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Chemical compositions of oyster mushrooms (Pleurotus ostreatus and Pleurotus pulmonarius) under storage

S.G.Jonathan, E.O.Esho, I.A.Ajayi

Effect of storage time on chemical compositions of Pleurotus ostreatus and Pleurotus pulmonarius (two cultivated oyster mushrooms from Nigeria) were investigated. These two edible fungi were analysed for crude protein, crude fibre, crude fat, ash content, moisture content, dry matter and mineral elements (Na, K, P, Ca, Mg, Fe, Cu and Mn)at 0day (fresh samples),35,70,105 and 140 days. The results reflected higher percentage of these nutrients in the fresh fungal samples with P. ostreatus and P. pulmonarius having 31.40 and 28.65% crude protein respectively in their fresh samples. These values however reduced drastically to 25.60 and 24.10 %in P. ostreatus and P. pulmonarius respectively after 140days of storage .Similar trends were observed in the two mushrooms for all other food components except for moisture contents. The best mineral element in the fresh samples of the two mushrooms was magnesiumwith 7.41 mg/g (in P. ostreatus) and 6.91 mg/g (in P. pulmonarius). These values reduced significantly as the storage time increases (P<0.05).Potassium, calcium, phosphorus and sodium were also found at significant quantities in both fresh and stored mushroom samples. Similarly, micro-elements such as Fe, Cu and Mn were detected at appreciable quantities in both fresh and stored fungal samples. The implications of these findings were discussed.