ESSENTIAL MINERAL AND TOXIC ELEMENTS IN OYSTER MUSHROOM (Pleurotus florida) CULTIVATED ON WATER HYACINTH AND RICE STRAW

摘要

The present study investigated the concentration of three mineral elements (Fe, Zn, Cu) and three toxic elements (Pb, Cd, As) in the cultivation substrate (1:1 mixture of water hyacinth and rice straw) as well as in the cultivated oyster mushrooms Pleurotus florida grown on this substrate. The mean concentrations (mg kg-1 dry weight) obtained for Fe, Zn, Cu, Pb, Cd and As in the mushrooms were 172, 52.3, 10.5, 2.3, 0.95 and 0.7 whereas in the cultivation substrate were 201.5, 56.5, 11.9, 7.2, 2.7 and 2.4 respectively. The contents of Fe, Zn and Cu minerals are in consonance with the reports in literature. Pb and Cd contents are however slightly higher than some of the reports in literature but are within the of recommended safe dietary intake limits established by FAO/WHO expert committee. The coefficient of accumulation of these elements in the mushroom were also calculated by comparing with their concentration in the cultivation substrate and was found in the order of Zn ? Cu ? Fe ? Cd ? Pb ? As indicating P.florida as good accumulator of the minerals. In terms of nutritional aspects, taking into account the recommended dietary allowances or provisional tolerable weekly intake recommended by FAO/WHO, optimum dietary intake of average 100 g day-1 fresh mushroom of P.florida grown on water hyacinth and rice straw is beneficial for health and poses no toxicological risk.