咀嚼时间对蔬菜中硝酸盐和亚硝酸盐含量变化的影响研究

Study on the effects of chewing time on the changes of nitrate and nitrite content in vegetables

中文关键词:  咀嚼时间  蔬菜  硝酸盐  亚硝酸盐

英文关键词:chewing time  vegetable  nitrate  nitrite

中文摘要:

      目的 以蔬菜(中青、芽白秧、生菜、油麦菜和包菜)为原料，探讨咀嚼时间对蔬菜所含硝酸盐和亚硝酸盐含量变化的影响。方法 采用超声提取技术提取经志愿者咀嚼不同时间后各种蔬菜中的硝酸盐及亚硝酸盐，以盐酸萘乙二胺为显色剂，采用酶标仪测定两者的含量。结果 咀嚼后的中青、芽白秧、生菜和油麦菜与未咀嚼相比硝酸盐含量显著升高(P<0.05)，达到最高值分别是咀嚼20、5、5和10 s，而包菜的硝酸盐含量无显著性变化；咀嚼后蔬菜的亚硝酸盐含量均显著升高(P<0.05)，不同蔬菜的亚硝酸盐含量达到最高值的咀嚼时间不同，其中中青和生菜的亚硝酸盐含量变化均呈先上升后下降的趋势，分别在20 s [(4.67±0.89) μg/kg]和15 s [(3.63±0.44) μg/kg]达到最高；芽白秧的亚硝酸盐含量则是先上升后下降又上升，在10 s达到最高(4.09±0.57) μg/kg；油麦菜的亚硝酸盐含量在0~20 s不断升高到(6.42±0.70) μg/kg，在10~25 s过程中无显著性变化；包菜的亚硝酸盐含量则是不断上升，在25 s达到最高[(3.48±0.48) μg/kg]。结论 蔬菜因品种、种植条件及营养成分不同，其硝酸盐及亚硝酸盐含量皆不同，各自达到最高值的咀嚼时间也不尽相同，为了减少因摄入亚硝酸盐所带来的健康风险，建议烹饪手法采用焯水或水煮的蔬菜并不食用蔬菜汤，咀嚼方式上细嚼慢咽，咀嚼时间至少为10 s。

英文摘要:

      Objective To explore the effects of chewing time on the changes of nitrate and nitrite content in vegetables, using vegetables (green vegetable, white sprout, lettuce, romaine and cabbage) as raw materials. Methods The nitrate and nitrite were extracted from vegetables chewed by volunteers in different time by ultrasonic extraction, and their content was determined by microplate reader with naphthalene ethylenediamine hydrochloride as color reagent. Results The results showed that the contents of nitrate in chewed green vegetable, white sprout, lettuce and romaine were significantly increased compared with that in unchewed vegetables (P<0.05) and the highest content of nitrate in chewed vegetables was 20, 5, 5 and 10 s, respectively, while there was no significant change in cabbage. After chewing, the content of nitrite in vegetables was significantly increased (P<0.05) and the chewing time of the maximum value of nitrite in different vegetables was different, among which, the content of nitrite in green vegetables and lettuce was firstly increased and then decreased. The maximum values were reached at 20 s [(4.67±0.89) μg/kg] and 15 s [(3.63±0.44) μg/kg], respectively. The content of nitrite in white sprout increased first, then decreased and then increased, and reached the maximum value at 10 s (4.09±0.57) μg/kg. The nitrite content of lettuce continued to increase to (6.42±0.70) μg/kg from 0 to 20 s, but there was no significant change during 10-25 s. The content of nitrite in cabbage increased continuously and reached the maximum at 25 s [(3.48±0.48) μg/kg]. Conclusion Due to the differences in varieties, growing conditions and nutrient composition of vegetables, the nitrate and nitrite content of vegetables is different, and the chewing time to reach the maximum value for each is also varies. In order to reduce the health risks caused by nitrire intake, it is suggested to cook vegetables by blanching or boiling in water and avoid consuming the vegetable soup. Chew slowly and carefully at least 10 s.