Evaluation of the nutritive value and metal content of prevalent edible mushrooms in Bangladesh

Mushroom cultivation in Bangladesh has been on the rise, however, their nutrient and heavy metal content is not well investigated. Herein, prevalent cultivars and strains of five mushroom species (Pleurotus ostreatus, Pleurotus sajor-caju, Pleurotus citrinopileatus, Auricularia auricula and Ganoderma lucidum) were analyzed for their nutritional values (total ash, lipid, crude fiber, protein and carbohydrates) as well as metal concentrations using standard methods. This study was conducted at the Laboratory of the Biochemistry Department at Sher-e Bangla Agricultural University, Dhaka, Bangladesh, from January to December 2022. The proximate composition of mushrooms varied from 2.67–11.57%, 2.05-3.81%, 15.52-22.61%, 6.1-12.71% and 46.01-57.85% for total ash, lipid, crude fiber, protein and carbohydrates, respectively. The highest values of Fe, Mn, Zn, P, Ca, Mg, K, S and N were 315.87, 19.14, 267.96, 2.92, 1.07, 0.44, 4.62, 0.78 and 3.06 ìg/g, respectively. Remarkably, the highest amounts of heavy metals, Pb (5.65 ìg/g) and Cd (0.22 ìg/g) were found in Pleurotus citrinopileatus, while Cr (3.22 ìg/g) and Ni (1.65 ìg/g) were found in a variety of Pleurotus ostreatus. The findings revealed that heavy metal concentrations in two mushroom varieties exceeded the maximum permissible limit recommended by WHO/FAO. To the best of our knowledge, this is the first comprehensive analysis comparing the nutritional value and metal content of popular mushroom species of Bangladesh.