Wasabi (Wasabia japonica) is a Japanese spice of the Brassicaceae family. The underground root of wasabi is grated into a pungent paste and eaten as a condiment with Japanese food such as sashimi, sushi, and soba. With the spreading popularity of sushi in other countries in recent years, the demand for wasabi has surged. Wasabi is strongly fragrant just after grating. The aroma of freshly grated wasabi is not only pungent but also sweet, fruity, green and creamy. In this study we investigated wasabi aroma concentrate by aroma extract dilution analysis. Ten odorants were detected as odor-active compounds at the highest flavor dilution factors of 256 and 1024: 3-methyl-2-butene-1-thiol, allyl isothiocyanate, (Z)-1,5-octadien-3-one, 2-isopropyl-3-methoxypyrazine, 4-pentenyl isothiocyanate, 5-hexenyl isothiocyanate, 3-methyl-2,4-nonanedione, cis-3-methyl-4-decanolide, 6-(methylthio)hexyl isothiocyanate, vanillin. Two of these compounds, (Z)-1,5-octadien-3-one and cis-3-methyl-4-decanolide, were identified in wasabi for the first time. cis-3-Methyl-4-decanolide has only been identified in orchid and no reports describe its identification in foods or the determination of its absolute configuration in nature. To determine the absolute stereochemistry of cis-3-methyl-4-decanolide in wasabi, we synthesized the stereoisomers of 3-methyl-4-decanolide from optically active ?-decalactone. Finally the absolute configuration of cis-3-methyl-4-decanolide was determined as (3R,4R)-3-methyl-4-decanolide by matching the retention time and odour qualities in chiral GC-MS. (3R,4R)-3-Methyl-4-decanolide has a unique odour (peach-like, fruity, creamy, celery-like) compared with the other stereoisomers. To our knowledge, this is the first time that (3R,4R)-3-methyl-4-decanolide has been found in nature.

Determination of the absolute configuration of a novel odour-active lactone, <i>cis</i>-3-methyl-4-decanolide, in wasabi (<i>Wasabia japonica</i>)

248th National Meeting (2014)

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Determination of the absolute configuration of a novel odour-active lactone, cis-3-methyl-4-decanolide, in wasabi (Wasabia japonica)