微波加热对酿酒酵母发糕中果聚糖降解作用的机制研究

Mechanism of the Effect of Microwave Heating on the Degradation of Fructans in Steamed Cakes Prepared with Saccharomyces cerevisiae

摘要:

【目的】探究微波加热对酿酒酵母（Saccharomyces cerevisiae)发糕中果聚糖质量分数的影响，揭示微波加热激活转化酶活性的分子机制。【方法】通过调控微波功率密度（3.40~5.10 W/g）和加热时间（2~5 min）制备发糕，比较微波加热与传统蒸制发糕中果聚糖质量分数的差异；测定微波加热和水浴加热条件下酿酒酵母来源的转化酶活性；结合分子动力学模拟，解析微波场下转化酶与蔗果三糖的相互作用。【结果】微波处理可显著降低酿酒酵母发糕中果聚糖质量分数，当微波功率密度≥4.25 W/g且加热时间>2 min时，果聚糖质量分数降至0.30%以下，远低于传统蒸制组。微波场下转化酶活性显著提高，其与蔗果三糖的平均氢键数由10.6增至14.3，结合自由能由（-44.78±1.81） kJ/mol降至（-55.60±1.90） kJ/mol。【结论】微波加热通过增强转化酶与底物的氢键网络及库仑相互作用提高酶-底物复合物的稳定性，进而提高转化酶活性，促进酿酒酵母发糕中果聚糖的降解。

Abstract:

[Objective]This study aimed to investigate the effect of microwave heating on the fructan mass fraction in steamed cakes prepared with Saccharomyces cerevisiae and elucidate the molecular mechanism of the activation of invertase by microwave.[Method]Steamed cakes were prepared under varying microwave power density (3.40~5.10 W/g) and heating time (2~5 min), and the fructan mass fraction was compared between steamed cakes prepared by microwave heating and conventional steaming. The activity of invertase from Saccharomyces cerevisiae was measured under microwave heating and water bath heating conditions. Molecular dynamics simulations were performed to explore the invertase-kestose interactions under microwave fields.[Result]Microwave treatment significantly reduced fructan mass fraction in steamed cakes prepared with Saccharomyces cerevisiae. At the microwave power density ≥4.25 W/g and heating time >2 min, the fructan mass fraction decreased to below 0.30%, which was much lower than that under conventional steaming. Microwave enhanced the invertase activity, increasing hydrogen bonds between invertase and kestose from 10.6 to 14.3 and lowering binding free energy from (-44.78±1.81) kJ/mol to (-55.60±1.90) kJ/mol.[Conclusion]Microwave heating strengthens hydrogen bonding and coulombic interactions to stabilize enzyme-substrate complexes, thereby enhancing invertase activity and promoting fructan degradation in steamed cakes prepared with Saccharomyces cerevisiae.