chapter  7
22 Pages

Fermented Soybean Pastes Miso and Shoyu with Reference to Aroma

ByEtsuko Sugawara

Japanese soy sauce (shoyu) and fermented soybean paste (miso) are manufactured by almost the same fermentation process under a high concentration of salt and with many different microbial activities. Shoyu is indispensable for Japanese cooking, and miso is used as miso soup in Japan everyday. Rice is the principal food for the Japanese, and rice protein has low concentrations of some essential amino acids. It is thus necessary to make up for the nutritional de™ciencies by consuming other plant protein foods, for example, natto, tofu, miso, and shoyu, all of which are soybean products. In Japan, large amounts of miso are consumed in the form of miso soup. Hirayama (1982) pointed out that daily intake of miso soup signi™cantly reduces the standardized mortality rate from gastric cancer. The origin of miso is not clear; however, it is presumed to be the fermented product of a food named hishio that was prepared from soybean, koji (a fermenting agent made from foxtail millet), and salt around eleventh

7.1 Introduction ....................................................................................................225 7.2Aroma Compounds of Miso and Shoyu .........................................................226 7.3Brewing of Miso ............................................................................................. 227 7.4Brewing of Shoyu ...........................................................................................230 7.5Identi™cation of Important Aroma Components That Exist Together

in Miso and Shoyu .......................................................................................... 231 7.6Changes in the Concentration of HEMF during Fermentation ..................... 233 7.7Formation Mechanism of HEMF by Yeast Cultivation in Model Media ......234 7.8 Effects of the Type of Yeast and Growth Conditions on the

Formation of HEMF.......................................................................................238 7.9HEMF Formation Pathway by Yeast in Miso and Shoyu ..............................240