Chemical Composition and Nutritional Value of Mature and Young Fruiting-Bodies of Pleurotus Pulmonarius Produced On Andropogon Gayanus Straw and Khaya Ivorensis Sawdust

Abstract

Pleurotus. Pulmonarius was cultured in the laboratory of the Department of plant Sciences and Biotechnology, Michael Okpara University of Agriculture, Umudike. The mycelium of the mushroom was bulked up on guinea corn grains and was used to produce fruit-bodies on Andropogon gayanus straw and Khaya invorensis sawdust. The Chemical composition and nutritional values of the young and mature fruit-bodies evaluated. The nutrient composition in terms of the crude oil, protein, ash, total carbohydrate content mineral and vitamins contents were analyzed, and these were found out to vary dependent upon the stage of fruit-body development and substrate types. The moisture content was at maximum at immature stage and decreased during further development of the mushroom while the ash and fibre contents showed an opposite trend. The highest ash and fibre contents were obtained from the matured fruit-bodies and the lowest in the young fruitbodies. Similarly the fats and protein contents of the mature fruit-bodies were higher than those of the young fruit-bodies. However the carbohydrate contents of the mushroom fruit-bodies were neither influenced by the substrates nor their stages of development. There was no significant difference between the proximate compositions of the fruit-bodies harvested from Andropogon gayanus straw and those from Khaya invorensis. The fruit-bodies were equally rich in Niacin, Thiamine, Ascorbic acid and Riboflavin. However the concentrations of the vitamins (in mg/100g) were more in the fruit-bodies harvested from A. gayanus straw than those from K. invorensis sawdust. In each case however, matured fruit-bodies had higher contents of the vitamins than young fruit-bodies. The result of the analyses shows that P. pulmonarius fruit-bodies contained minerals (Potassium, Sodium, Magnesium, Phosphorus and Calcium) and bio-active compounds (Alkaloids, Phenol, Tannin, Saponin and Hydrogen cyanide) in varying quantities. and mineral elements (Potassium, Sodium, Magnesium, Phosphorus and Calcium). Andropogon straw produced fruit-bodies with higher Potassium, than those from Khaya sawdust and this mineral occurred more in the matured fruit-bodies than in young ones in each case. The other minerals were low and did not show any defined trend in both the substrate and in the stages of development. Similarly, Alkaloids, contents of both matured and young fruit-bodies and from the two substrates were higher than the rest of the bioactive compounds respectively. The results of the investigation were discussed in relation of the best stage of the fruit-bodies for consumption and best substrate for the cultivation of the mushroom