Mixed liquid seasoning enhanced conditioned flavor learning induced by Japanese pepper in humans and mice.

Japanese pepper (Xanthoxyum piperitum DC.) is often used for the noodle e.t.c, and thought to influence on the palatability of the Japanese dish. However, it was guessed that it was a flavor preferred innately because of its peculiar smell and pungency as well as hot pepper¬. We hypothesized that a preferable flavor of Mixed liquid seasonings (MLS) of soy sauce, bonito broth, sugar and so on affects on the palatability of Japanese pepper flavor. MLS has umami, sweet and salty taste and soy sauce and bonito broth aroma. In this study, we examined whether the MLS could affect the palatability of Japanese pepper by humans (experiment 1) and mice (experiment 2). In the experiment 1, using young subjects, 13 days experiences every before lunch of 30 g Japanese pepper extract + MLS had more tendency of enhancing the palatability Japanese pepper flavor than the experience of Japanese pepper extract only. In the experiment 2, the preference score for Japanese pepper extract of mice which experiences 24 hr two-bottle preference test between Japanese pepper extract + MLS vs. water for 6 days was significantly higher than that of mice which experiences 24 hr two-bottle preference test between Japanese pepper extract vs. water. These results suggest that MLS enhanced palatability of aversive flavor such as pungency of the Japanese pepper in young humans and mice.