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

Abstract

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.

Keywords:

• Purple-fleshed potato
• radio frequency drying
• physicochemical characteristics
• antioxidant capacity

Acknowledgments

We also appreciate the assistance from Prof. Shaojin Wang in Northwest A & F University. And we would like to thank Alison Beamish at the University of British Columbia for her assistance with English language and grammatical editing of the manuscript.

Disclosure statement

The authors state that they have no conflicts of interest.

Additional information

Funding

This work was supported by the National Key R&D Program of China (2017YFD0400900); National Natural Science Foundation of China (No. 3160101414). China Postdoctoral Science Foundation under Grant (No. 2016M602866); Shaanxi Postdoctoral Science Foundation under Grant (No. 2016BHSEDZZ101); Doctoral Scientific Research Starting Foundation of Northwest A & F University under Grant and Fundamental Research Funds for the Central Universities (2452016087).