There is a growing tendency to give increased attention to the quality
of tomato pulp. The tomatoes should be ripe and well colored. Green
tomatoes or tomatoes with green portions not only do not have the
requisite amount of red coloring matter but they contain material
which masks and dulls the color of fully ripe tomatoes. There is a
difference of opinion among successful manufacturers of pulp regarding
the relative color of pulp manufactured after hot or cold cycloning.
Some maintain that a better color is obtained by cycloning hot. Others,
apparently equally skilled and able to manufacture an equally good
product, maintain the reverse. Much depends on the control of the
cyclone—the setting of the paddles and the speed at which they are
operated.
The evaporation should be as rapid as possible. The operation of the
kettles in such a way that the pulp burns on the kettles or on the
coils damages the flavor of the product and impairs its color. The
pulp should be cooled promptly after processing, or if that is not
practicable should be stacked loosely so that the cans will have ample
ventilation until they are entirely cooled.
Pulp packed in five-gallon cans is rarely processed. It should,
however, be filled into the cans at a temperature of at least 180° F.
It is best to give pulp in No. 10 and smaller size cans a short process
in boiling water. With pulp filled at 180° F., ten or fifteen minutes
is a sufficient cook. Pulp filled at lower temperatures or which is
allowed to partially cool before processing requires a longer process.
In order to protect the color it is best to water cool No. 10 cans of
pulp after processing. Pulp in cans of any size should not be stacked
solid while it is still hot. The metal of the can has a bleaching
action on the pulp and this is greatly increased if the pulp is stacked
hot or stored in a hot warehouse. If stacked while excessively hot,
stack-burning may occur with consequent darkening of the pulp.
As indicated above, there is a considerable difference of opinion among
successful manufacturers of pulp regarding the details of manufacture
necessary to secure the best results. It is probable that different
conditions call for different methods of operation. At any rate, all
successful manufacturers are agreed that the color of the pulp is an
important index to its quality and greatly influences its commercial
value. The flavor of pulp is also an important criterion and is
considered by many buyers in forming an estimate of the value of pulp.
A scorched taste or a flat flavor show that the manufacture of the pulp
was not adequately controlled and impairs the commercial value of the
product.
Color and flavor commonly go together. The same manufacturing methods
which yield a product of high color are likely to give a product of
superior flavor.