Characterization of the Key Odorants in Pan-Fried White Mushrooms (Agaricus bisporus L.) by Means of Molecular Sensory Science: Comparison with the Raw Mushroom Tissue

Application of aroma extract dilution analysis (AEDA) on the volatile fraction isolated from pan-fried white mushrooms (Agaricus bisporus L.) revealed 40 odor-active compounds in the flavor dilution (FD) factor range of 8–8192, among which the caramel-like smelling 4-hydroxy-2,5-dimethylfuran-3(2H)-one showed the highest FD factor of 8192, followed by 2-propionyl-1-pyrroline (popcorn-like) and 3-hydroxy-4,5-dimethylfuran-2(5H)-one (seasoning-like). A total of 36 compounds are reported for the first time in processed mushrooms, and 25 odorants showing the highest FD factors were then quantitated by stable isotope dilution assays and their odor activity values (OAVs) were calculated as ratio of their concentrations to their odor thresholds. Among them, 3-methylbutanal (malty), 3-(methylthio)propanal (cooked potato), and 2-acetyl-1-pyrroline (popcorn-like) showed the highest OAVs (>100) in the pan-fried mushrooms, followed by 1-octen-3-one, 2-propionyl-1-pyrroline, 4-hydroxy-2,5-dimethylfuran-3(2H)-one, phenylacetaldehyde, 2,3-diethyl-5-methylpyrazine, and 3-hydroxy-4,5-dimethylfuran-2(5H)-one with OAVs >10. An aqueous aroma recombinate containing 13 odorants (OAV > 1) in their actual concentrations in the fried mushrooms showed a good similarity to the original aroma profile. The quantitation of the key odorants in raw mushrooms, identified with high FD factors during the AEDA, revealed that numerous odorants were quantitatively changed by the frying process, but in particular the concentrations of 2-phenylacetaldehyde and 3-methylbutanal were higher by factors of ∼40 and 6, respectively, compared to the amounts in the processed mushrooms. The data suggested an enzymatic formation of both Strecker aldehydes by the cut mushroom tissue. In total, 26 odorants were newly identified in raw mushrooms.