Change in Aroma Components of Miso with Aging

Abstract

Aroma concentrates were prepared from rice mold (kome kouji), cooked soybeans and miso at different stage of aging by a method with a porous polymer column. They were analyzed by GC and GC-MS. HEMF (4-hydroxy-2(or 5)-ethyl-5(or 2)-methyl-3(2H)-furanone) contributing to the sweet aroma of miso was not identified in rice mold, cooked soybeans and miso immediately after miso mash. HEMF was identified in miso aged for 30 days after miso mash, and increased gradually with aging. Maltol and HDMF (4-hydroxy2, 5-dimethyl-3 (2H)-furanone) with sweet aroma were identified in cooked soybeans, and did not increased during aging. HEMF was considered to be made by yeast, and maltol and HDMF were considered to be generated by amino-carbonyl reaction in cooked soybeans. The aroma compounds remarkably increased with aging of miso were 4 aliphatic alcohols, 5 aromatics, 5 aliphatic ethyl esters and 3 others (methionol, 5-methyl-2-furfural and HEMF). They were considered to be responsible for the formation of miso-like aroma during aging.