Abstract
The deterioration in aroma of miso soup by heating was evaluated by analyzing the change in headspace volatiles by the solid-phase microextraction method. The number of flavor components detected by gas chromatography-olfactometry increased when the miso suspension was heated to 80°C, more than 3 times the number at room temperature. However, about 40% of these volatiles could not be detected after heating at 80°C for 3 min. 3-Methyl-1-butanol, one of the main flavor components of miso soup, was greatly decreased at the initial stage of heating. Methional contributed to the aroma degradation, being newly formed and increased by heating at 80°C. 4-Hydroxy-2(or 5)-ethy1-5(or 2)-methy1-3(2H)-furanone (HEMF), which is an important flavor component of miso soup, was decomposed by heating at 80°C, with 2,3-hexanedione and 3,4-hexanedione being identified as the HEMF degradation products.
