The results obtained by the examination of 33 samples of whole tomato
pulp are given in Table 2. The concentration of the samples varies
from unconcentrated pulp as it runs from the cyclone to pulps of very
heavy consistency. This table contains the data from which Tables 4 and
5 were calculated, although during the season a partial analysis was
made of a large number of other samples, and the data secured therefrom
were in all respects confirmatory of the relations calculated from
Table 2.
[1] This chapter is taken largely from an article by Bigelow and
Fitzgerald, published in the Journal of Industrial and Engineering
Chemistry, 1915, vol. 7, page 602.
In addition to the data obtained by the various determinations, Table 2
gives the relation between the results of the determinations for each
individual sample. For instance, the ratio of pulp solids to filtrate
solids (pulp solids divided by filtrate solids) varies in the different
samples from 1.091 to 1.154, and, with the exception of two samples,
it varies from 1.100 to 1.145. The average of the 33 samples was 1.12.
The relation of insoluble solids to total solids (expressed as per cent
of insoluble solids in total solids) is shown in Table 2. Considering
the variations in the methods employed by different manufacturers in
the preparation of tomato pulp, the per cent of insoluble solids in the
total solids as shown by this column is closer than we might expect,
varying in most of the samples from 11 to 14 per cent.
The per cent of sugar in the soluble solids, as shown by Table 2,
varies in most of the samples from 50 to 55 per cent. This figure
cannot be expected to be constant in different localities and in
different years.
The acid, estimated as citric, constitutes in most of the samples from
9 to 10 per cent of the soluble solids.
Of especial interest is the refractive constant of the filtered liquor,
shown in the last column of Table 2. The refractive constant of the
various samples is much more uniform than might be expected from a
product of this nature.
Table 2 is chiefly interesting as affording the data from which Tables
4 and 5 were calculated. The uniformity of the relations shown in
Table 5 is such that it is usually possible from one determination on
the filtrate and the determination of solids in the pulp by drying to
distinguish pulp made from whole tomatoes from that made from trimming
stock. For instance, if the specific gravity or index of refraction of
a filtrate prepared from a pulp of unknown origin, and the per cent
of solids in the pulp by drying, do not agree approximately with the
relation between these determinations as shown in Table 5, it may be
assumed that the sample was not prepared from whole tomatoes, or that
some other substance, such as salt, has been added. Moreover, trimming
stock pulp rarely conforms to the relations found in whole tomato pulp.
For instance, the insoluble solids are usually higher and the acid
lower in trimming stock pulp.