Potential utilization of paddy straw and coconut coir for the cultivation of Pleurotus eous: effects on nutritional composition and antioxidant capacity

Abstract

Oyster mushrooms (Pleurotus species), which are valued for their medicinal and nutritional properties, are the predominantly cultivated mushroom variety in Sri Lanka. The most commonly used substrate to cultivate Pleurotus species in Sri Lanka is sawdust. However, due to the availability of many other agricultural wastes in Sri Lanka, the aim of this study was to determine which substrate from paddy straw (PS), coconut coir (CC), and combinations of PS and CC in the ratios of 50 PS:50 CC, 75 PS:25 CC, and 25 PS:75 CC would be the best to grow Pleurotus eous. The weight of each mushroom harvested was measured to determine the highest yield. Lowry and phenol-sulphuric assays were carried out to determine the total protein and total carbohydrate content respectively. DPPH and phophomolybdenum assays were used to analyse the antioxidant activity. The total phenolic content was determined using the Folin-Ciocalteu method. All mushrooms tested positive for qualitative tests of terpenoids, steroids, saponins and polyphenols. 100% PS produced mushrooms with the highest yield (34.72 ± 5.23 g). 50 PS:50 CC produced mushrooms with a significantly high total protein content (5.28 ± 0.24 g/100 g) and total carbohydrate content (31.12 ± 5.64 g/100 g). They also had a high total antioxidant capacity (4.51 ± 0.07 mg AAE/g) and total phenolic content (5.45 ± 0.34 mg GAE/g). Therefore, to cultivate Pleurotus eous, the 50 PS:50 CC combination can be utilized. Based on the mushroom yield, 100% PS can also be recommended for cultivation of Pleurotus eous.