THE IMPORTANCE OF THE FURANONES HDMF AND HEMF IN THE FLAVOR PROFILE OF JAPANESE BARLEY MISO AND THEIR PRODUCTION DURING FERMENTATION

All 13 samples of Japanese barley mise accepted for the Kumamoto Prefe cture Mise Competition of 1995 were assessed by tasting and by GC anal ysis using FID, SIM and olfactometric detection. Forty three compounds were separated by GC, of which 15 had a detectable aroma. Considerati on of the chemical and sensory analyses of this latter group showed th at only the two furanones, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF ) and 4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone (HEMF), co rrelated significantly with the quality of mise flavour (P < 0.05). Ex perimental fermentations of salted barley koji and full barley mise ma sh with Zygosaccharomyces rouxii resulted in alcoholic fermentation in all cases investigated. In contrast, production of the three furanone s, HMMF (4-hydroxy-5-monomethyl-3(2H)-furanone), HDMF and HEMF, was ve ry sensitive to the conditions used. Negligible amounts were found in the absence of soy beans and the highest levels occurred when the full mash was incubated at 37 degrees C for 14 days before inoculation of the yeast. When pre-incubation was carried out, the concentration of H MMF was maximal at the end of mashing and declined during fermentation whilst the amount of both HEMF and HDMF increased. The time courses w ere consistent with synthesis of HEMF, and then HDMF, by the yeast fro m HMMF. (C) 1998 Society of Chemical Industry.