Ketchup: Methods of Manufacture; Microscopic ExaminationBitting, K. G. (Katherine Golden)
Science
Ketchup: Methods of Manufacture; Microscopic Examination
Bitting, K. G. (Katherine Golden)
Ketchup
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
completed 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,[4] 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 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 contains 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 proposition that reproduction in bacteria may
occur every twenty minutes under perfect conditions of food supply,
freedom of movement, and optimum temperature. 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 increase of the organisms in tomato pulp,
experiments were made, using sound tomatoes. In each experiment, 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 0.4%, the samples for the direct count were
put in cans, sterilized, and counted later. With the lower acidity there
were liquifiers which prevented the counting of some plates, so that in
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