Proximate Composition, Essential Heavy Metal Concentrations and Nutrient Density of the Mycelium and Fruiting Bodies of Organically Cultivated Pleurotus ostreatus
Samuel C. Onuoha
Department of Biochemistry, Faculty of Science, University of Port Harcourt Choba, Rivers State, Nigeria.
Prince N. Okoroh *
Department of Biochemistry, College of Natural and Applied Sciences, Gregory University, Uturu, P.M.B. 1012, Abia State, Nigeria.
Ruth A. Tom-Quinn
Department of Biochemistry, Faculty of Science, University of Port Harcourt Choba, Rivers State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Proximate composition, essential heavy metal concentration of fruiting bodies (POFB) and mycelium (POMY) of Pleurotus ostreatus were conducted using standard methods. Moisture content was higher (9.79%) in POFB than in POMY (8.76%) on dry weight basis. Ash was higher in POFB(6.25%) than in POMY(3.25%).POFB presented higher crude protein value (24.66%) than POMY (21.17%). Crude fat values were low in both samples(POFB:0.28%; POMY:0.46) respectively. Fiber was higher in the mycelium (14.72%) than in the fruiting bodies (12.90%). The carbohydrate content of the mycelium was 51.93% while the value of carbohydrate in the fruiting bodies was 46.10%. POFB indicated energy value of 285.60Kcal/100g and the value in POMY was 296.57Kcal/100g. Iron, copper, manganese and chromium presented higher values in POFB than in POMY but zinc indicated higher level in POMY than in POFB. The %DV highlighted in the study showed that the fruiting bodies and mycelium of organically cultivated P. ostreatus are rich in protein, fiber, carbohydrate, copper and iron. The nutrient density (ND) results revealed that POFB and POMY samples are nutritionally dense in fiber, copper and iron based on the World Health Food Rating System. The results showed that POFB and POMY obtained by organic cultivation possess high nutritional profile, suggesting that people may use them in food and medicinal formulations.
Keywords: Proximate composition, essential heavy metals, percentage daily value, nutrient density, Fruiting bodies, mycelium, Pleurotus ostreatus.