Effect of different treatments on nitrite level in leafy vegetables during storage

To reduce the risk of contamination of leafy vegetables with nitrite, effects of different treatments and storage time on nitrite levels were analyzed. The Chinese cabbage (Brassica pekinensis) and cabbage (B. oleracea) were used as the test materials, and fried or boiled materials were stored at 4 ℃ with or without bagging, as well as with ensiling. Ensiling were performed for 6, 12, 24 and 48 h, and 40 d, and other treatments were performed for 6,12,24 and 48 h. The results showed that pretreatment had significant effects on the levels of nitrate and nitrite in the Chinese cabbage and cabbage (P<0.05); however, bagging did not exert significant effects on the levels of nitrate and nitrite (P>0.05). After boiling and frying, the nitrite level in the leafy vegetables stored at 4 ℃ for 48 h did not increase significantly. Nitrite level decreased at the beginning of ensiling, increased significantly after 24 h (Chinese cabbage) or 12 h (cabbage), and then decreased (40 d for Chinese cabbage, 48 h for cabbage after storage). The nitrite level in the cabbage ensiled for 40 d, in particular, was lower than that in the original material (P<0.05).