made a distinctive sauce
well concentrated in which the vinegar and sugar
are used only in sufficient quantity to give proper
flavor, and it will keep, Apple juice or cider will
spoil quickly if allowed to stand in a warm place;
apple sauce will behave in like manner only a little
more slowly; but if the juice and sauces be boiled
together until they have acquired the consistency or
state known as apple butter, they will keep very
well. The acidity, sugars, and solids have been in-
creased by the concentration. In the making of
tomatu ketchup, the fruit does not have sufficient
acidity and sugar of itself to give preservative
property at the concentration desired for a sauce,
so these are augmented by the addition of vinegar
and sugar.

A great deal of stress has also been placed upon
the effect of the spices in acting as preservatives.
Experiments have demonstrated conclusively that
when these are used in the small quantities re-
quired for flavoring, that their effect is practically
nil. The active principles of the spices are effective
only when present in the proportion of 1 to 500 or
600 and in ketchup the proportion is only 1 to
several thousand. Likewise the quantity of salt is
too small to have effect.

The keeping qualities of a mild ketchup will de-
pend far more upon the sterilization than most
manufacturers realize. It is easy to make almost
any ketchup apparently keep while the bottle is un-
opened. The spoilage after opening is most often
observed to be due to mold which has been as-
sumed to come from infection from the air. As a
matter of fact, this is nearly always due to spores
which have been held in abeyance, due to lack of
air while in the bottle, and which begin growth as

METHOD OF MANUFACTURE 29

soon as conditions are favorable. Spores which fall
into the bottle from the air might be unable to
germinate upon such a medium, while those already
present would.

CHARACTERISTICS OF COMMERCIAL KETCHUP

While tomato ketchup is a complex and variable
product,, its general composition may be determined
with a fair degree of accuracy. Inspection will give
a good idea of color, consistency, smoothness of
body, fineness of finish, tendency to separate, pres-
ence of objectionable particles, and evidence of gross
fermentation. The odor and taste will give a clue to
the kind and quantity of spices used and to a
certain extent the character of the raw material.
Judging by odor and taste is not so well done as
judging by the eye by most persons. The education
of those two senses has been neglected and there-
fore fail to give all the information which might
be acquired in this way.

A chemical examination which will give the spe-
cific gravity, total and soluble solids, sugar, salt,
and total and volatile acidity, will be sufficient to
give a good idea of the stock used — tomato, salt,
sugar, and vinegar, but not the spices. A micro-
scopic examination will assist in determining the
condition of the material used and whether decom-
position has taken place before or after manufac-
ture. The facts obtained through these sources will
permit of classifying commercial ketchup with a fair
degree of accuracy.

There has been a very marked change in the
character of ketchup since the transition from the
preservative to non-preservative goods, not only
microscopically, but also in composition. Formerly,
there were very many brands of thin liquid ketchup,
showing little concentration of pulp, very low in
sugar, and having only small quantities of vinegar;
the standard was bulk rather than quality. The

30 KETCHUP

microscopic examination also showed that the prod-
uct had frequently undergone change before and
after preparation. Recent examinations show that
there has been a very marked improvement; that
the body is decidedly heavier, more sugar and vine-
gar are used, the tissue is cleaner, and there are
fewer organisms present, also that the difference in
composition in preservative and non-preservative
ketchup is small, whereas, formerly it was marked.

The variations found in ketchup of rather recent
examination show in the non-preservative kind the
specific gravity varied between 1.091 and 1.177; the
solids between 19 and 37 per cent; the salt between
2 and 4 per cent; sugar between 12 and 29 per cent,
and volatile acids between .54 and 1.24 per cent. In
the preservative kind, the specific gravity ranged
from 1.032 to 1.120; the solids from 9.23 to 28 per
cent ; salt, 1.48 to 3.4 per cent ; sugar, 4.95 to 16.9 per
cent ; and volatile acidity, .16 to .64 per cent. As a class
they averaged lower in concentration of tomato and
in sugar and vinegar, though if proper sterilization
had been used, some of them would have kept with-
out difficulty. In experimental work it was found
that a ketchup concentrated so that when finished
it showed an added sugar content of 15 per cent
or more, a total acidity of 1.2 per cent, and a spe-
cific gravity of 1.120 or more, that it would keep.
To obtain a total acidity of 1.2 per cent means the
addition of about .4 to .6 per cent acidity in the
vinegar used. However, there are brands of ketchup
on the market which keep well after being opened
and which have a total acidity of less than 1.0
per cent.

The manufacturer can use the following as a
starting point for non-preservative ketchup; pulp,
100 gallons; sugar, 60 pounds; salt, 8 pounds;
vinegar, 100 grain, 2 gallons ; spice to flavor ; and
concentrate to 50 to 55 gallons.

