Effects of cutting and drying method (vacuum freezing, catalytic infrared, and hot air drying) on rehydration kinetics and physicochemical characteristics of ginger (Zingiber officinale Roscoe).

Abstract

The purpose of this study was to discuss the effects of cutting methods (transverse cutting [TC] and longitudinal cutting [LC]) and drying methods (vacuum freeze-drying [FD], hot air drying [HD], catalytic infrared drying [CID]) on rehydration kinetics and physical and chemical characteristics of rehydrated ginger. The research results showed that the rehydration rate and equilibrium moisture content increased with an increase in temperature. LC samples had a higher rehydration rate, while TC samples showed higher equilibrium moisture. Peleg model can fit the rehydration curve of the sample well. The highest coefficient of determination (R2 ) was 0.99, while the sum of squares error and lowest chi-square (χ2 ) was close to zero. Compared with fresh samples, the rehydrated ginger slices had lower gingerol content, total phenol content (TPC), total flavonoid content (TFC), and higher antioxidant activity. The different cutting methods had no significant effect on the physical and chemical properties of rehydrated ginger. In conclusion, TC-CID rehydrated products have better retention of gingerol, TPC, TFC, and antioxidant properties, which was similar to the principal component analysis. PRACTICAL APPLICATION: The results of this study show that transverse cutting combined with catalytic infrared drying is a unique processing technology. Due to the short xylem of transverse cutting ginger, the xylem diameter can be restored during rehydration, the balanced water content was high, and the quality of dried ginger can be restored to the greatest extent. This makes food processors competitive in the operation process and provides better services to consumers.