New Method Shows Mushrooms A Top Source For One Antioxidant

The researchers found that white button mushrooms, the mostcommonly consumed kind in the U.S., have about 12 times more of theantioxidant than wheat germ and 4 times more than chicken liver, theprevious top-rated ergothioneine sources based on available data. Untilthe Penn State researchers developed their testing approach, known asan assay, there was no method employing the most sensitive moderninstrumentation and analytical techniques to quantify the amount ofergothioneine in fungi. The researchers say that their assay can beused for other plants, too, not just mushrooms.

Joy Dubost, doctoral candidate in food science, who conducted thestudy, says, "Numerous studies have shown that consuming fruits andvegetables which are high in antioxidants may reduce the risk ofdeveloping chronic diseases. Ergothioneine, a unique metaboliteproduced by fungi, has been shown to have strong antioxidant propertiesand to provide cellular protection within the human body." Dubostdetailed the new assay and the amounts of ergothioneine in the mostcommon and exotic mushrooms typically available in U.S. food stores ina paper presented today (Aug. 31) at the 230th American ChemicalSociety meeting in Washington, D. C. Her paper is Identification andQuantification of Ergothioneine in Cultivated Mushrooms by LiquidChromatography-Mass Spectroscopy. Her co-authors are Dr. Robert B.Beelman, professor of food science; Dr. Devin G. Peterson, assistantprofessor of food science, and Dr. Daniel J. Royse, professor of plantpathology.

The Penn State researchers found that among the most commonly consumedmushrooms, portabellas and criminis have the most ergothioneine,followed closely by the white buttons. A standard 3-ounce USDA servingof these mushrooms, about the amount you'd put on a cheese steak ormushroom-topped burger, supplies up to 5 milligrams.

The exotic mushrooms have even more ergothioneine. The same standardserving size of shiitake, oyster, king oyster or maitake (hen of thewoods) can contain up to 13mg in a 3-ounce serving or about 40 times asmuch as wheat germ.

Dubost notes that the levels of ergothioneine do not decrease when the mushrooms are cooked.

In developing their new assay, the researchers adapted an assay used toquantify the amount of ergothioneine in bovine ocular tissue. They usedhigh performance liquid chromatography (HPLC), a UV-VIS detector andmass spectroscopy, instruments normally used in analytical chemistry.

The Penn State Experiment Station and Mushroom Endowment Fund supportedthe study. The Mushroom Council and NutriCore Northeast are supportingthe Penn State's team's continuing research in this area.