MICROSCOPIC EXAMINATION 31

MICROSCOPIC EXAMINATION

A discussion of the microscopic appearance of
ketchup in terms which can be readily understood
by manufacturers is not an easy task, as it neces-
sarily involves technical knowledge. The subject
has become one of importance, owing to the attitude
of many food officials in enforcing a microscopic
standard for this product, and on the part of many
brokers in requiring a guarantee to comply with
this standard in making purchases. Many manu-
facturers have either assumed or found it necessary
to have their finished products examined. Some
employ "experts" to make the examinations in their
own plants, while the majority send their samples
to commercial laboratories. The total tax upon the
industry for such work amounts to thousands of
dollars annually. The result of the work as a
whole has been beneficial, as any effort is which
attracts attention to details. It has likewise been
the means of causing much unpleasantness and not
infrequently loss, because of lack of understanding
on the part of both manufacturer and examiner as
to the cause of certain findings. The manufacturers
have proceeded in the usual way without sufficient
knowledge of what the resultant product will be
unless there is careful supervision of material and
methods, while too frequently the examiner is
neither experienced in technique of the examination
nor in the effects of the different steps in manufac-
ture upon the product. Furthermore, much distrust
in microscopic finding is evinced when a half dozen
or more samples from the same batch, sent to as
many persons, result in as many different reports.
It naturally causes a lack of confidence in both
paid examiners and in food officials, though those
who make these examinations may be absolutely

32 KETCHUP

honest in their findings. In order to clarify some of
the points, it has become necessary to go into
detail, into both the method of examination and
into the effect produced by manufacture.

A scientific method of food examination is neces-
sary for food officials in order to determine the
condition of a product, but is not necessary for the
manufacturer, though it may be advantageous. The
latter is in a position to know what enters his fac-
tory and what changes take place in the food until
it reaches the sealed package. He should have no
fear of a method which correlates the findings in the
finished product with that of the material used and
the changes due to treatment.

Undue importance may seemingly be given to the
subject of ketchup, but the principle involved ap-
plies as well to other products.

The fundamental basis for the microscopic ex-
amination of any food product must depend upon
the structure of the material which enters into its
composition. Any attempt to determine an abnormal
condition, such as decomposition, without a knowl-
edge of the normal, must necessarily be of little
value. There is some work which can be done in a
mechanical manner by almost anyone capable of
looking through a microscope, and if the work is
properly supervised, it may have a value, but the
lines along which this can be done are very limited.
Any attempt to apply such superficial methods to
the general examination of food products can not
properly protect the public and may be unfair to the
producer. It has, therefore, been deemed advisable
to incorporate a brief statement concerning the
structure of the tomato before discussing the re-
sultant products.

MICROSCOPIC EXAMINATION 33

HISTOLOGY OF THE TOMATO AND OF THE
RESULTING KETCHUP.

STRUCTURE OF THE TOMATO.

Pericarp. The tomato is a typical berry, the
ovary wall, free from the calyx, forming the fleshy
pericarp, which encloses chambers filled with a clear
matrix, containing the seeds. The pericarp consists
of an outer tough membrane, the epidermis, a more
or less thick layer of parenchyma tissue, the pulp,
and an inner thin, delicate membrane, the lining
layer of the loculi or chambers in which are the
seeds. The epidermis consists of a single layer of
cells which have a very thick continuous cuticle
about one-half of the diameter of the whole cell.
The cuticle differs in chemical composition from the
rest of the cell walls, being impervious to water,
and resisting rotting longer than do the cellulose
walls. As it is continuous over the whole of the
fruit, the skin can be readily separated from the
other tissues. Hot water facilitates the removal of
the skin, as it causes the cellulose of the walls to
swell more than the cuticle, producing an effect as
of shinkage of the outer wall and a consequent
curling of the skin. The radial walls of the epi-
dermis are short and irregularly thickened, leaving
pits in the walls, and giving them a beaded ap-
pearance. The skin constitutes about 1.3 per cent
of the tomato.

The layers of parenchyma just beneath the epi-
dermis are closely united and flattened, with their
adjoining walls irregularly thickened. On account
of their position, they are called hypoderm. In the
tomato the hypoderm consists of two or three layers
of cells, parts of which usually separate with the
epidermis. Below these cells are the thin-walled
parenchyma cells, which are approximately globular,
vary considerably in size, are very loosely held to-

34 KETCHUP

gether, and have many intercellular spaces. These
cells constitute the mass of the pulp, and with the
juice constitute 96.2 per cent of the tomato.

The layer of cells which lines the chambers has
the typical leaf epidermal structure, the wavy out-
lines, the hollows and protuberances of adjoining
cells fitting one another so that they form a con-
tinuous layer. They are also flattened laterally. The
structure can be understood readily when it is
known that the pericarp is really a metamorphosed
leaf and that the outer side of the leaf forms the
inner wall of the ovary.

The chambers of the tomato are filled with a
clear, slimy matrix in which the seeds are embedded.
The matrix consists of parenchyma cells of various
sizes and with delicate walls, and a small nucleus.
The cells are massed loosely, and can be separated
readily. In those cells, as well as in the wall cells,
are starch grains which vary in size, being round
or approximately so, and having the hilum, when
visible, a straight line to one side of the center.

Coloring Matters. In the parenchyma cells are
two coloring matters, one yellow, which is amor-
phous in structure, and the other red and of crystal-
line form. The sap contains a yellow color in
solution which differs in its reactions from those in
the pulp.

