蚕豆纳豆发酵工艺优化及其酶学性质

为开发新型蚕豆产品,提高蚕豆附加值研究以蚕豆为原料,通过单因素实验和正交试验优化出蚕豆纳豆的最佳工艺,并对发酵得到的纳豆激酶进行酶学性质研究。结果表明,最佳工艺条件为:蚕豆浸泡48 h,常压蒸煮20 min,接种量为6%,40 ℃下发酵72 h,此时,纳豆激酶活力值最高为(4860.13±470.02) U·g-1,感官评分为(95.67±0.71)分。酶学性质结果表明,该酶在25~40 ℃具有较好的热稳定性;在pH6~9范围内较为稳定,保持相对酶活89.05%以上;Mg2+和Ca2+对纳豆激酶活性具有促进作用,Cu2+、Fe3+抑制作用明显,Zn2+无明显作用。本研究为蚕豆产品的开发及蚕豆纳豆的产业化生产提供参考。

Optimization of Fermentation Process of Natto by Broad Bean and Its Enzymatic Properties

In order to develop new broad bean products and increase the added value of broad bean,this study was based on broad bean as main material.The single-factor experiment and orthogonal experiment were used to optimize the best process of natto by broad bean and then the enzymatic properties of nattokinase were studied.The results showed that the optimal process conditions were as follows: The broad bean were soaked in 48 h and steamed under atmospheric pressure for 20 min,the inoculation of 6% and fermented at 40 ℃ for 72 h.Under these conditions,the enzyme activity reached (4860.13 ± 470.02) U·g-1,and the sensory score was (95.67 ± 0.71) points.Enzymatic properties analysis showed that the nattokinase had a better thermal stability at 25 ℃ to 40 ℃.Meanwhile,the nattokinase had good stability at a pH range from 6 to 9,and the relative enzyme activity was kept over 89.05%.The metal ions of Mg2+ and Ca2+ had an effect on promoting the activity of nattokinase,and the metal ions of Cu2+ and Fe3+ had an obvious effect on inhibiting nattokinase. However,the metal ions of Zn2+ had no obvious effect.This study could provide a reference for the development of broad bean products and the industrial production of broad bean natto.