Agro-waste substrates on the proximate composition of grey oyster mushroom (Pleurotus ostreatus JACQ.) in Abia-State.

Effect of agro-wastes on Pleurotus ostreatus nutrient and mineral composition was investigated using four substrates; bread fruit (Treculia africana), sterilized sawdust, non- sterilized sawdust and cassava peel. Mushroom grown on bread fruit substrate recorded significantly (p ≤ 0.05) the highest moisture content (14.68 %), followed by non-sterilized sawdust (13.97 %) comparable with cassava peel (13.95 %) and sterilized sawdust with least moisture content (13.54 %). Bread fruit substrate recorded the highest ash level (7.94 %) which was comparable with sterilized cassava peel (7.88 %) followed by non-sterilized sawdust (7.75 %) and sterilized sawdust (6.93 %). Also, bread fruit substrate recorded the highest protein content (22.43 %) followed by sterilized cassava peel (21.13 %), non-sterilized sawdust (20.11 %) and sterilized sawdust (19.15 %). The sterilized sawdust recorded the highest fat (3.82 %) comparable to cassava peel (3.75 %), followed by bread fruit substrate (3.40 %) and non-sterilized sawdust (3.34 %). Cassava peel had the highest Vitamin B1 content (2.11 mg/100 g), followed by non-sterilized sawdust (1.64 mg/100 g), breadfruit (1.28 mg/100g) and sterilized sawdust (1.03 mg/100 g). Sterilized sawdust recorded the highest Vitamin C (0.89 mg/100g) comparable (p ≤ 0.05) with cassava peel (0.87 mg/100 g) and there was no significant (p ≤ 0.05) difference in the Vitamin C content of breadfruit substrate (0.76 mg/100 g) and non-sterilized sawdust (0.70 mg/100 g). Non-sterilized sawdust significantly (p ≤ 0.05) recorded the highest Iron (Fe) content (8.28 mg/100 g), followed by breadfruit substrate (7.20 mg/100 g) comparable with cassava peel (7.16 mg/100 g) and sterilized sawdust (6.17 mg/100 g). Breadfruit substrate had the highest calcium (Ca) content (24.72 mg/100 g), followed by cassava peel (24.48 mg/100 g) that was comparable with sterilized sawdust (24.44 mg/100 g) and then non-sterilized sawdust (24.27 mg/100 g). Breadfruit substrate in addition gave the highest magnesium (Mg) content (21.69 mg/100 g) followed by sterilized sawdust (21.56 mg/100 g), non-sterilized sawdust (20.20 mg/100 g) and sterilized cassava peel that had the least magnesium (Mg) content (19.76 mg/100 g). In general, the highest nutrient and mineral composition were recorded in breadfruit substrate (moisture, ash, crude protein, Ca and Mg), sterilized sawdust (fat), cassava peel (Vitamin B1), sterilized sawdust (Vitamin C), and non-sterilized sawdust (Fe).