Ketchup: Methods of Manufacture; Microscopic ExaminationBitting, K. G. (Katherine Golden)
Science
Ketchup: Methods of Manufacture; Microscopic Examination
Bitting, K. G. (Katherine Golden)
Ketchup
The density of the ketchup is left usually to the judgment of the chef,
who depends upon the appearance 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 is
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 machines. The former is suitable for thin ketchup. The
resultant product gives the best possible appearance 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 capacity 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 temperature as is practicable,
about 165 to 170 degrees F. If the temperature is higher than this, the
possibility 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
contents 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.
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.
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