硫化メチルの濃度差における臭気質変化に関する研究

摘要

本研究では低濃度，高濃度で臭気質が変化する物質である硫化メチルを対象とし，臭気質変化の起こる濃度を求め，その濃度を基点としてどのように臭気質が変化するか，臭気質の特徴を明らかにすることを目的とした.濃度差により臭気質が変化する現象は嗅覚受容レベルで起こるため，個人の嗅覚閾値が寄与することが推測される.本研究では被検者10名に対し，三点比較式臭袋法を用いて個人の嗅覚閾値を測定し，臭気強度，快不快度の傾向を明らかにした.また，25名に対し，官能試験を行い，臭気質が変化する濃度および臭気質の特徴について明らかにした.得られた結果を以下に示す.1) 硫化メチルの個人の嗅覚閾値に100倍の差がみられた.2) 臭気強度は，におい物質濃度よりも，臭気指数との相関が高く，臭気質の検討には，感覚量である臭気濃度および臭気指数を用いる必要があることを示した.3) 嗅覚閾値から80倍の濃度で臭気質の変化を感じ，100倍の濃度で明確にうっとうしさ，鋭さが上昇することが明らかとなった.%The present study examined dimethyl sulfide, a substance with an odor quality that varies at high and low concentrations. The concentration at which the change in odor quality occurred was shown and changes in odor quality and characteristics of odor quality were clarified using this concentration as a base point. The fact that the phenomenon whereby odor quality changes at different concentrations occurs at the odorant receptor level suggests that individual odor thresholds make a contribution. The present study measured individual odor thresholds in ten subjects using the triangle odor bag method to elucidate trends in changes in odor intensity and pleasant/unpleasant evaluation. In addition, sensory evaluations were carried out in 25 subjects to elucidate the concentrations at which changes in odor quality occurred and characteristics of odor quality. The results obtained are shown below. 1) A hundred-fold difference was observed in individual odor thresholds for dimethyl sulfide. 2) Odor intensity showed greater correlation with odor index than odorant concentration, and it was found necessary to use sensory amounts for odor concentration and odor index to examine odor quality. 3) It was found that a change in odor quality was sensed at a concentration eighty times greater than the odor threshold.Vexatiousness and sharpness increased clearly at a concentration a hundred times greater.