大白菜贮藏过程中硝酸盐和亚硝酸盐含量变化分析

在不同贮藏温度（0、10、20 ℃）、贮藏方式（未包装、0.04 mm PE保鲜袋包装）条件下贮藏大白菜（Brassica rapa pekinensis）16 d后，采用高效液相色谱法测定大白菜中硝酸盐和亚硝酸盐含量的变化。结果表明，在不同贮藏温度和贮藏方式条件下，硝酸盐和亚硝酸盐的含量随着贮藏时间的延长均呈现先增加、后降
低、再上升的趋势，其中硝酸盐的含量在整个贮藏期间，均在低于432 mg/kg的安全食用范围内；亚硝酸盐含量在20 ℃贮藏条件下贮藏7 d即超过了4 mg/kg的安全摄入量，而其他贮藏条件均在安全食用范围内。大白菜中硝酸盐与亚硝酸盐的含量在贮藏过程中随贮藏温度的降低而显著减少，到贮藏末期（16 d时）20 ℃和10 ℃贮藏大白菜中硝酸盐含量分别是0 ℃贮藏的1.2 倍和1.1 倍，亚硝酸盐含量分别是0 ℃贮藏的1.4 倍和1.2 倍。PE保鲜袋包装有助于减少大白菜在中、低温（10、0 ℃）贮藏中硝酸盐与亚硝酸盐的含量，但在高温（20 ℃）贮藏中其含量增加。因此，建议贮藏大白菜时最好采用PE保鲜袋包装和0～10 ℃的贮藏温度，以保证其硝酸盐和亚硝酸盐含量不超标。

Dynamic Changes in Nitrate and Nitrite Contents of Chinese Cabbage during Storage

Changes in nitrate and nitrite contents were determined simultaneously by HPLC in Chinese cabbage (Brassica
pekinensis) stored at different temperatures (0, 10, and 20 ℃) with two packaging modes (not packaged and packaged in
0.04 mm thick PE bags) during a storage period of 16 days. The results showed that the contents of both nitrate and nitrite in
Chinese cabbage were firstly increased, then decreased and further increased at the last storage stage. Nitrate content was in
the safe range (≤ 432 mg/kg) during the whole storage period. The nitrite content in Chinese cabbage stored at 20 ℃ for one
week surpassed the security intake (≤ 4 mg/kg) while that in the Chinese cabbage stored under all other conditions remained
in the safe range. The contents of both nitrate and nitrite in Chinese cabbage were reduced significantly with the decrease of
storage temperature during the storage process. At the end of the storage, the nitrate contents in Chinese cabbage stored at
20 ℃ or 10 ℃ were 1.2 and 1.1 times higher than that in cabbages stored at 0 ℃, respectively, while the nitrite contents
were 1.4 and 1.2 times higher than that of cabbages stored at 0 ℃, respectively. Packaging with PE bags helped reduce
the nitrate and nitrite contents in Chinese cabbage stored at 10 and 0 ℃, but the opposite result was observed at 20 ℃.
Therefore, it is suggested that Chinese cabbage storage should be packaged with PE bags and stored at 0–10 ℃ for
effectively controlling of nitrate and nitrite contents in Chinese cabbage.