Many mammals use scent marking to indicate territory ownership to other conspecifics. Domestic cats (Felis silvestris catus) perform scent marking by spraying their urine and leaving their feces on the ground around the border of their home range. When other cats find these excretions, they approach these for sniffing, suggesting that feline excretions provide information about the scent owner’s identity and territory for other conspecifics. However, volatile chemical profiles have complex patterns that differ between individuals and are too unstable after marking and too subject to daily variation to be used as scent signals. In this review, we report chemical profiles of feline urine, feces, and anal sac secretions to understand scent communication using species and sex specific compounds and compounds that vary between individuals in cats.

Domestic cats and other Felidae species show the characteristic response to silver vine plants (matatabi in Japanese). This response comprises licking and chewing the leaves, rubbing their faces and heads against the leaves, and rolling over on the leaves. The behavioral significance of the feline response has remained undetermined for over 300 years. Our recent studies demonstrated that the response is beneficial to chemical defense against pest mosquitoes. Here, we review our recent studies uncovering the potent bioactive compound for the response, the underlying mechanism of the response, and the behavioral functions of both “rubbing and rolling” and “licking and chewing”.

Although several microalgae species have been used for industrial purposes, it is generally difficult to visually observe their growth conditions during cultivation. Our group has attempted to develop a way to control algae cultivation, using a method we refer to as “Odor Sensing Cultivation” (OSC). This is a new and simple observation method that is based on the odors produced by algae. In this study, as a representative microalgal species, Scenedesmus sp. was employed. Odors produced from its culture were investigated by olfactory evaluation, chemical identification, and “e-nose” analysis. As a result of olfactory evaluation, “green tea”, “sweet”, and “fishy” were the characteristic odors identified from this species. In the chemical analysis, the odors from this species were identified as 1-nonanal, α-ionone, β-ionone, and tentatively identified as 2-undecenal and acetic acid. Based on the QCM-type e-nose analysis, the odors from this alga and the control medium could be separated. These results suggest that the OSC is applicable as a practical technique for production of this species.

The “stored off-flavor” is one of the unfavorable flavors released by several citrus species when stored at low temperature. The degradation in quality due to the stored off-flavor has been a problem with satsuma mandarins (Citrus unshiu Marc.), a major citrus species in Japan. However, information about this problem is fragmented. To develop a method for determining which satsuma mandarins are suffering from stored off-flavors, our group attempted to define the odor characteristics of stored off-flavors through olfactory evaluation and to identify the compounds responsible for off-flavors using samples of satsuma mandarins stored at low temperature. We found that the odor characteristic “grass-like” was stronger in samples stored at a lower temperature (4 °C) than those stored at room temperature (25 °C). The grass-like odor was defined as the stored off-flavor of satsuma mandarins. Following a chemical analysis using gas chromatogram-olfactometry (GC-O) and GC-MS, the stored off-flavor, grass-like, was identified as p-cymenene.

For strawberry runner roasted tea under development as an effective use of strawberry runners, we performed the sensory evaluation and aroma components of the roasted tea prototyped from five varieties, namely, “Benihoppe,” “Tochiotome,” “Ibarakiss,” “Toukun,” and “Amaekubo.” From sensory testing, “Ibarakiss” and “Benihoppe” were found to have high scores for “grain aroma” and “burnt.” Principal component analysis of the aroma components obtained using gas chromatography-mass spectrometry indicated approximately three groups, and characteristic aroma components were found for each group.