Bed Color in Tomatoes. The red coloring matter
in tomatoes is in the form of Irregularly shaped
crystal-like chromoplasts, which occur in masses of
various sizes. They are present in largest amounts
usually in the protoplasm which lies close to the
ectoplasm and in that surrounding the nucleus.
They vary from sharp, bright-colored forms to those
more or less blunt in outline, and dull in color.
They may be situated largely in the periderm, the
soft parenchyma beneath the periderm, or through
the whole mass of the parenchyma with the excep-
tion of the matrix surrounding the seeds in the

MICROSCOPIC EXAMINATION 35

loculi. In tomatoes having the color in the periderm
a considerable amount is lost by adherence to the
skin. The chromoplasts are not affected by rotting
to the same extent as are the other constituents of
the cell; they can be found floating free in the
debris from rotted cells, still retaining considerable
color. They lose their color gradually, in some
varieties much more rapidly than in others. In
stored pulp which has fermented, the color may be
faded to a dull yellowish brown. In tomatoes in-
tended for ketchup where a bright red color is
desirable, care should be used in the selection of a
variety having the chromoplasts bright, properly
oriented, and in sufficient quantity.

Vascular Bundles. In the pulp of the tomato are
found strands of vascular tissue, entering from the
stem, and dividing and ramifying through the soft
pulp. These consist of long tubes with thin walls,
some of which have a strengthening band in spiral
form on their interior walls, the associated cells
being without any special marking. The strands
vary in size from those having a few tubes to those
having a large number.

Seeds. ..The seeds of the tomato are small, flat-
tened, yellow bodies covered by a clear gelatinous
membrane. Their peculiar characteristic is the out-
growth of hairs of varying lengths. The seeds con-
stitute about 2.5 per cent of the weight of the
tomato.

STRUCTURE OF KETCHUP.

Although the tomato pulp is broken into fine
particles by the action of the cyclone, and the skin
and seeds are removed by the fine sieves, pieces of
the various tissues can be readily identified. The
skin and seeds have characteristics which would
serve to distinguish them from similar parts of
other vegetables which might be used for adultera-
tion, but particles of skin and hairs from the seeds

36 KETCHUP

are rarely found. The distinctive features which
can be relied upon are the red, irregularly-shaped,
chromoplastic bodies in the parenchyma cells, and
the peculiar wavy-outlined cells of the lining layer
of the chambers. As nearly all young vegetable
tissues have spiral vessels in their vascular strands,
these are not distinctive, except that they might
differentiate similar tissues of different size. There
is very little starch in mature tomatoes, and more-
over, as the cooking causes the starch to swell and
lose its structure, the starch could not be used for
identification.

Good ketchup made from whole tomatoes, in spite
of the minuteness of the particles, has a clean ap-
pearance, and can be readily distinguished from poor
ketchup. All ketchup will have some micro-organ-
isms present, as it is practically impossible to free
the tomatoes from them in the washing, but the
number is very small in some of the best, in the
manufacture of which careful washing and sorting
have been done. The poorer the ketchup, usually,
the greater number of organisms — bacteria, yeasts,
and molds; sometimes one form predominating,
sometimes all three being in great abundance, this
latter condition usually prevailing in the poorest
ketchup, where more or less rotting has occurred.

As the tomato pulp is a favorable medium for
certain organisms, these will develop first, and it
has also been determined that while one organism is
developing vigorously, others present are checked
until the activity of the first ceases. Then again, as
the composition of the pulp is being altered by the
development of the organisms, the changes induced
render it a more suitable medium for other organ-
isms which are present but held in abeyance, so that
pulp which has been allowed to stand for some time
will usually have present not only a large number,
but also different kinds of organisms.

MICROSCOPIC EXAMINATION 37

CHANGES PRODUCED IN PULP BY ROTTING.

When tissue is held and allowed to rot spon-
taneously, the pulp is decomposed into a granular,
watery mass. The cells beneath the epidermis are
the finest and dryest in the sound tomato, consider-
able pressure of the cover-glass being required to
separate them for examination. Even when forced
apart, the cells retain their shape. They contain a
delicate semi-transparent protoplasm with a rather
large nucleus surrounded by protoplasm and having
strands from this mass connect with the protoplasm
lining the wall. Pieces of the same tissue, on having
the skin removed so as to expose the broken tissue
to the air, were covered with mold in one day and"
in three days so badly disorganized that the cells
separated with the weight of the cover-glass. The
cells were transparent, the walls collapsed into a
wrinkled mass, the protoplasm had disappeared,
except a skeleton of the nucleus, but the red chrorno-
plastic masses were intact. The middle lamella of
the cells is the part which dissolves first, allowing
the cells to separate and causing the walls to become
thinner. The cell cavity is often filled with bacteria,
so that the effect of the rotting can not be seen until
the cells have been washed thoroughly. These bac-
teria have been mistaken for the particles left by
the decomposition of the cell contents. The vascular
bundles are surrounded usually by small paren-
chyma cells which do not separate readily from the
strand in the healthy tissue, but in the decayed
tissue the vessels can be seen clearly, free from
other tissue. In advanced stages of rottenness the
walls of the vessels may be dissolved, leaving only
the spiral thickening, and the parenchyma tissue
crumbled into powder-like fragments. The parts of
the tomato which resist rotting the longest are the
skin, which may be washed clean of adhering par-

38 KETCHUP

tides, the spirals of the vessels, and red particles
of the chromoplasts.

The conditions found in the rotted sections and
pieces of tomato can be distinguished in the poor
ketchup and these factors, together with the large
number of organisms present, serve for purposes of
differentiation.

ORGANISMS IN KETCHUP.

