It was formerly customary, and is still the practice of some
manufacturers of tomato pulp, to discard a portion of the juice of the
tomatoes. Some manufacturers, especially in the preparation of pulp
from tomato trimmings, allow the trimmings to pass over a colander
and thus separate the free juice, which is discarded. Others allow
the product of the cyclone to stand for a time in tanks and then
discard the clear juice which settles in the bottom of the tanks. Both
practices are wasteful and have generally been discontinued. Some still
adhere to one or both, however, and it was thought best to make the
matter the subject of study.
Some discard the juice because of the belief that it consists of
nothing but water and is valueless. Some are of the impression that the
juice separated from the trimming stock before straining takes on a
brown color during evaporation which would interfere with the red color
desired in the finished product, if allowed to go into the pulp. Some
recognize the value of the juice, but believe that the expense of its
evaporation would not be warranted by the increased quantity of pulp.
Some have not measured the juice discarded and greatly underestimate
its volume.
With the view of determining the approximate value of the material
discarded in this manner, a batch of material, fresh from the
cyclone, was divided into two portions, one of which was immediately
concentrated to form a pulp, and the other was allowed to stand about
20 minutes when a clear liquor had separated at the bottom. This clear
liquor was then removed and the remainder evaporated until the desired
consistency was obtained.
Samples of the finished pulps, of the raw product from which each
was prepared and of the clear liquor, separated from the second one,
were preserved by sealing in cans and processing. These samples were
numbered as follows:
702—Product from the trough under the second cyclone, or finisher.
703—Clear liquor, which separated at the bottom of the tank, after a
portion of 702 was allowed to stand. This formed about one-fourth
of the entire product of the tank.
704—Drained residue from 703.
705—Finished pulp obtained by concentrating 704.
706—Finished pulp obtained by concentrating 702.
These samples were examined with the results given below.