FORMATION BY YEAST OF THE HEMF (4-HYDROXY-2(OR 5)-ETHYL-5(OR 2)-METHYL-3(2H)-FURANONE) AROMA COMPONENT IN MISO WITH AGING

Two kinds of miso, one with added precultured yeast and the other without, were compared with respect to the changes in the concentration of HEMF formed and the number of yeast cells in the process of aging. In mise without added yeast, the HEMF concentration increased with the increasing number of existing yeast cells. In miso without yeast aged for 21 days after the mise mash, 0.06 ppm HEMF was detected when the cell number was 2.2 x 10(3) cell/g. In yeast-added mise aged for 7 days after the mise mash, no HEMF was detected, although the number of yeast cells was 1.6 x 10(6) cell/g. In yeast-added mise aged for 14 days after the mise mash, HEMF was first detected. The pH levels of mise without yeast and with added yeast when HEMF was first detected H ere 5.59 and 5.57, respectively. It is suggested that the formation of HEMF in miso containing a high concentration of reducing sugar and salt was related to the growth of yeast and started when the pH level fell to less than 5.6.