Correlations of cap diameter (pileus width), stipe length and biological efficiency of Pleurotus ostreatus (Ex.Fr.) Kummer cultivated on gamma‑irradiated and steam‑sterilized composted sawdust as an index of quality for pricing

Abstract

Background: Consumption patterns of mushrooms have increased in Ghana recently owing to its acknowledgement as a functional food. Different mushroom cultivation methods and substrate types have been linked to the quality of mushrooms produced, thereby affecting its pricing. Methods: A comparative regression analysis was carried out to assess the correlation of stipe lengths, cap diameters and biological efficiencies of mushroom fruit bodies of Pleurotus ostreatus cultivated on steam-sterilized and gammairradiated sawdust after exposure to ionizing radiations of doses 0, 5, 10, 15, 20, 24 and 32 kGy from a 60CO source (SL 515, Hungary) at a dose rate of 1.7 kGy/h. Steam sterilization of composted substrates was also done at a temperature of 100–105 °C for 2 h. Results: Cap diameters of the mushrooms ranged 41–71.5 and 0–73 mm for gamma-irradiated samples depending on dose and steam-sterilized composted sawdust, respectively. Stipe lengths ranged between 4.4–61 and 0–58.1 for gamma-irradiated samples depending on dose and steam-treated substrates, respectively. Total yields of P. ostreatus grown on the gamma irradiation-treated composted sawdust ranged between 8.8 and 1517 g/kg, while mushrooms from steam sterilized recorded 0–1642 g/kg. Biological efficiencies of mushrooms grown on irradiated sawdust ranged 3–93.3%, while steamed sawdust ranged 0–97%. Good linear correlations were established between the cap diameter and biological efficiency (r2 = 0.70), stipe length and biological efficiency (r2 = 0.91) for mushrooms cultivated on gamma-irradiated sawdust. Similarly, good correlations were established between cap diameter and biological efficiency (r2 = 0.89) stipe length and biological efficiency (r2 = 0.95) for mushrooms cultivated on steam-sterilized sawdust. Conclusion: These correlations provide the possibility to use only the cap diameter and stipe lengths to predict their biological efficiency and also use this parameter for grading and pricing of mushrooms earmarked for the consumer market