Proximate Composition, Mineral Element Profile and Antioxidant Properties of the Edible Kenyan Mushroom, Auricularia polytricha

Abstract

The indigenous Kenyan Auricularia polytricha is a known delicacy to the communities residing around Kakamega forest in Western Kenya. The objective of the present study was to carry out proximate analysis, determine selected mineral element levels and radical scavenging capacity of the fruiting bodies of Auricularia polytricha. Proximate analysis which included determination of total carbohydrates, crude protein, crude fibre, crude fat, ash and moisture contents was done according to the Association of Official Analytical Chemists (AOAC) methods. The minerals (Ca, Mg, Fe, Zn, Mn, Pd, Cd) in the dried mushroom sample were determined using an Atomic Absorption Spectrophotometer (AAS) while Na and K were determined by flame emission photometry. Phosphorus was estimated by spectrophotometric method. The antioxidant activity of the crude mushroom extracts was evaluated by measuring their scavenging capacity on the stable radical, DPPH (2,2- Diphenyl-1-Picrylhydrazyl) using UV-Vi’s spectrophotometer at 517 nm. The mushroom was found to contain 64.53% total carbohydrates, 43.12% crude fibre, 11.67% crude proteins, 4.75% crude fat and 4.69% ash content on dry matter basis. The moisture content of the mushroom was found to be 80.33% of the fresh weight, which is typical of fresh foods and vegetables. A methanol extract of the mushroom exhibited antiradical activity against DPPH in a dose dependent manner with the highest radical scavenging capacity (40.84%) obtained at a concentration 500 µg/mL. For the mineral profile, the variations and concentrations of the essential and trace elements under study decreased in the order K˃Na˃Mg˃Ca˃Fe>P>Zn>Mn. The selected hazardous heavy metals Cd and Pb were not detected in the mushroom sample. Implications of the mineral concentrations on the nutritional value of the mushroom have been highlighted. In conclusion, the obtained results suggest that the mushroom, which has good amounts of the required proximate components, minerals and antiradical constituents, is a potentially healthy, safe and functional food.