Program

Poster Presentations

Day 2, June 11（Thu.）　　Room P (5F 501+502)

2P-26

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Investigation of the Distribution of the Pungent Compound in Japanese Horseradish by MALDI-MSI

(¹UOsaka, ²S&B Foods, ³UOsaka)
^oRika Fujimoto¹, Kenta Suzuki², Mitsunori Sakata², Takehito Sagawa², Keiko Ito², Shuichi Shimma^1,3

Japanese horseradish is a perennial plant of the Brassicaceae family, valued for its characteristic pungent flavor. This pungency is primarily derived from allyl isothiocyanate, which is generated through myrosinase-catalyzed degradation of the glucosinolate sinigrin upon tissue disruption. Although the enzymatic reaction responsible for pungent compound formation has been well characterized biochemically, the spatial relationship between sinigrin and myrosinase within plant tissues remains poorly understood. To investigate the spatial characteristics associated with pungent compound formation, matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) was applied to visualize the distributions of sinigrin and myrosinase in Japanese horseradish tissues. Because allyl isothiocyanate is highly volatile and difficult to detect directly, its precursor sinigrin and the enzyme myrosinase were analyzed instead. Fresh samples were vacuum-packed, frozen in liquid nitrogen, and sectioned using a cryo-microtome. Sinigrin detection conditions were optimized using standards, and the strongest signal was obtained in negative ion mode with 9-aminoacridine as the matrix. Under optimized conditions, sinigrin was scarcely detected near vascular bundles, suggesting degradation by myrosinase during sectioning. Heat inactivation of myrosinase resulted in uniform sinigrin distribution throughout tissues, indicating enzyme localization near vascular bundles.

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