Microwave infrared vibrating bed drying of ginger: Drying qualities, microstructure and browning mechanism

In this study, microwave infrared vibrating bed drying (MIVBD) method was used to dry ginger and the key characteristics of the product were determined, in terms of drying characteristics, microstructure, phenolic and flavonoid contents, ascorbic acid (AA), sugar content, and antioxidant properties. The mechanism of sample browning during drying was investigated. The results showed that increased infrared temperature and microwave power increased the drying rate and caused microstructure damage to the samples. At the same time, which caused the degradation of the active ingredients, promoted Maillard reaction between reducing sugar and amino acid, and caused the increase of 5-hydroxymethylfurfural, then the degree of browning increased. The AA reacted with amino acid to also caused browning. Antioxidant activity was significantly affected by AA and phenolics (r > 0.95). The quality and efficiency of drying can be effectively improved by MIVBD, and the browning can be reduced by controlling infrared temperature and microwave power.