A variety of spices is used in the manufacture of ketchup. Among these are cinnamon, cassia, cloves, all-spice, pepper, cayenne pepper, ginger, mustard and paprika. Spices may be used either in the form of whole spices, ground spices or volatile spice oils. Whole spices are thought by some to produce a better flavor. Ground spices, when used, should be secured from a reputable manufacturer, as there is a possibility of adulteration or use of low-grade material in ground products. Volatile spice oils are used to some extent, especially of spices containing large amounts of tannin, where there is liability of discoloration due to the formation of iron tannate during the manufacture of the ketchup. Acetic acid extracts of spices are also used to a limited extent.
The sugar may be added at any time during the making of the ketchup, but is preferably added during the latter part of the cooking. There is less danger of scorching if added at this time. It should be added gradually and scattered over the surface of the cooking ketchup so that it may go into solution more readily.
Vinegar is always added a few minutes before finishing. The acetic acid of the vinegar is volatile, and a large portion of it will be driven off with steam if added at the beginning of the cooking.
Salt may be added at any time during the cooking, but it is best to add it sufficiently soon so that it will be dissolved and thoroughly mixed with the product.
The onions should be added chopped at the beginning of the cook.
Spices, either whole or ground, are generally placed in a bag and added at the beginning of the cook. If the volatile oils are used, they should be added shortly before finishing the ketchup, as otherwise a large amount of them may be carried off with the steam.
FACTORY CONTROL OF THE COMPOSITION OF KETCHUP
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.