As odor expressions of specified odor substances, fixed expressions such as “like urine” for ammonia and “like rotten egg” for hydrogen sulfide have been used. However, since the language used in everyday life has changed over time, it might be difficult to imagine the quality of odor from the fixed expressions. In order to explore the appropriate odor expression for each of specified odor substances, we examined the odor quality of them in this study. Odor intensities of the odor samples were adjusted to around 3. The investigation items, odor intensity, sniffing experience, and the degree of matching with 250 odor expressions, were evaluated by 42 college students. The experimental results showed that methyl mercaptan, hydrogen sulfide, trimethylamine, isobutyraldehyde and isovaleric acid were in high degree of matching with the conventional expressions. In other substances, abstract expressions such as “unique” and “muffled” were observed. In addition, objects and state expressions that differ from conventional expressions were also identified. It was speculated that one of the factors that influence the degree of matching of odor expressions is the background of the times.

The several microalgae species have been used for food materials and industrial purposes. On the other hand, it is generally difficult to visually observe their growth conditions during cultivation. Our group has attempted to develop a simple way to control algae cultivation using “odor” released from them that we refer to as “Odor Sensing Cultivation (OSC)”. The aim of this study was to make clear the temporal trend of odor characters and its strength produced from them according to their growth stage by the technique of sensory (olfactory) evaluation and chemical analysis to develop OSC, using Scenedesmus sp., a representative microalgal species. As a result of olfactory evaluation with gas chromatograph-olfactometry (GC-O), temporal trend of odor strength on four specific odor compounds showed increasing trend according to their growth stage. The seven specific volatile organic compounds (VOCs) from its cultures were tentatively identified using gas chromatograph mass spectrometry (GC-MS) with comprehensive non-target analysis that showed increasing trend according to its growth stage. To assess and control the growth stage of algae cultivation with OSC, four specific odor could be used for indicator of olfactory evaluation, and seven specific VOCs could be used for indicative chemicals detecting with instrumental analysis (such as e-nose and/or mobile GC-MS).

The odorous substances in the sweet potato shochu (25% ethanol content) were extracted and concentrated 20 times. The solution was fractionated at 5.0 mL intervals using gel permeation chromatography (GPC) column with polyvinyl alcohol as the functional group. Ethyl acetate/acetone (1 : 1) was used as the GPC eluent. The fractionated solutions were analyzed by GC-MS. The full scan mode was used to identify the odorous substances, whereas the SIM mode was used to quantify the target substances. The threshold for an odorous substance was determined using a test solution of the target substance dissolved in the GPC eluent. The flavor intensity was calculated by dividing the concentration of the odorous substance by its threshold. Three types of sweet potato shochu (D, E, and F) were compared in terms of the flavor intensity of their odorous substances. Our results revealed that shochu D, which had a fragrant violet-flavor, exhibited larger limonene, β-ionone, and vanillin flavor intensities than those of shochu E, and F. Moreover, shochu E demonstrated larger β-phenetyl alcohol flavor intensity but smaller vanillin flavor intensity compared with shochu F.

Pro-fragrances synthesized using octanal as a fragrance afforded pro-fragrance/cyclodextrin (CD) complexes. The pro-fragrance/α-CD complex promoted release of fragrance, while pro-fragrance/β,γ-CD complexes inhibited. Interaction between pro-fragrance and CD as well as cavity size of CD affected release and hydrolysis of pro-fragrance in complex.