Ketchup of uniform color, consistency and taste can be produced only by
controlling the quality and quantity of its constituents. Therefore,
any satisfactory method of control necessitates the determination of
the solids in the batch of cyclone juice before sugar, salt, vinegar
and spices are added. Control, based solely on uniform specific gravity
of the finished product, assures only that the specific gravity is
uniform; it does not assure uniformity in consistency, sweetness,
acidity, or in any other characteristic of the product.
Since, under any specific procedure in a factory, the distinctive
tomato flavor and the consistency of the finished product depend
entirely on the tomato solids, and since about half the final acidity
and sugar content is derived from the same source, the control of the
tomato solid content is especially important.
Fortunately the solids in cyclone juice have a fairly uniform
composition. The ratio of total solids to insoluble solids is fairly
constant, likewise the ratio of sugar to acid. The sugar in cyclone
juice varies from about 42 per cent to 54 per cent of the total solids,
averaging about 50 per cent.
As the consistency or body of ketchup is due chiefly to the tomato
solids, the amount of evaporation necessary to secure ketchup of the
desired consistency from a known volume of pulp measured at the boiling
temperature and of known Brix or specific gravity can be determined
from Table 9, page 56. For instance, if the volume of the boiling
pulp is 800 gallons and the corrected Brix reading of the filtrate is
5.10, it is found from Table 9 that it will be necessary to evaporate
to 423 gallons to secure a ketchup of approximately the consistency
of 1.040 pulp, to 374 gallons for a consistency comparable to 1.045
pulp and to 334 gallons for a consistency comparable to 1.050 pulp.
This evaporation is carried out, of course, with the addition of the
necessary ingredients for the making of ketchup. The amount of these
ingredients can be varied in order to secure ketchup of the desired
flavor.
After having once decided on the amount of ingredients to be used, the
manufacture may be standardized. Supposing for instance on evaporating
800 gallons of partly concentrated pulp of Brix of filtrate (5.10)
to approximately 334 gallons (calculated from the 1.050 column in
Table 9) it has been found that the use of 301 pounds of sugar, 26.7
gallons of 100 grain vinegar, 66.8 pounds of salt and 50.2 pounds
of onions together with spices gives ketchup of the flavor desired.
Dividing the amount of each ingredient by 334, it is found that each
gallon of finished ketchup contains .9 pound of added sugar, .2 pound
of salt, .15 pound of onions, and about 10 ounces of vinegar. After
having determined the amount of each ingredient per gallon of finished
ketchup, it is easy to make a table giving the amount of ingredients
necessary for a given volume of cyclone juice or concentrated pulp of
any gravity. In Table 11 such calculations are made. This table is
based on securing a ketchup having the consistency of 1.050 pulp and
starting with 800 gallons of boiling pulp of specific gravity 1.0220
(Brix reading of filtrate 5.10). Some manufacturers may desire to base
the amount of ingredients on 100 gallons or multiple of 100 gallons of
finished ketchup. This may be done by first making out a table similar
to 9 and then calculating the amount of pulp and other ingredients for
100 gallons of ketchup. This would, however, involve considerable work
as unless the pulp used had a constant specific gravity, a calculation
of the quantity of each ingredient would have to be made for the volume
of pulp for each batch.
TABLE 11.—_Manufacture of Ketchup. Quantity of Constituents to be Added
to 800 Gallons of Boiling, Partly Concentrated Pulp_
=========+==================+=========+===============================
|Filtrate from pulp| | Added constituents
Specific +-------+----------+Volume of+------+---------+-------+------
