CHANGES DURING THE SPOILAGE OF TOMATOES. 



little, lactic acid, and a product prepared from spoiled tomatoes will 

 probably have a low citric acid content (often none) and a high con- 

 tent of lactic acid. 



It will probably be well to say a few words as to manufacturing 

 methods in the tomato-products industry to show just how these 

 spoiled tomatoes get into ketchup and how spoilage may be avoided. 

 In preparing canned tomatoes there are many tomatoes which, be- 

 cause of their small size or other defects, are not suitable for canning 

 purposes. These tomatoes, together with the skins, cores, and pieces 

 of tomatoes from the canning factory, are cooked to prepare a tomato 

 pulp. Many small canneries prepare pulp which is sold to ketchup 

 manufacturers and in many factories pulp is prepared during the 

 busy canning season to be worked up into ketchup during the dull 

 seasons. In both instances it is quite common to store this pulp 

 in barrels for considerable time. It has been conclusively demon- 

 strated that it is ; in practical work, almost impossible to get barrels 

 tight enough to prevent contaminatioh with organisms and con- 

 sequent fermentation during such storage. If pulp must be stored, 

 it should be sterilized in sealed lacquered tin cans (lacquered to pre- 

 vent excessive solution of tin by the tomatoes, which are very active 

 in this respect, probably because of their citric acid content). We are 

 informed by some manufacturers, who have tried 5-gallon lacquered 

 cans for this purpose, that the cost is really less than that of storage 

 in barrels. With proper sorting to exclude decayed tomatoes from 

 the factory, efficient washing, a prompt working up into pulp, and 

 proper sterilization and storage in lacquered tin cans, there is little 

 danger of decomposition in preparing tomato products. 



There are two other processes of manufacture which should be 

 mentioned. In one, the gravity process, the pulped tomatoes stand 

 until the tomatoes rise (due largely to fermentation changes), and 

 the clear liquid is drawn off from below. In another one, used prin- 

 cipally for pastes, the tomatoes are mixed with a large amount of 

 salt and allowed to ferment until the sugars, citric acid, and other 

 easily changed substances have entirely disappeared, and this product 

 is then put into cans without any sterilization. As both of these proc- 

 esses are based primarily on fermentative actions, tomato products 

 prepared in these ways are necessarily composed of a decomposed 

 vegetable product and, hence, such methods of manufacture appear to 

 be indefensible. 



EXAMINATION OF TOMATO PRODUCTS. 



The acid of tomatoes has been called by various authors malic, 

 citric, tartaric, and oxalic. The acid is actually citric acid, as shown 

 by the following: 



(1) Ordinary qualitative tests for oxalic acid on some tomato juice 

 gave negative results; tomato juice to which 0.01 per cent, of oxalic 



