Mass spectrometry imaging reveals flavor distribution in edible mushrooms

The spatial distribution of molecules and compounds responsible for the flavor profile of edible button mushrooms (Agaricus bisporous) has never been determined. The food industry is interested in knowing the localization of these compounds. Such knowledge would enable extraction of flavor compounds from a particular regions of the mushroom, which is safer for consumption compared to alternatives such as synthetic flavoring agents. The present study utilizes matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI), to determine the spatial distribution of flavor compounds in a mushroom. As MALDI-MSI requires very thin sections, a sample preparation protocol was optimized and sectioning fresh frozen mushrooms at 35 mu m thickness was considered the best method to evaluate the distribution of flavor compounds. Further, the effect of heat on the spatial distribution of flavor compounds was investigated by heating whole mushrooms to 140 celcius prior to sectioning. Heating reduced the water content of the mushroom and thus enabled the generation of even-thinner 17 mu m thick sections. MALDI-MSI measurements performed on underivatized and on-tissue derivatized fresh frozen and heat-treated mushroom sections elucidated the spatial distribution of several flavor-related compounds.