Physicochemical characteristics, antioxidant capacity and thermodynamic properties of purple-fleshed potatos dried by radio frequency energy

The impacts of using radio frequency (RF) energy to dry purple-fleshed potatoes were investigated and compared to infrared radiation (IR) and microwave (MW) drying techniques. The gelatinization rate, color, flavor, morphological, and structural characteristics, thermodynamic properties, as well as antioxidant capacity were examined. The results indicated that the drying time of RF (70 min) and MW (21 min) were shorter than IR (105 min). The gelatinization ratio of MW, RF, and IR were 94.4 ± 2.0, 88.3 ± 1.4, and 64.5 ± 1.1%, respectively. The degree of crystallization of purple-fleshed potato powder decreased with all three drying methods. RF-dried potatoes were able to retain higher polyphenols (loss rate: 4.3%), total anthocyanin (3.7%), and total flavonoid content (35.1%), whereas IR showed the lowest retention. The content of polyphenols also decreased significantly. Furthermore, after RF heating, the scavenging of free radicals was higher compared to MW and IR.