Effects of Drying Methods on Antioxidant Properties and Phenolic Content in White Button Mushroom

Abstract In order to explore the potential drying process, the effects of different drying methods (sun drying, hot-air drying, microwave-vacuum drying, and freeze drying) on the antioxidant properties and phenolic contents in white button mushroom fruit bodies were investigated. The Folin-Ciocalteu method was used to determine total phenolic content, while 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, reducing power, iron-chelating ability, and hydroxyl radical scavenging activity assays were used to elucidate antioxidant activities. Results indicated that antioxidant properties in dried white button mushroom were affected by the drying methods to different extents, and phenolic contents showed significant differences (p<0.05) among different drying methods. Microwave-vacuum drying possessed the highest antioxidant activity in DPPH radical scavenging, reducing power and iron-chelating ability, respectively; and the content of phenolic compounds was 4.945 mg gallic acid equivalents (GAE) /g dry weight (DW). Sun drying was the worst in antioxidant activity and content of phenolic compounds was 1.964 mg GAE/g DW. Additionally, significantly positive correlation was found between the total phenolic content and antioxidant activity (p<0.01). As far as antioxidant activities are concerned, microwave-vacuum drying is proposed as an appropriate drying technique for white button mushroom.