Some Japanese salted greens often contain large quantities of nitrous acid which have already been proved to be derived from nitrate in vegetable juice by some bacteria.
We quantitatively estimated nitrate content (as N
2O
5) in various vegetables by the diphenylamine sulfuric acid reagent and by the xylenol method.
The results are as follows:
The figures are N
2O
5mg in 1, 000ml of pressed juice.
Celery 1, 025, spinach 830, roots of radish 612, burdock 580, leaves of Welsh onion 450, shepherd's purse 430, chinese cabbage 350, lettuce 302, white mush melon 295, carrot 255, leaves of radish 260, asparagus 230, beafsteak plant 217, egg apple 212, cucumber 175. cabbage 160, onion 160, tomato 150 and scallion 145.
When such vegetables are salted in summer, nitrite reaches its maximum amount in 24-29hours and then disappears entirely after 3-4days, while in winter reaching its maximum one in 72hours and then decreases gradually.
View full abstract