Umami Taste in Japanese Traditional Miso Soup for the Elderly

Abstract

Elderly people often suffer from taste disorder, with subsequent appetite loss. A reduction in umami-taste sensitivity is strongly related to appetite loss. Under these circumstances, how is umami taste considered and applied to foods for the elderly in Japan? In this study, we measured the concentration of L-glutamate (a typical umami amino acid) in 658 different miso soups served in 220 institutions for the elderly in Japan. Miso soup is a popular Japanese savory soup made with soup stock (dashi) and fermented soybean paste (miso), both of which are abundant in umami substances. The concentration of L-glutamate in the miso soups was the highest among the measured amino acids (Av ± SD: 156.3 ± 101.3 mg/100 g) with a very large range (15.7-697 mg/100 g, CV: 64.8%). We also measured the sodium concentration in the same miso soups (Av ± SD: 328.5 ± 70.1 mg/100 g) and found that it is controlled in a narrow range (CV: 21%). We should further investigate whether these concentrations are preferred by the elderly, for the improvement of their appetite and nutritional status.