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

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.