36E-9 |
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N. J. DUBOST1, R. B. Beelman, and D. G. Peterson. (1) Food Science Dept., Pennsylvania State Univ., 20 Borland Laboratory, State College, PA 16801 L-Ergothioneine (LE) is a naturally occurring antioxidant that is only available from dietary sources particularly fungi. Currently there is a lack of an adequate assay applicable to plant material to quantify this unique antioxidant. Our objective is to quantify the LE content in Agaricus bisporus, Lentinula edodes, Pleurotus osteratus, Pleurotus eryngii and Grifola frondosa mushrooms by an analytical method utilizing LC-MS. One gram of freeze dried mushroom powder was suspended and well mixed in 20 milliliters (ml) of 70% ethanol which consisted of 10 mM dithiothreitol, 100 μM betaine and 100 μM 1-mercapto-2-methyl imidazole. Four ml of 1.0% ethanolic sodium dodecylsulfate was added and centrifugation was completed. One ml of the supernatant was removed and dried under nitrogen gas. The sample was resuspended in 0.5 ml of water at a neutral pH and filtered prior to injection. Reverse phase HPLC was utilized with separation completed by two C18 columns. The isocratic mobile phase was an aqueous buffer with 3% acetonitrile and 0.1% triethylamine adjusted to a neutral pH at a flow rate of 1 ml per minute. LE was detected by monitoring absorbance at 254 nm with an UV-VIS detector and quantified by comparing the peak height and retention time of the sample to peak heights and retention times obtained from pure standard LE. LC-MS was employed to support our data. LE present in the mushrooms ranged from 0.4-2.0 mg/g dry weight. The common button mushroom contained the least LE. The other mushrooms tested (Lentinula edodes, Pleurotus osteratus, Pleurotus eryngii and Grifola frondosa) all contained a greater amount of LE but there was no significant difference found between them. Our results indicate that mushrooms are an excellent source of LE. With this methodology, researchers can begin to quantify this antioxidant in food sources.
Session 36E, Fruit & Vegetable Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |