Nitrate and nitrite levels in fresh and frozen broccoli. Effect of freezing and cooking

Nitrite and nitrate levels in broccolis coming from different cultures from the south of Navarra (Spain) were analyzed. Fresh products had only traces of nitrites and low levels of nitrates (48–97 ppm KNO3). Industrial freezing gave rise to an increase in the nitrate levels (127–232 ppm KNO3), probably as a consequence of high levels in the processing water. Cooking decreased nitrate levels (between 22 and 79%), there being no differences in the levels of reduction between fresh and frozen vegetables. Nitrite levels were scarcely affected either by freezing or by cooking.