Research paper
A study on the odor characteristics of phenylacetic acid and nonanoic acid
2018 Volume 49 Issue 1 Pages 29-37
Details
2018 Volume 49 Issue 1 Pages 29-37
Phenylacetic acid and nonanoic acid are components found in the living environment that give off an unpleasant odor. Although these substances are very common in our daily environment, they have not been recognized as the cause of unpleasant odors, because they have a relatively high boiling point and are subject to less general evapotranspiration. We proposed to measure the odor threshold by the Triangle Odor Bag Method and evaluate the value of odor quality; research participants sniffed four gasbags at predetermined concentrations.
The results are below:
1. The odor threshold of phenylacetic acid is 7.3×10－7 (ppm) and nonanoic acid is 7.1×10－4 (ppm). That is equal or lower than the offensive odor substances such as fatty acids and aldehydes in the previous studies, and the existence of odor was distinguished in a low concentration.
2. The odor quality was evaluated by 138 research participants. The evaluation items are odor intensity and pleasant/unpleasant level, and so on. The results show the score of odor intensity and level of unpleasantness become higher as the odor concentration increase in both substances.
3. Factor analysis based on the kind of odor by the SD method plotted a factor score on the extracted axis, for the increase of unpleasantness, solid feeling and acridity score with odor concentration.
4. Odor index of phenylacetic acid is 17 and nonanoic acid is 21, which is calculated at the 20% of non-acceptance rates. These were both higher than the odor of restroom and personal odor of the past study and it was understood these were allowable levels of odor at a high concentration when they existed in the air.
