The quality of the tomato stock is the real important thing. Fresh tomatoes may be used or a fine grade of pulp may be used, and either will make an excellent soup. With poor tomato stock a good soup cannot be made no matter what you do to it. Spicing artistically, and making rich by the use of plenty of good butter, will not make amends for poor quality of tomato stock.
To succeed in making tomato soup the manufacturer must at least make good on the following counts: first, his soup must be palatable, that is, pleasing, to the taste with no lingering unpleasant after-taste; second, it must not be too sweet or too sour; third, it must be uniform in consistency, smooth when poured out of the can, and must not get lumpy or grainy after being in storage a long time; fourth, it must not curdle fresh milk, even though the housewife adds no baking soda when mixing milk with it; fifth, it must be reasonable in price and attractively packed in popular sizes.
Unpalatability
I will discuss these points a little further. What makes tomato pulp unpalatable and what causes an unpleasant after-taste? The most common cause is poor tomato stock, or tomato stock which has been overcooked. Such a foundation for soup will almost invariably leave a lingering unpleasant after-taste in the mouth. Another thing is too much flour, masking the flavor of the tomato and giving it a somewhat “pasty” taste. Another thing is the injudicious use of spices, producing unpopular flavors, or using one spice, such as bay leaves, for instance, in such large proportion that almost every other flavor is masked. None of these defects are rare in tomato soups, and they all cause unpalatability to some extent.
Proper Sweetness
Getting proper sweetness is not nearly so easy as one might suppose. It is not so difficult when the soup is made from fresh tomatoes, although even then every batch must be tasted after all but a few pounds of the sugar is added, and the amount of sugar varied according to the sweetness of the tomatoes. When the weather is moderately dry, with plenty of sunshine, the tomatoes are usually sweet and do not require so much sugar, but tomatoes which ripen during rainy, dark, cold days are not so sweet, and a little more sugar is needed.
When making soup from canned pulp it is necessary to watch the sweetness of the pulp very close, and it may be necessary for the cook to vary the sugar on a 100–gallon batch ten or fifteen pounds during a day’s run. Canned pulp often varies greatly in sweetness, and if held in storage for many months it often loses some of its sweetness on account of the action of living, acid forming bacteria, which may not be present in large amount, but nevertheless, in time, have a noticeable effect on the sweetness of the pulp.
When pulp is purchased for the purpose of making soup its sweetness should be one of the first considerations in passing judgment on it.
Gradual Souring of Pulp
When the soup manufacturer makes his own pulp and works it up into soup during the winter months he will probably find that he will save on his sugar bill if he will pack the pulp in No. 10 cans and sterilize it—at least that part of the pulp which must be held in storage several months. In this way living, acid forming bacteria are killed, and the danger of the pulp losing its sweetness during months of storage is greatly minimized.