Tomato pulp furnishes a medium suitable for the
development of many organisms, as it contains all
of the necessary food elements. The raw pulp has
an acidity of from 0.2 to 0.4 per cent usually, though
there may be variation due to fermentation and other
causes. On account of its mild acidity, it is espe-
cially suitable for the development of many yeasts
and molds, and some forms of bacteria, consequently
there is present a varied and abundant flora if the
pulp be held for an appreciable time before using,
or if it has been made from tomatoes not properly
sorted and washed. Where the black rot occurs on
tomatoes, the tissue is hardened like cork, and if not
removed on the sorting belt, is broken into small
pieces by the cyclone, and appears as black specks
in the ketchup, these being readily perceived by the
naked eye. The white rot forms soft spots, which,
though not so prominent as the black, carry much
more contamination, as, apart from the bacteria,
yeasts, and molds present, they are often swarming
with Protozoa. These are not ordinarily recognized
in the ketchup, as a chemical or physical shock
causes them to contract, assume a spherical shape,
and become motionless. In this condition they re-
semble the immature conidia of some of the molds.
Rarely only one organism predominates in pulp from
rotted fruit, then the rot consisting of a nearly pure
culture. In all cases of soft rot, there is much more
contamination carried, as the organisms are small
and a greater number present in a given area.

MICROSCOPIC EXAMINATION 39

Whenever the inner tissue of tomatoes is exposed,
organisms develop rapidly, the forms varying with
the locality and the conditions in the pulp. Some of
these organisms may survive the treatment of the
pulp when converted into ketchup, or the original
organisms may be destroyed, and a different set gain
access and develop, but in either event all the organ-
isms alive or dead which were present at the period
of manufacture are found in the ketchup. It has
been noted that certain brands of ketchup have pre-
dominating organisms present which are practically
constant from year to year.

A method for the microscopic examination of
ketchup in order to determine the number of organ-
isms present is described in Circular No. 68, Bureau
of Chemistry. It consists in an adaptation of a
method used in examining blood in physiological and
pathological work, and of yeast in the brewing,
wine-making, and distilling industries. The outfit
required consists of two parts, the microscope and
the counting chamber, each with minor accessories.
The optical outfit recommended for food examina-
tion consists of a microscope with eye pieces and
objectives which will give approximate magnifica-
tions of 90, 180, and 500 diameters. It is advised
that these magnifications be obtained by using 10
mm and 8 mm apochromatic objectives, and x6 and
x!8 compensating oculars (x6 ocular and 16 mm
objective equals x90; x6 ocular and 8 mm objective
equals x!80; and x!8 ocular and 8 mm objective
equals x500), higher objectives being impracticable
on account of their short working distances. This
equipment is adequate for working upon blood or
yeast, but is wholly inadequate for bacteriological
work, except that of the simplest character and
under conditions quite different from those found
in ketchup and other food products.

The counting apparatus or chamber recommended
is known as the Thoma-Zeiss haemacytometer, named

40 KETCHUP

from the designer and maker. The apparatus con-
sists of a heavy glass slip, on which is cemented a
glass 0.2 mm thick, having a circular hole in the
middle. In the center of the hole is mounted a
smaller disk 0.1 mm thick, leaving an annular space.
In the middle of the small inner disk are etched two
sets of twenty-one parallel lines which cut each other
at right angles. The drop of liquid to be examined
is placed on this square, after which it is covered
with a specially heavy cover-glass, which, if perfect
and adjusted so closely that Newton's rings appear,
gives a layer of liquid 0.1 mm in depth. The drop
to be examined must be so small that it remains in
the middle of the chamber, but in contact with the
cover-glass and bottom of the cell. Each side of the
ruled square is 0.1 mm, and as there are 20 spaces
on a side, there is a total of 400 small squares, the
depth being 0.1 mm, thus the cubical content of
each is 1-4,000 c mm or 1-4,000,000 cc. For convenience
in counting, every fifth space is sub-divided. Other
counting chambers have been devised based on the
same principle, but varying chiefly in their rulings
for convenience in counting.

The other apparatus recommended consists of a
50 cc graduated cylinder, slides, and cover-glasses.

Since the counting chamber has been used exten-
sively in blood examination and in yeast work, a
brief description of the technique as followed in the
latter may serve to give a better understanding of
its limitations. First, in the preparation of the
sample, the cylinder and flasks for mixing, and the
pipette must be absolutely clean. The liquid to be
examined is shaken thoroughly and then the meas-
ured sample withdrawn as quickly as possible to
prevent the cells from settling and diluted with
weak sulphuric acid (about 10 per cent), which pre-
vents any further development of cells, and also
aids both in the separation of the cells from one
another and in their suspension — the latter factor

MICROSCOPIC EXAMINATION 41

being important when only a single drop is taken
for examination. When counting blood cells, a nor-
mal or other salt solution is used so as to have the
specific gravity of the diluent approximately that
of the blood serum. The dilution is made as low
as possible, since the number obtained in the count
has to be multiplied by the dilution co-efficient, and
any errors made are increased proportionately. A
slight error when multiplied by the factor 4,000,000,
the unit for each square, becomes very large in the
total. The sample is shaken very thoroughly after
the diluent is added, a drop of the liquid taken by
means of a pipette, placed in the center of the
counting chamber, and the cover-glass put in place.
The withdrawal of the pipette and the transference
of the drop to the chamber are done as quickly as
possible to prevent the cells from sinking. The
determination of the number of blood corpuscles,
yeasts, or other cells in one cubic centimeter, the
unit of volume generally used, will depend upon the
average found in a number of squares. The number
of squares to be counted is determined by making
counts until a constant average is obtained, for if a
true average is not obtained, the counting, naturally,
is of no value. If the mounts do not show uniform-
ity in the field, they are repeated.

