The question of how long the ketchup should keep after opening the
container in order to satisfy the ordinary requirements of consumption
was also studied. A local restaurant, serving about two hundred meals
and using from one-half to a gallon of ketchup daily, was supplied with
the same kind of ketchup used in the experiments, as were also some
families. Instructions were given to use the ketchup as they would
ordinarily, with the result that none reported any loss from spoilage.
To determine how long the ketchup would keep after opening, 8 bottles
from each of the first 9 experiments were kept in the kitchen at
a temperature of about 72° F., 5 were kept in an incubator at a
temperature of 95° F., 5 were kept in the laboratory at a temperature
of about 67° F., and 4 were kept in an inclosed porch where the
temperature ranged from 30° to 60° F. This made a total of 198 bottles.
No precautions, other than those of ordinary cleanliness, were taken
in opening the bottles, as it was desired to determine the keeping
properties under conditions of general usage. The first set of bottles
was opened November 5, immediately on being received at the laboratory,
all of the ketchup having been kept at the factory until the experiment
begun in September was completed. The bottles were covered loosely with
a metal cap and observed daily, a record being kept of the date and
character of spoilage.
The results showed that the differences in the time and temperature
of processing had little, if any, effect in checking the spoilage;
neither did the use of acetic acid or oil extracts. The most important
precaution in checking the spoilage after opening seems to be to keep
the ketchup cool. This is shown by the average number of days which
elapsed before spoilage occurred in the sets kept under different
temperature conditions. For those kept in the kitchen the average
number of days was six, the minimum three, and the maximum eleven.
Those in the incubator kept for an average of five days, with a minimum
of two days, and a maximum of eight. Those in the laboratory had an
average of eight days, the minimum being four days and the maximum
twenty-two. Those kept in the porch lasted on an average twenty-seven
days, a minimum of twelve days, and a maximum of fifty-eight.
These figures show the definite relation of temperature to spoilage
under the conditions of ordinary use. In making the observations, the
metal cap was removed each day, but no ketchup was poured off. The
spoilage in all cases was due to mold, and usually this formed in the
neck of the bottle where the ketchup had splashed, or at the junction
of the ketchup with the bottle. The spoilage was recorded as soon as
the slightest growth appeared. In actual use if the neck were wiped
out when the ketchup had been used and a growth of mold removed on its
first appearance with some of the proximate ketchup the time before
spoilage occurred could be prolonged. In these experiments the attempt
was made to determine how soon growth appeared under the various
conditions of temperature named.
The unopened bottles of ketchup were kept in a basement room, the
temperature of which is fairly constant, being about 70° F. This is
approximately the condition in a grocery where the ketchup is kept on
the shelves. Another set of samples from the run of September, 1907,
was opened February 11, 1908, to determine if storing in a warm room
before opening had any effect on the length of time preceding spoilage.
Four bottles were taken from each of the first 9 experiments to make
up each of three sets, one of which was kept in the kitchen, one in
the incubator, and one in the porch, making a total of 108 bottles. The
average number of days for those kept in the incubator was four, the
minimum two, and the maximum six. The average number of days before
spoilage in the kitchen was five, the minimum being three and the
maximum nine. Those kept in the porch gave an average of twenty-three
days, the minimum number being eighteen days and the maximum
seventy-three days. Thus it is seen that the ketchup lasted nearly five
times as long at a temperature of 30° to 60° F. as it did at 72°; and
also that when ketchup is kept in a warm place before opening, spoilage
occurs somewhat sooner, the average for the fresh samples opened under
the same conditions being one day more with the incubator and kitchen
samples and four days more with the porch samples.
A third set of bottles of the ketchup was opened on June 6, 1908, or
two hundred and sixty-five days after manufacture. They had been kept
in a basement at a temperature of about 70° F.
One set was placed in the incubator at a temperature of 95° F., one
set in the kitchen at about 82° F., and one set in the refrigerator
at 46° F. The weather was warm and the conditions favorable to the
spoilage of fresh foods. The minimum time for spoilage in the incubator
was two days, the maximum time four days, and the average time three
and two-tenths days. The minimum time in the kitchen was two days,
the maximum time six days, and the average time four and four-tenths
days. The minimum time in the refrigerator was nine days, the maximum
time nineteen days, and the average time thirteen and sixty-six
one-hundredths days.
These data are grouped in the following table for easier comparison:
_Time of spoilage of ketchup at different temperatures after opening._
OPENED ON NOVEMBER 5, 1907, IMMEDIATELY UPON RECEIPT FROM FACTORY;
MAXIMUM AGE, FIVE WEEKS.
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Place of storage. | Temperature. | Lapse of time before spoilage.
| |-------------------------------
| | Average. | Minimum. | Maximum.
------------------| |----------+----------+---------
| _° F._ | _Days._ | _Days._ | _Days._
Incubator | 95 | 5 | 2 | 8
Kitchen | 72 | 6 | 3 | 11
Laboratory | 67 | 8 | 4 | 22
Porch | 30-60 | 27 | 12 | 58
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KEPT AT 70° F. FOR ONE HUNDRED AND FIFTY DAYS BEFORE OPENING ON
FEBRUARY 11.
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Incubator | 95 | 4 | 2 | 6
Kitchen | 72 | 5 | 3 | 9
Porch | 30-60 | 23 | 18 | 73
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KEPT AT 70° F. FOR TWO HUNDRED AND SIXTY-FIVE DAYS BEFORE OPENING ON
JUNE 6.
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Incubator | 95 | 3.2 | 2 | 4
Kitchen | 82 | 4.4 | 2 | 6
Refrigerator | 46 | 13.66 | 9 | 19
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