Soluble and insoluble oxalate content of mushrooms

Six different cultivars of edible fungi were bought from a local supermarket in Uppsala, Sweden and three different cultivars of wild growing fungi were harvested from the forest adjoining the city. The edible portions of the raw fungi were then analysed for total and soluble oxalate content. A portion of each fungi was then cooked by first boiling in a small amount of water followed by frying in a small amount of butter. The total oxalate content of the raw, commercially grown mushrooms ranged from 58.9 to 104.1 mg/100 g DM while the values for the total oxalate content of the cooked mushrooms ranged from 48.9 to 124.6 mg/100 g DM. Apart from cultivars ostronskivling and piopino the cultivated mushrooms contained mostly insoluble oxalates. Mushrooms harvested from the forest contained only soluble oxalate with the levels ranging from 29.3 to 40.2 mg/100 g DM in the raw tissue. Cooking marginally lowered the soluble oxalate content of these mushrooms. The levels of soluble and insoluble oxalates of all the mushrooms analysed were low compared to other common oxalate-containing vegetables.