In using the counting chamber for counting yeast
cells and blood corpuscles, for which it was origin-
ally devised, the bodies to be examined are fairly
large, well defined, and suspended in a fairly clear
liquid, usually of rather high specific gravity. Even
with these favorable conditions, the work must be
done by observing the most careful technique in
order to get relative results, which will be of value,
and they are absolutely useless if any detail has
been slighted or neglected. In attempting to adapt
the method to food products, very different condi-
tions are encountered — conditions which are opposed
to obtaining accurate results. Food products, like

42 KETCHUP

ketchup, consist of a mixture of solids and liquids
in which are various forms of organisms, the latter
in varying condition, due to their environment and
treatment, as well as to stages of disorganization.

In estimating the number of yeasts and spores in
pulp or ketchup, the Thoma-Zeiss counting chamber
is used and the mount observed under a magnifica-
tion of 180 diameters. To prepare the sample, 10 cc
of the material has 20 cc of water added and is
"thoroughly mixed." Before taking a drop for ex-
amination, the sample is allowed to rest for a "mo-
ment" to allow the "coarsest particles" to settle.
This step in the technique is not as clear as could
be desired, for what might be considered as "thor-
oughly mixed" by one microscopist as a half dozen
shakings of the cylinder, might not be so construed by
another even with sixty shakings. As the material
consists of both solids and liquid, this is a very
important detail, as it may easily account for some
of the wide differences in results obtained by differ-
ent workers on the same sample. In a bulletin*
dealing with the examination of solid foods, the
following statement occurs relative to the shaking
in order to be able to obtain the bacterial condition:
"The longer the shaking, the more perfect was the
diffusion of particles. It could not, however, be
continued beyond a comparatively short period of
time, because of the multiplication of organisms.
With the quantities of tissue above stated, ten min-
utes' shaking was selected as a happy medium
between an undesirable multiplication of the organ-
isms on the one hand and the retention of the
organisms by the tissue and the consequent lowering
of the numbers found, on the other." The organisms
in pulp or ketchup are dead, or, if alive, do not
possess such phenomenal power of multiplication,
therefore, the shaking should be conducted with
sufficient energy and for a sufficient time to insure

*No. 115— Bureau of Chemistry, Dept. of Agr.

MICROSCOPIC EXAMINATION 43

their separation from the tissue. Furthermore, "let-
ting stand for a moment" may mean thirty seconds
or two or three minutes to different persons.

In all biological work involving the counting of
organisms, either by the plate or direct method, in
the case of yeast, the operator works as rapidly as
possible to prevent the organisms from settling, so
as to have them evenly distributed in order that he
may obtain an average sample. A pipette is used
for removal of a drop of the liquid and the drop
placed in the chamber as quickly as possible to
prevent settling. No directions are given as to how
the drop of the diluted pulp or ketchup is to be
removed to the chamber, so that a stirring rod or
other apparatus is frequently used, as the solid
particles interfere with the use of a fine pipette. If
the rod be inserted to the bottom, or nearly to the
bottom of the mixture and withdrawn slowly and
another withdrawn somewhat rapidly, a difference
of fifty per cent or even more may result in the
count. It is not possible for different operators to
use pipettes, glass rods, pen knives, toothpicks, and
matches for drawing the samples, and get compar-
able results. It has been found that in (all of these
have been seen in use) the counting of the organisms
in pulp and ketchup, some persons use distilled
water, others tap water, some clean their measuring
flasks and pipettes, while others rinse them, so that
naturally reports are made of such varying numbers
that manufacturers do not look upon the method
with confidence. It is only by using uniform meth-
ods and the same care necessary for other biological
work that even an approximation can be made.

STRUCTURE OF THE TOMATO.

To obtain the number of yeasts and spores in the
sample, a count is made in one-half of the ruled
squares. Two hundred squares represent a volume

44 KETCHUP

equivalent to 1-20 c mm, which, multiplied by the
dilution, would give the number in 1-60 c mm.
It is stated that it is believed that it is possible for
manufacturers to keep the count below 25 per 1-60
c mm.

The same mount is used in estimating the bac-
teria, but the x!8 ocular used so as to increase the
magnification to approximately 500 diameters. The
"number in several areas, each consisting of five of
the small squares, is counted." Nothing is said as
to the order of the five squares, whether in a row
or other arrangement, nor what number constitutes
"several." The average number found in five squares
represents the number in 1-800,000 part of a cc,
and this multiplied by 3, for the dilution, would
make the factor 1-2,400,000 for a cc. It is stated
that it is believed that it is possible for manufac-
turers to keep within 12,500,000 bacteria per cc in the
pulp and 25,000,000 in ketchup. The number present is
expressed in terms per cc though the yeast and
spores are expressed in 1-60 c mm. Possibly bac-
teria to the lay mind mean something dangerous, so
by expressing the numbers in millions they appear
appalling. Yeasts and spores are not so generally
associated with dirt and disease so that by giving
them a small unit, only 1-60,000 part of a cc, they may
seem much less offensive. If the mind is capable of
conceiving what is meant by millions per cc for
bacteria in one case, there seems to be no good
reason why the same unit of volume should not
hold for the other.

