Kokumi Taste Active Peptides Modulate Salt and Umami Taste.

Kokumi taste substances exemplified by γ-glutamyl peptides and Maillard Peptides modulate salt and umami tastes. However, the underlying mechanism for their action has not been delineated. Here, we investigated the effects of a kokumi taste active and inactive peptide fraction (500-10,000 Da) isolated from mature (FII(m)) and immature (FII(im)) Ganjang, a typical Korean soy sauce, on salt and umami taste responses in humans and rodents. Only FII(m) (0.1-1.0%) produced a biphasic effect in rat chorda tympani (CT) taste nerve responses to lingual stimulation with 100 mM NaCl + 5 μM benzamil, a specific epithelial Na(+) channel blocker. Both elevated temperature (42 °C) and FII(m) produced synergistic effects on the NaCl + benzamil CT response. At 0.5% FII(m) produced the maximum increase in rat CT response to NaCl + benzamil, and enhanced salt taste intensity in human subjects. At 2.5% FII(m) enhanced rat CT response to glutamate that was equivalent to the enhancement observed with 1 mM IMP. In human subjects, 0.3% FII(m) produced enhancement of umami taste. These results suggest that FII(m) modulates amiloride-insensitive salt taste and umami taste at different concentration ranges in rats and humans.