Comparative study on enzyme activity, microstructure, drying kinetics, and physicochemical properties of apple slices affected by microwave and steam blanching

Abstract

The influence of microwave blanching (MWB) at different times (30–120 s) on the physicochemical properties, microstructure, and drying characteristics of apple slices, compared to steam blanching (SB) was investigated. Results showed that MWB resulted in greater weight loss and more efficient enzyme inactivation efficiency than SB. The MWB process facilitated the moisture diffusion, resulting in a significant (p < 0.05) reduction in drying time of up to 27.78 % and specific energy consumption of up to 50.00 %. Microstructural observations confirmed that this result stemmed from the development of microporous channels within the cellular tissue structure. The Page model exhibited a higher applicability to the drying of apple slices. Moreover, MWB was more effective than SB in inhibiting browning and retaining phenolic compounds. However, concerning amino acid retention, the dried samples treated with SB for 30 s (21.36 ± 0.83 mg/g DW) showed superior performance compared to dried samples treated with MWB. In addition, molecular docking results suggested that amino acids could form the distinctive flavor of dried apple slices through hydrogen bonding with taste receptors.