To estimate the number of molds present, a drop
of the undiluted pulp or ketchup is placed on an
ordinary slide and the ordinary cover-glass pressed
down until a film of 0.1 mm is obtained. The
directions state that after some experience this can
be done, but do not state how one's efforts may be
directed to obtain this result. It is apparent that
by experience in. comparing a measured amount with

MICROSCOPIC EXAMINATION 45

a judged amount that the tendency would be toward
accuracy, but in this case there is no measured
amount for comparison, except the diluted drop in
the counting chamber. Some workers have placed
thin cover-glasses under the edges of the mount so
as to have something to help in estimating the thick-
ness of the film, but as the thinnest ordinary cover-
glasses vary from .12 to .17 mm in thickness, the
error varies 20 to 70 per cent from that required.
One manufacturer in advertising No. 1 cover-glasses
states that they vary from 0.13 to 0.17 mm, while an-
other states they vary from 1-200 to 1-150 of an inch
(0.127 to 0.169 mm). Careful checks show that it is not
always easy to get exactly .1 mm on the specially
prepared counting chamber; that unless the cover
be placed with care and pressed uniformly on all
sides until Newton's rings appear, a variation of ten
per cent or more in thickness may occur, and with-
out such a guide the error becomes greater. The
micrometer screw adjustment on the microscope can
be used to help in determining the thickness, but
none of the workers observed has used this refine-
ment.

The examination for mold is made with the x6
ocular and 16 mm objective, giving a magnification
of approximately 90 times. About 50 fields are sup-
posed to be examined and the result expressed in
terms of the per cent in which mold was found.
It Is stated that it is believed that manufacturers
can conduct their operations so that mold will not
be present in more than 25 per cent of the fields.
There are, therefore, three units in which to express
the results: bacteria in cubic centimeters, yeasts and
spores in one-sixtieth of a cubic millimeter, and
molds in percentage of microscopic fields.

Aside from the errors which may occur in the
manipulation of the purely mechanical part of the
technique, there are other considerations which affect
the accuracy of the results. First, the differentiation

46 KETCHUP

between organisms and tissues is not considered
possible by most pathologists and bacteriologists
without differential staining. Even in such simple
examinations as those for diphtheria and tubercu-
losis, a stain is required. In foods the particles of
the plant tissue and the organisms are not so
different that they can be clearly separated without
using similar technique. It is possible to make
some separation, but not with accuracy. Threads of
protoplasm may be mistaken for bacilli; the granu-
lar contents of a cell for cocci, yeasts, or spores;
bits of cell wall for hyphae under the magnifications
given, and the results obtained be high or low,
depending upon the personal ability of the operator.
Each error magnified by the enormous factor used
in calculating the final result naturally gives figures
which may be far above or below the truth. Those
who have had special training in plant structure and
bacteriology are likely to give the higher figures,
while those who have had these subjects as inci-
dentals in a scientific course are apt to give much'
lower ones.

Second. The standard is set for what organisms
shall be counted and those which need not be. It is
said that micrococci need not be counted because of
the difficulty in distinguishing them from "particles
of clay, etc.," and not upon their power to produce
decomposition. When an organism is a coccus and
when rod shaped is not easily settled, even with the
aid of pure cultures and high power objectives.
More than one organism has found a home first in
one group and then in the other, and differentiation
with the low power obtained by an 8 m m objective
is impossible. There are always present some very
large rods, but there may be more very short ones
which may not be counted, and there is nearly always
a diplococcus present, which, with the magnification
used, is difficult to differentiate from a rod. There
are four forms associated with rot and tomato dis-

MICROSCOPIC EXAMINATION 47

eases which have been carefully studied — all rods,
but very small ones. Ps. fluorescence, 0.68x1.17—1.86;
Ps. michiganense, 0.35 — 0.4x0.8 — 1.0; B. carotovorus,
0.7 — 1.0x1.5 — 5; and B. solanacearum, 0.5x1.5. Bacil-
lus subtilis, .7x2 — 8 and some lactic acid forming
varieties are always present. It is clearly a matter
of judgment on the part of the examiner as to which
organisms he will count and which he will not
attempt to count. A personal equation is thus intro-
duced which nullifies the possibilities of scientific
accuracy.

The yeasts and spores are counted together. They
can not be separated under the microscope, neither
can they be differentiated from contracted protozoa
which may be present in large numbers. In counting
these, it is not always possible to distinguish the
smaller yeast cells and smaller spores from the re-
fractive bodies which are formed in some mold
hyphae when these are impoverished, and which are
liberated if thorough shaking of the sample be done.
The yeasts found in pulp and ketchup are more
likely to be "wild yeasts" and these are, as a general
thing, smaller than the cultivated, sporulate more
readily, and have more highly refractive spores.
Then, some of the so-called molds found form minute
conidia and when these and the yeasts are mixed
with the detritus of the tomato and the mass sub-
jected to heat, with the consequent changes, the
accuracy of the count becomes a somewhat problem-
atical matter. A careful examination of the kind
and condition of the hyphae present might assist
materially in making some distinction.

