烘烤过程中变黄条件对烤烟淀粉代谢的影响

Effect of yellowing conditions on starch metabolism during curing process of tobacco leaf

【目的】探讨烘烤过程中变黄条件对烤烟淀粉代谢的影响。【方法】采用河南农业大学设计制造的电热式温、湿度自控烤烟箱对供试烟叶进行烘烤，设置不同的变黄温度、变黄时间和凋萎时间，研究烘烤过程中变黄条件对烤烟淀粉代谢的影响。【结果】随着烘烤的进行，淀粉酶活性迅速升高，变黄时间延长比正常烘烤处理淀粉酶活性达到高峰的时间推迟了12h，且烤后烟叶淀粉含量低于正常烘烤处理；较高的变黄温度能促使烟叶中的淀粉在烘烤前期快速降解，但后期淀粉降解停滞的时间较早，最终淀粉含量较高；在42℃延长凋萎时间，烤后烟叶淀粉残留量低。淀粉同工酶电泳胶板上明显可见有3条酶带，分别为α-淀粉酶、β-淀粉酶、R-淀粉酶，其中β-淀粉酶活性最高。电泳图谱显示，各同工酶活性0h时没有差异，24h时高温处理的活性稍高于低温，36h时高温变黄比低温变黄酶活性稍低。【结论】烘烤过程中在35～38℃变黄，并在烟叶变黄后延长12h和在42℃条件下凋萎12h，有利于淀粉降解和烟叶品质改善。

[Objective] The effect of yellowing condition on starch metabolism during curing process of tobacco leaf was studied. [Method] The electric-heated flue-curing barn designed and made by Henan Agriculture University was used by setting different yellowing time, wilting time and yellowing temperature to study the effect of yellowing condition on starch metabolism during curing process. [Result] The activity of amylase increased with the proceeding of curing. The time of the amylase activity to reach a peak of the lengthening of yellowing time treatment was postponed 12 h than normal curing treatment,and the starch content after curing was lower than normal curing. A higher yellowing temperature could impel the toabacco leaf starch degraded completely in the earlier curing stage, but in the later stage the residence time that the starch degraded was earlier, the starch content was higher in the final. Residue starch content was low after 42℃ wilting curing. There were three amylase-isoenzyme bands in electrophoresis plate, α-AMY, β- AMY and R-AMY, and the β-AMY activity was the highest. The electrophoretogram showed that there was no significant difference at 0 h, high temperature enzyme activity treatment was higher than that in low temperature at 24 h,but lower at 36 h. [Conclusion] The low temperature yellowing（35-38℃ yellowing） prolonged yellowing time（prolonger 12h after 35-38℃ yellowing） and prolonged wilting time（42℃ wilting 24 h） during the curing process, which was beneficial to starch degraded and tobacco quality improvement.