gravity |Degrees| Specific |finished | |100-grain| |
of pulp |Brix at| gravity | ketchup |Sugar | vinegar | Salt |Onions
at 68° F.|68° F. |at 68° F. | | | | |
---------+-------+----------+---------+------+---------+-------+------
| | | _Gals._ |_Lbs._| _Gals._ | _Lbs._|_Lbs._
1.0154 | 3.50 | 1.0137 | 226.0 | 203 | 18.1 | 45.2 | 33.0
1.0158 | 3.60 | 1.0141 | 232.0 | 209 | 18.5 | 46.4 | 34.8
1.0162 | 3.70 | 1.0145 | 239.0 | 215 | 19.1 | 47.8 | 35.9
1.0166 | 3.80 | 1.0149 | 245.0 | 221 | 19.6 | 49.0 | 36.8
1.0170 | 3.90 | 1.0153 | 252.0 | 227 | 20.2 | 50.2 | 37.8
| | | | | | |
1.0174 | 4.00 | 1.0157 | 258.0 | 232 | 20.6 | 51.8 | 38.7
1.0178 | 4.10 | 1.0161 | 265.0 | 239 | 21.2 | 53.0 | 39.8
1.0182 | 4.20 | 1.0165 | 272.0 | 245 | 21.7 | 54.4 | 40.8
1.0186 | 4.30 | 1.0169 | 278.0 | 250 | 22.2 | 55.6 | 41.7
1.0190 | 4.40 | 1.0173 | 285.0 | 257 | 22.8 | 57.0 | 42.8
| | | | | | |
1.0194 | 4.50 | 1.0177 | 292.0 | 263 | 23.4 | 58.4 | 43.8
1.0199 | 4.60 | 1.0181 | 299.0 | 269 | 23.9 | 59.8 | 44.9
1.0202 | 4.70 | 1.0185 | 306.0 | 275 | 24.5 | 61.2 | 45.9
1.0206 | 4.80 | 1.0189 | 313.0 | 282 | 25.0 | 62.6 | 47.0
1.0211 | 4.90 | 1.0193 | 320.0 | 288 | 25.6 | 64.0 | 48.0
| | | | | | |
1.0216 | 5.00 | 1.0197 | 327.0 | 294 | 26.2 | 65.4 | 49.1
1.0220 | 5.10 | 1.0201 | 334.0 | 301 | 26.7 | 66.8 | 50.2
1.0224 | 5.20 | 1.0205 | 341.0 | 307 | 27.3 | 68.2 | 51.2
1.0228 | 5.30 | 1.0209 | 347.0 | 312 | 27.8 | 69.4 | 52.1
1.0232 | 5.40 | 1.0213 | 354.0 | 319 | 28.3 | 70.8 | 53.2
| | | | | | |
1.0236 | 5.50 | 1.0217 | 361.0 | 324 | 28.9 | 72.2 | 54.2
1.0240 | 5.60 | 1.0221 | 368.0 | 331 | 29.4 | 73.6 | 55.2
1.0244 | 5.70 | 1.0225 | 374.0 | 337 | 29.9 | 74.8 | 56.2
1.0249 | 5.80 | 1.0229 | 381.0 | 343 | 30.5 | 76.2 | 57.2
1.0253 | 5.90 | 1.0233 | 388.0 | 349 | 31.0 | 77.6 | 58.2
| | | | | | |
1.0257 | 6.00 | 1.0237 | 395.0 | 356 | 31.6 | 79.0 | 59.3
1.0261 | 6.10 | 1.0241 | 402.0 | 362 | 32.1 | 80.4 | 60.4
1.0266 | 6.20 | 1.0245 | 409.0 | 368 | 32.7 | 81.8 | 61.4
1.0271 | 6.30 | 1.0249 | 416.0 | 374 | 33.3 | 83.2 | 62.5
1.0275 | 6.40 | 1.0253 | 422.0 | 380 | 33.8 | 84.4 | 63.4
| | | | | | |
1.0279 | 6.50 | 1.0257 | 429.0 | 386 | 34.3 | 85.8 | 64.4
1.0283 | 6.60 | 1.0261 | 436.0 | 392 | 34.9 | 87.2 | 65.4
1.0287 | 6.70 | 1.0265 | 443.0 | 399 | 35.4 | 88.6 | 66.5
1.0291 | 6.80 | 1.0270 | 450.0 | 405 | 36.0 | 90.0 | 67.5
1.0295 | 6.90 | 1.0274 | 457.0 | 411 | 36.6 | 91.4 | 68.6
| | | | | | |
1.0299 | 7.00 | 1.0278 | 464.0 | 418 | 37.1 | 92.8 | 69.6
1.0304 | 7.10 | 1.0282 | 471.0 | 424 | 37.7 | 94.2 | 70.7
1.0309 | 7.20 | 1.0286 | 478.0 | 430 | 38.2 | 95.7 | 71.8
1.0313 | 7.30 | 1.0290 | 485.0 | 437 | 38.8 | 97.1 | 72.8
1.0318 | 7.40 | 1.0294 | 492.0 | 443 | 39.4 | 98.5 | 73.8
| | | | | | |
1.0322 | 7.50 | 1.0298 | 499.0 | 449 | 39.9 | 99.9 | 74.9
1.0326 | 7.60 | 1.0302 | 506.0 | 455 | 40.5 | 101.3 | 76.0
1.0330 | 7.70 | 1.0306 | 513.0 | 462 | 41.1 | 102.7 | 77.0
1.0335 | 7.80 | 1.0310 | 521.0 | 469 | 41.7 | 104.2 | 78.2
1.0339 | 7.90 | 1.0315 | 529.0 | 476 | 42.3 | 105.8 | 79.4
| | | | | | |
1.0343 | 8.00 | 1.0319 | 536.0 | 482 | 42.9 | 107.2 | 80.4
1.0347 | 8.10 | 1.0323 | 543.0 | 489 | 43.5 | 108.6 | 81.5
1.0352 | 8.20 | 1.0327 | 550.0 | 495 | 44.0 | 110.0 | 82.6
1.0356 | 8.30 | 1.0331 | 557.0 | 501 | 44.5 | 111.4 | 83.6
1.0361 | 8.40 | 1.0335 | 564.0 | 508 | 45.1 | 112.8 | 84.7
| | | | | | |
1.0365 | 8.50 | 1.0339 | 571.0 | 514 | 45.7 | 114.2 | 85.7
1.0369 | 8.60 | 1.0343 | 578.0 | 520 | 46.2 | 115.6 | 86.8
1.0374 | 8.70 | 1.0348 | 585.0 | 527 | 46.8 | 117.0 | 87.8
1.0379 | 8.80 | 1.0352 | 592.0 | 533 | 47.4 | 118.4 | 88.8
1.0383 | 8.90 | 1.0356 | 600.0 | 540 | 48.0 | 119.0 | 90.0
---------+-------+----------+---------+------+---------+-------+------
The use of Table 11 gives a ketchup of medium concentration. Using this
as a basis the manufacturer can decide the extent to which he should
evaporate to secure a ketchup of the consistency desired and modify the
table accordingly.