In counting molds, no distinction is made as to
whether a small bit is in the field or a large mass.
In making a mount for molds, the solids generally
tend to stay In the center of the field while the
liquid tends to run to the edge. The fields selected
may therefore give a high or low result determined
by their location. One examiner desiring to favor

48 KETCHUP

the manufacturer may select the outer part for most
of the fields, while another, making the examination
for the buyer, who may wish to make a rejection,
may reverse the operation. Some persons modify the
directions given by counting only pieces which are
one- sixth the diameter of the field, while others use
a smaller fraction. It is easily possible to have one
clump of mold in one field which will be twenty to
thirty times in extent that of another, yet both are
given equal value in the final expression.

Third. No real relation exists between the organ-
isms counted and decomposition, for mere numbers
are not always coincident with putrefactive activity.
A pulp or ketchup may be bad and show less than
30,000,000 bacteria, or it may be good and show
300,000,000. Rotting, or decomposition, may depend
more upon the cocci and the organisms which are not
counted than upon those which are. The only work
done in which microscopical and chemical work were
reported on the same samples appears in Circular
No. 78, Bureau of Chemistry. This was not done
upon samples prepared and kept under control, but
for the most part upon commercial pulp and ketchup.
The results do not show any close relation between
the number of organisms and the lactic acid content
which is given as the measure of decomposition.

Fourth. Bacteria are expressed in numbers per
cc, yeast and spores in numbers per 1-60 c mm. Since
the counting can be done only in the fluid portion,
an error occurs proportional to the number of bac-
teria in or attached to the tissue which cannot be
counted.

The error of assuming that numbers of organisms
alone are a sufficient index of the wholesomeness of
a food product is well illustrated by work on water
analysis. The following statement by an authority
on the subject is illuminative: "The belief is wide-
spread among the general public that the sanitary
character of a water can be estimated pretty directly

MICROSCOPIC EXAMINATION 49

by the number of bacteria it contains. Taken by
itself, however, it must be admitted that the number
of colonies which develop when n given sample of
water is plated affords no sure basis for judging its
potability. A pure spring water containing at the
outset less than 100 bacteria per cubic centimeter
may come to contain tens of thousands per cubic
centimeter within twenty-four to forty-eight hours,
after standing in a clean glass flask at a fairly low
temperature. There is no reason for supposing that
the wholesomeness of the water has been impaired
in any degree by this multiplication of bacteria."*

There are certain steps in the process of manu-
facture which also influence the number of organisms
which may be counted. A pulp may vary from an
unevaporated tomato juice to a concentration which
is represented by an evaporation of a volume of
water up to 60 per cent, and ketchup may vary from
a thin watery consistency to one which is so heavy
that it will scarcely flow from the bottle. It becomes
evident that a method which does not sustain some
close relation to the amount of tomato present would
naturally be deficient as a standard for judging.
For example, a tomato juice with an initial count of
10,000,000 if evaporated to one-half its volume will
have more than twice the number of organisms esti-
mated in the original. The pulp is composed of
both liquid and solids and part of the liquid portion
only is driven off by evaporation, leaving in the
residue a different proportion to the solids. As the
organisms can be counted only in the liquid portion,
it is obvious that with concentration, the number
will be increased at a much greater ratio than will
the reduction of the bulk. A thin pulp with 10,000,000
bacteria may easily be worse than a heavier one with
30,000,000 or 40,000,000, if judged by numbers alone.

*Jordan, E. O. A text-book of General Bacteriol-
ogy. 1908.

50 KETCHUP

The same conclusion is necessarily true for ketchup.
It clearly refutes the argument that a product having
twice as many bacteria as another of the same kind
is more than twice as bad. The effect of recommend-
ing an arbitrary low limit for bacterial content,
irrespective of the consistency of the product, is to
cause manufacturers to pack thin pulp and sloppy
ketchup, and to discourage the more desirable heavy
body. The examination of a very large number of
samples shows that the majority of the heavy pulps
and ketchup upon the market show much higher
counts than the thin ones when the tissues show
good stock in both.

It is not possible to concentrate any pulp to the
consistency of paste and have it pass under the
present method ; that is, considering a product to be
filthy, putrid or decomposed if the bacteria exceed
25,000,000 per cubic centimeter.

There are some soup and ketchup manufacturers
who still follow the draining method for separation
and this is generally done to secure a certain quality
in the flavor. This kind of pulp always shows a
high bacterial count, which is usually ascribed to
fermentation. As the draining can be started in
about twenty minutes, and is nearly always com-
pleted in forty minutes to one hour, there is little
time for fermentation, and yet such a pulp may show
several times the count of the original whole pulp.
The condition is similar to that which takes
place in the separation of cream by gravity. Dr.
John F. Anderson, U. S. Public Health Service,* has
shown that the bacterial content of gravity cream is
about sixteen times that of bottom milk and that
this discrepancy may be much wider. One test is
given in which the cream showed 386 times as many
organisms as the bottom milk. The question logically

*The Journal of Infectious Diseases. 1909. Vol.
6, p. 393.

