不同品种芥菜发酵过程中亚硝酸盐变化规律的研究

Dynamic Change of Nitrite in Different Mustard Cultivars during Fermentation

在20℃、4%的食盐浓度自然发酵条件下,研究了4种品种芥菜发酵过程中亚硝酸盐的变化规律,并通过分析发酵过程中硝酸盐含量、可溶性糖含量、硝酸还原酶活性和卤水pH值的变化,对亚硝酸盐的变化机制进行了初步探讨。结果表明,发酵过程中不同品种芥菜中的亚硝酸盐变化趋势一致,但品种间亚硝酸盐含量呈现差异:发酵第1d出现亚硝峰,峰值:水东芥菜(36.39mg/kg)>雪菜(6.15 mg/kg)>包心芥菜(5.04 mg/kg)>春芥(4.59 mg/kg)。第2 d亚硝酸盐含量下降,但在第3 d上升并呈现次亚硝峰,此后逐渐下降。发酵芥菜成品中亚硝酸盐均低于1 mg/kg,其中包心芥菜最低。芥菜中硝酸盐积累量及发酵卤水中的硝酸还原酶活性与亚硝峰峰值正相关;芥菜中的可溶性糖对发酵产酸及亚硝峰消失有促进作用。

Fermentation of four mustard cultivars was carried out at 20 ℃ in 4% （m/V） brine. The dynamic change of rtilrite was investigated. Nitrate and soluble sugar in mustards, nitrate reduetase （NR） activity in both brine and plant tissue, as well as pH of brine were observed to study the variation mechanism of nitrite. Results showed that nitrite contents among cultivars displayed the same trend, whereas contents of nitrite had significant difference. The nitrite contents increased to a peak value after the first day of fermentation with sequence of values in different clutivars： Shuidong mustard （36.39 mg/kg）〉 Potherb mustard （6.15 nag＆g） 〉Leaf mustard （5.04 mg/kg） 〉Chun mustard （4.59 mg/kg）. Contents of nitrite decreased but then increased to the second nitrite peak at the third day. A steady decline of nitrite was observed since the second nitrite peak. Less than 1 mg/kg of nitrites was found in the fermented products, whereas the highest nitrite content was found in fermented potherb mustard product. The nitrate accumulation in mustards and the activity of nitrate reductase in brine significantly correlated to the nitrite peak value. In addition, sugar in mustard promoted the lactic acid fermentation and the disappearance of nitrite peak.