Microwave assisted extraction of chitosan from Agaricus bisporus: techno-functional and microstructural properties

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is primarily derived from chitin. The present research was conducted to generate and analyze chitosan derived from white button mushroom waste (Agaricus bisporus) using microwave assisted extraction. Dried mushroom waste powder was demineralized in diluted acid using 3 M HCl in 1:10 w/v at 540 W for 8 min and deproteinated at 180 W using 10% NaOH in 1:10 w/v for 8 min to remove proteins and lipids. The extracted chitin was deacetylated using 50% NaOH in 1:20 w/v at 360 W to convert it into chitosan. Chitin from the aforesaid process was deacetylated in concentrated alkaline medium at 360 W for 8 min to yield chitosan by converting acetyl groups to -NH₂ groups. The pH and solubility of fresh chitosan were 7.5 and 75%, respectively. Extracted chitosan had maximum 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity of 53.97% and reducing power of 3.58. The microwave irradiation method produced chitosan having degree of deacetylation of 79.94% and crystallinity index of 1.09. The spectra bands confirmed existence of NH₂, OH, CO, CH, and CN functional groups. The X-ray diffraction analysis of the chitosan sample discovered distinct peaks at 2θ values between 10 and 20 °, indicating its semi-crystalline nature.