Influence of different substrates on fruiting bodies yield and antioxidant properties of oyster mushroom

The present study was designed to evealuate the influence of different substrates on the yield and antioxidant properties of oyster mushroom (Pleurotus ostrestus) cultivated in 'bag-logs'. The substrates used in this study were: (1) maize straw, (2) beech sawdust mixed with wheat bran, and (3 and 4) maize straw mixed with spent coffee grounds mixed in a different ratio. Total phenolics, total flavonoids and total antioxidant acitivity of oyster mushroom were determined by the Folin-Ciocalteu method, Aluminium chloride method and Ferric Reducing Antioxidant Power Assay, respectively. The highest fruiting bodies yield of oyster mushroom was obtained from substrate 4 (maize straw mixed with spent coffee grounds in a ratio of 50:50), while the least was from substrate 1 (maize straw). Total phenolic contents ranged from 3.80 mg in oyster mushroom grown on substrate 4 (maize straw mixed with spent coffee grounds in a ratio of 50:50) to 4.85 mg of gallic acid equivalents g-1 dry mass in oyster mushroom form substrate 2 (beech sawdust mixed with wheat bran). Total flavonoid contents were very low in all analysed mushroom extracts. There was no significant difference between total antioxidant activities of oyster mushroom grown on different substrates.