Numerical Simulation of Saccharification Reaction Kinetics in Potato Starch under Intermittent Microwave-Hot Air Treatment

Based on the high starch content characteristic of potatoes, a kinetic model for potato slices was developed to describe the conversion of non-gelatinized starch (NSG) to gelatinized starch (SG) and the subsequent hydrolysis of gelatinized starch into maltose (M) by β-amylase (AE). Numerical simulations were performed using the commercial software COMSOL Multiphysics 6.0. The hydrolysis process of starch after gelatinization under the action of AE was analyzed under two main scenarios: first, under intermittent microwave-convective conditions with the same microwave power density (P _w =3.2W/g) but different Pulse Ratio (PR = 1/5, 1/4, 1/3, 1/2, 1); second, with the same PR (1/2) but different P _w values (1.6, 3.2, 4.8, 6.4, 8.0W/g). The results demonstrated that under intermittent microwave conditions (PR ≠ 1), the Average Saccharification Rate (ASR) increased with rising values of both the specific P _w and the PR. When the PR = 3/4, the ASR values corresponding to P _w values of 3.2W/g, 4.8W/g, and 6.4W/g were 5.62%, 3.30%, and 2.58% higher, respectively, than those obtained at a PR = 1/5 under the same P _w conditions. Conversely, when the specific P _w =1.6W/g, the ASR values for PR values of 1/2, 1/3, and 1/4 were 2.81%, 3.15%, and 3.41% higher, respectively, than the values observed at a higher P _w =8.0 W/g with the corresponding PR values. Compared to PR = 1, intermittent microwave irradiation advanced the initiation and reduced the overall duration of starch gelatinization. Furthermore, the mathematical regression model for the average maltose content of the potato slice samples was established based on the factors 1/PR and P _w .