Abstract
An extract from tomato leaves and stalks, usually known to be rich in“matural”nitrate, was added to the tomato juice, and the juice was packed in plain cans. The whole procedure for canning is described in Table I.
Figs. 1 and 2 show the effect of the“natural”nitrate together with that of the initial pH of the juice on the nitrate-accelerated detinning. The lower was the pH, the faster the occurring of the abnormal detinning, accompanied by a rapid decrease of nitrate. The pH affected the nitrate-induced detinning as well as the“normal”detinning. (Figs. 3, 4)
The dependence of the velocity of detinning on the initial concentration of nitrate indicates that the“natural”nitrate, as well as the added inorganic nitrate, plays the main role on the abnormal detinning in the canned tomato juice (Table II). The relation between pH and the detinning was further confirmed (Fig. 4, Table V). From the reverse proportionality of the detinning to pH, where steeper curves were obtained when the initial pH was lower (Fig. 3), it was concluded that the nitrate-induced detinning proceeded in such a manner that the acidity of the juice cooperated with nitrate.
It was suggested that juices used for packing must not contain more than 3 ppm of nitrate-nitrogen.
