香辛蔬菜苦藠粗提液对亚硝酸盐的清除作用

研究苦藠在不同实验条件下对亚硝酸盐的清除能力。选择苦藠粗提液不同的预热温度、pH 值、用量及反应时间进行单因素试验，并在此基础上进行正交试验，以探明清除效果随反应条件所发生的变化。结果表明：高温预热很必要，在苦藠自然pH 值下清除率可达50% 以上；pH 值对清除率影响极显著，pH2.0、11.0mL 的粗提液，反应10min，清除率达到82.7%。以芥菜为对象，设置①预煮后浸于苦藠粗提液中(模拟烹饪)，7℃冷藏，以去离子水浸泡为对照，观察芥菜中亚硝酸盐的积累；②鲜叶去污染后PE 包装置于40℃条件下(模拟高温贮运环境)，检测叶片亚硝酸盐的变化。贮存达13d 时，两种浸泡液中芥菜亚硝酸盐的积累都较缓慢，苦藠液中芥菜亚硝酸盐含量始终低于对照，提示煮沸、低温、添加苦藠均有抑制亚硝酸盐形成的能力；40℃条件下，前4d 中，亚硝酸盐含量虽略增但均很低，其后亚硝酸盐含量跃增，第6 天时达到356.4mg/kg，2.0mL 苦藠粗提液在第1、6天的清除率分别为21.1% 和5.9%。

Nitrite Scavenging Effect of the Mechanically Prepared Juice from Chinese Onion,a Condiment Vegetable

In the present study, we evaluated the nitrite scavenging effect of the mechanically prepared juice from Chinese onion eaten as a condiment vegetable in China. Single factor experiments were initially carried out to investigate the effects of preheating temperature and amount of the juice and reaction pH and time on its scavenging ratio against nitrite and based on these investigations, orthogonal array design was then used to search for the optimum values of the above reaction conditions maximizing its scavenging ratio against nitrite. The results showed that preheating at high temperature was necessary for scavenging nitrite by the juice. The scavenging ratio of the juice against nitrite was over 50% at natural pH. pH had exceedingly significant effect on this index. The reaction of 11.0 mL of the juice for 10 min at pH 2.0 gave a nitrite scavenging ratio of 82.7%. Furthermore, precooked mustard leaves (as a simulation for cooking) was soaked in the juice or deionized water (as control) and stored at 7 ℃ and the accumulation of nitrite in mustard leaves was observed during storage. After 13 days of storage, a slow accumulation of nitrite was observed for mustard leaves soaked in deionized water or the juice. Mustard leaves soaked in the juice always presented a lower nitrite content than those soaked in deionized water did throughout the entire storage period. Thus, precooking, low temperature and soaking in the juice all had the ability to suppress the formation of nitrite. Meanwhile, the fresh leaves of mustard were cleaned and packaged in polyethylene bags and stored at 40 ℃ (as a simulation for high-temperature storage and transportation environment) and the nitrite content change of mustard leaves was examined during storage. It was found that the nitrite content in mustard leaves slightly increase in the first days of storage at 40 ℃, followed by a steep increase and reached 356.4 mg/kg on the sixth day and that 2.0 mL of the juice gave nitrite scavenging ratios of 21.1% on the first day and 5.9% on the sixth day.