MICROSCOPIC EXAMINATION 51

arises whether, if a pulp which contains 10,000,000
bacteria per cubic centimeter and is considered
sound, becomes "filthy, putrid or decomposed" when
the same pulp is heavily concentrated and the count
becomes 100,000,000, or a cream is bad when it con-
tains 2,000,000, though the whole milk from which
it was derived contained only 300,000. There should
be a recognized difference in rating a product in
which the number of organisms is influenced by
concentration, and one in which they have developed.
Some very erroneous statements have been made upon
increase of bacteria in pulp while standing. Some
of these have been based upon the academic propo-
sition that reproduction in bacteria may occur every
twenty minutes under perfect conditions of food
supply, freedom of movement, and optimum tem-
perature. Such statements are obviously not based
on experiments with pulp. Assuming that such a
rate of reproduction were possible, a pulp with an
initial start of only 5,000,000 would increase to
10,000,000 in twenty minutes; 20,000,000 in forty
minutes; 40,000,000 in one hour; 80,000,000 in one
hour and twenty minutes; 160,000,000 in one hour
and forty minutes; 320,000,000 in two hours, and
2,560,000,000 in three hours. No food product like
tomato pulp, cider, or grape juice would be usable
in a very short time. To determine the rate of in-
crease of the organisms in tomato pulp, experiments
were made, using sound tomatoes. In each experi-
ment, the tomatoes were divided into two lots, one
lot used raw, the other steamed, the steaming varying
from two minutes' time, just sufficient to slip the
skins, and eight minutes, in which the whole tomato
is softened. Samples were taken at hourly intervals
for the first six hours, then at intervals of twelve
hours, the samples counted by means of the plate
and direct methods. For the plates tomato gelatin was
used with an acidity of 0.3% and .4%, the samples
for the direct count were put in cans, sterilized, and'

52 KETCHUP

counted later. With the lower acidity there were
liquiflers which prevented the counting of some
plates, so that in the later trials the higher acidity
gelatin was used. The count of the molds was not
normal, due to the frequent stirrings, which pre-
vented spore formation, besides injuring the hyphae.

The results varied, some pulps giving a much
higher initial count than others, but they all agreed
in having a comparatively slight increase in the first
three hours, the large numbers which one is led to
expect not being present until the pulp had stood
for at least five hours and under the most favorable
conditions; usually it requires a longer time. The
plates and the direct count agreeing in the general
trend, though the numbers obtained by the two
methods varied. In the pulp obtained from the
steamed tomatoes, the initial count was much lower
in the tomatoes steamed eight minutes, being only
20 per c c in the plates, but the same thing was true
of these in that the increase was very slow at first.
The figures from all the trials, both raw and steamed
pulp, and from the plates and direct counts, show
that the theoretical estimation of the increase of
organisms from the classic twenty minutes required
for reproduction of an organism with the consequent
progression, irrespective of the condition of the or-
ganism at the start, or its environment, will have to
be modified. In the plates all colonies, aside from the
molds, were counted as bacteria, but this would not
give a very large error, as yeast does not reproduce
at the same rate as do bacteria.

The state of comminution of the product deter-
mines to a considerable extent the number of organ-
isms which may be counted. The more finely the
comminution, the greater the number. Two pulps
made from the same material, one run through an
ordinary cyclone and the other through a finishing
machine, will show from 50 to 100 per cent more in
the latter. Coarse pulp and coarse ketchup may be

MICROSCOPIC EXAMINATION 53

inferior articles and yet give the better results by
the direct method. The effect on the mold is even
more marked — filaments and clumps will be torn into
many small particles. The total quantity is not
increased, but it is distributed more nearly per-
fectly and thus occurs in more fields.

In work done on meat to determine the technique
which should be employed in the bacteriological ana-
lysis, comparison was made between shaking the
sample and grinding it in a mortar with sand. In
the three samples reported, the shaking gave only
3, 12, and 13 per cent, respectively, of those obtained
from grinding.*

A finely comminuted pulp was vigorously shaken
for definite times and samples taken as quickly as
possible after the tenth, fiftieth, one hundredth, and
two hundredth times shaken. The results were as
follows :

Yeast and

Mold in
Per

No. Times

Bacteria

Spores Per

Cent of

No.

Shaken.

Per c. c.

1-60 c. c.

Fields.

1

10

31,020,000

22

80

2

50

50,040,000

42

76

3

100

84,730,000

106

92

4

200

116,640,000

116

100

In line with this are the results obtained before
and after shipping long distances. When the goods
have been handled roughly during shipping the
count is much higher.

The length of time elapsing after manufacture
until the counting is done also has an effect. Pulp
put up in the fall will show one count and the same
pulp the following season a different count. This
difference is not due to any multiplication during

*Weinzirl, John and Newton, E. B. American
Journal of Public Health. Vol. IV, No. 5.

54 KETCHUP

storage, but to the fact that the organisms separate
from the tissues more readily. The difference made
in the counting from this treatment is not as marked
as that produced by the other factors already treated,
but is sufficient to cause a change in the count.

It is known that the surface of plants is covered
by a variety of bacteria and other fungi that remain
dormant under unfavorable conditions, but that these
become active when the food which is invariably
present is rendered available by access of moisture,
either dew or rain, or the rupture of the host, etc.
These will vary in numbers with the season, wet or
dry, hot or cold, in different sections of the country,
and, in the case of the tomato, with the variety of
the fruit ; whether perfectly smooth or with a slight
bloom; whether irregular or regular in shape; and
whether slightly green with a firm skin or fully
ripe. These are all factors that have an influence
and should not be overlooked. Some packers have
already learned that by packing tomatoes which are
colored, but not really ripe, that the count will be
lower, and as such a practice extends, it means the
use of poorer material instead of that which is
properly developed and with the normal flavor.

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