Effect of agricultural waste on nutritional composition of oyster mushroom (Pleurotus ostreatus)

The oyster mushroom (Pleurotus ostreatus) was cultivated on diverse substrates, encompassing wheat straw (T1), paddy straw (T2), groundnut leaves and straw (T3), sugarcane bagasses (T4), cotton stalk (T5), coconut husk (T6), pigeon pea straw (T7), and banana pseudostem (T8). The study comprised of the estimation of proximate composition, antioxidants, and mineral content of the sun-dried mushrooms during the initial two harvests. The average values of nutritional parameters were as follows: moisture (90.93 to 85.18 %), ash (7.62 to 4.86%), carbohydrates (37.57 to 20.10%), crude protein (45.45 to 23.10%), crude fiber (29.08 to 19.29%), crude fat (2.68 to 1.63%), total phenol (14.23 to 9.12 mg/g) and ascorbic acid (11.58 to 8.72 mg/100g). The average mineral content exhibited the trend K>P>Mg>Ca>Zn>Fe>Cu. Upon consideration of average values from both harvests, the groundnut leaves and straw had the highest crude protein (45.45 %), total phenol (14.23 mg/g), ascorbic acid (11.58 mg/100g), phosphorous (0.43 %), iron (7.12 mg/100g) and zinc (12.43 mg/100g). The paddy straw resulted in the highest crude fiber (29.08 %) and crude fat (2.68 %), while the wheat straw resulted in the highest potassium (1.52 %) and calcium (179.65 mg/100g). The various substrates had an impact on nutritional parameters as seen by either an increase or decrease in various parameters which can be reflected in turn by the composition of the substrates itself. In conclusion, groundnut leaves and straw (T3) along with paddy straw (T2) and wheat straw (T1) resulted in significant improvement of nutritional composition compared to other treatments. This study underscores the environmentally friendly utilization of nutrients from agricultural waste for mushroom production.