Final concentration of the ketchup is controlled in the same manner as
for pulp, either by a gauged tank or by specific gravity determination.
If we start, therefore, with a given volume of partially concentrated
cyclone juice and determine the solids present, we can in every case
quickly ascertain from the appropriate table the number of gallons of
finished product we should obtain, and the gauge stick or attached
gauge glass will indicate when to stop evaporation in the tank. One
advantage of measuring the original volume at the boiling temperature
is that no temperature corrections are necessary, as both the initial
and final temperature measurements are approximately the same.
The final concentration may be controlled, as stated above, by
determining the specific gravity of the finished product by one of the
methods given under pulp (see page 33 and following). The determination
of specific gravity at this point will probably give more accurate
results than the use of a gauge stick, and is to be recommended for
use with the finished product, provided the added constituents have
been standardized. The method described on page 42 for determining the
specific gravity of hot tomato pulp, may be used for obtaining the
per cent of solids in the boiling cyclone juice in place of the Brix
spindle reading on the filtrate.
Table 11 for controlling the concentration of finished ketchup is
based on the idea that there shall be a definite volume of partly
concentrated pulp in the tank when the inflow of cyclone juice is
stopped and the sample is taken for analysis. In this respect, this
method of controlling the concentration of ketchup varies from the
method described on page 54 for the control of the concentration of
tomato pulp. It is sometimes convenient to secure this definite volume
by filling the tank to a greater height than is desired and evaporating
until the desired volume is secured. When this point is reached the
sample of pulp is taken for specific gravity and steam is again turned
on the tank.
The Abbé refractometer may also be used for controlling the final
concentration of the ketchup. This provides a very simple and quick
method for determining the percentage of solids. It requires but
a few drops of the filtered liquor from the ketchup to make the
determination. The reading may be taken and the calculation made in
one or two minutes’ time by use of Tables 13 and 14.
The table for calculating the solids from the refractometer reading is
Geerlig’s table for dry substance in sugar-house products, and is taken
from the Methods of the Association of Official Agricultural Chemists,
1919. The entire table is not given but only the range over which it
might possibly be desired to use it in the control of the manufacture
of ketchup.
The results by this method are only approximate, but are sufficiently
accurate for manufacturing control. Table 12 gives a comparison of the
solids obtained by drying in vacuum at 70° C. with results obtained by
the refractometer.
TABLE 12.—_Solids in Ketchup Obtained by Drying in Vacuum at 70° C. and
by Abbé Refractometer from Geerlig’s Table_
+------------------------------+
| Solids in tomato ketchup |
+----------------+-------------+
| By drying in | By Abbé |
|vacuum at 70° C.|refractometer|
+----------------+-------------+
| _Per cent_ | _Per cent_ |
| 29.5 | 29.0 |
| 30.0 | 29.4 |
| 32.8 | 32.4 |
| 28.0 | 27.9 |
| 22.0 | 21.8 |
| 27.7 | 28.0 |
+----------------+-------------+
There are several errors in this determination which partially
compensate for each other and give results fairly comparable with
those obtained by drying. The refractometer of course determines only
soluble constituents. Since salt gives a higher refractive reading
than the same per cent of sugar, and since tomato solids give a higher
refractive reading than the same percentage of sugar, and since any
acetic acid of the vinegar is also read as solids on the refractometer,
the total increase in reading due to these different factors nearly
compensates for the insoluble solids of the ketchup.
The variation of the per cent of solids as obtained by the
refractometer from that obtained by drying will depend somewhat on
the composition of the ketchup and in using the refractometer it is
advisable to also determine the solids by drying on a few samples to
obtain the relation between the two figures for that particular ketchup.