Chitin from Agaricus bisporus: Extraction and characterization.

Chitin was isolated from three main fruit body parts of the Agaricus bisporus mushroom, i.e. pileus, stipes and gills. Chitin was extracted by alkaline treatment of A. bisporus fruit body parts in 1 M NaOH at 80 °C for 2 h.The lyophilized fruit bodies were examined by SEM and exhibited a porous structure that is favorable to polysaccharide extraction. A mild extraction method was adopted to limit the degradation of chitin. The highest extraction yield of chitin was obtained for stipes (7.4% of dry weight). For pileus and gills, yields of chitin were 6.4% and 5.9%, respectively. Chitin extracted from stipes was characterized by thermal analysis, X-ray diffraction, infrared spectroscopy and solid-state 13C NMR. Results showed that the extracted chitin was in the alpha form, with a 63% crystalline index (CrI) and a degree of N-acetylation (DA) of 70%. The presence of proteins and glucans were not observed in the extracted chitin.