It is important to learn about changes in both taste and odor perceptions with increasing age, because the taste of foods we encounter in our daily life is strongly affected by their smell. This study discusses the difference in qualitative taste and odor discrimination between the elderly and the young. Tastants and odorants used in this study were presented not as single stimuli but as a taste mixture (sucrose and tartaric acid) and an odor mixture (beta-phenylethyl alcohol and gamma-undecalactone). The results showed that quality discrimination abilities of the elderly subjects for both taste and odor were significantly lower than those of the young subjects, indicating a decline in quality discrimination abilities related to age. Also, a moderate but significant correlation was observed between the taste discrimination ability and the odor discrimination ability. We measured thresholds for single-taste and odor components in mixtures and compared them between the elderly and the young to investigate the cause for these findings.

We tried to detect the human brain activity evoked by beer taste using magnetoencephalography. Subjects did not perceive bitterness and tactile stimulus differences between water and commercial beer, through a small hole of the taste stimulator, but they perceived bitterness for the beer enriched with isohumulones. The increase in the magnetic fields after the stimulation onset was observed for the stimulus of the beer with addition of isohumulones but was not observed for the stimulus of water or commercial beer, supporting the subject's comments. In 76.2% of the all measurements for the beer enriched with isohumulones, the equivalent current dipoles, placed on a subject's 3-dimensional magnetic resonance imaging, were located at the transition between the parietal operculum and the insular cortex with latency at 326.7 Ϯ Ϯ Ϯ Ϯ Ϯ 115.5 ms. These results indicated that the brain activity stimulated by beer bitterness could be detected.