Improvement and Characterization of Naturally Occurring Folate Compounds in Fruiting Bodies of Culinary-Medicinal Winter Mushroom, Flammulina velutipes (Agaricomycetes)

Edible mushrooms are among food sources containing natural folate compounds. However, little is known about how the content of folates in edible mushrooms may be improved. This study aimed to enrich Flammulina velutipes with higher levels of folates and to characterize patterns of the bioconversion of folates in the fruiting bodies. A convenient method was developed to treat a lignocellulosic substrate with synthetic folic acid. Folate compounds in the fruiting bodies grown in folic acid-treated substrates were evaluated relative to those in untreated substrates. Reverse phase high-performance liquid chromatography revealed different patterns of changes in levels of unsubstituted and substituted folates. While there was an approximately 15-fold and 8-fold increase in 5-formyl tetrahydrofolate and 5-methyl tetrahydrofolate, respectively, the most inconsistency was seen in the tetrahydrofolate content. There were also differences in the level of folate derivatives between commercial and native F. velutipes mushrooms. Since F. velutipes mushrooms can be consumed raw, the enriched mushrooms can be used as a dietary source to meet adult requirements for the daily uptake of natural folates.