蒸馏废液中金属离子对木薯淀粉液化过程的影响及优化

Effect of metal ion in distillery waste on cassava starch lique faction and its optimization

蒸馏废液回用可有效减少酒精生产中的废水排放量,但会导致发酵结束后残糖升高。研究发现,蒸馏废液对液化过程的抑制是造成残糖升高的主要原因。文中考察了蒸馏废液中金属离子对耐高温ɑ-淀粉酶酶活及二级结构(ɑ-螺旋、β-折叠、β-转角及无规则卷曲)的影响。结果表明,在对应浓度下(与蒸馏废液中的浓度一致),Na^+(55.89 mmol/L)和K+(33.27 mmol/L)对淀粉酶酶活没有影响;Al^(3+)(3.85 mmol/L)和Li+(0.98mmol/L)对酶活有轻微抑制;Mg^(2+)(7.24 mmol/L)和Ca^(2+)(3.87 mmol/L)对酶活有促进作用;Fe^(3+)(1.40 mmol/L)使酶活下降19.18%。淀粉酶二级结构中ɑ-螺旋含量下降可能是Fe^(3+)造成酶活下降的原因。蒸馏废液中加入16mmol/L Mg2+可以使液化效果恢复至正常水平,并降低酒精发酵结束后的残糖含量。

Recycling distillery waste in ethanol fermentation can effectively reduce discharge of waste water.However this results in increased residual sugar concentration. It has been found that inhibition of the liquefaction process by distillery waste caused the increased residual sugar concentration. Effects of metal ions in the distillery waste on the activity and secondary structure of α-amylase were studied herein. Results showed that 55. 89 mmol / L Na＋and 33. 27 mmol / L K＋had no effect on the α-amylase activity. 3. 85 mmol / L Al^3＋and 0. 98 mmol / L Li＋had a slight inhibition on α-amylase activity. 7. 24 mmol / L Mg^2＋and 3. 87 mmol / L Ca^2＋could stimulate the α-amylase activity. α-amylase was mainly inhibited by Fe^3＋and the enzyme activity was reduced by 19. 18% with 1. 4mmol / L Fe3 ＋.α-helical decrease caused by Fe^3＋maybe resulted in inhibition of ɑ-amylase activity. Meanwhile,addition of 16 mmol /L Mg^2＋to the distillery waste could promote the liquefaction of starch and decrease the residual sugar concentration.