Nosy confirmation: reconstitution of the characteristic odor of softwood via quantitative analysis and human sensory evaluation

Research progress in the synthesis of stable isotopes of food flavour compounds

Stable isotope dilution analysis (SIDA) is a quantitative method widely used in the determination of food flavour components because of its high efficiency and precision. However, many stable isotope reagents cannot be purchased through commercial channels. In this paper, the basic principle of stable isotope dilution analysis is introduced and its historical progress in food flavour analysis are examined. Then, the preparation methods of stable isotope analysis of food flavour compounds in recent years were compiled. In the literature reviewed, from 2012 to 2022, there were 185 stable isotopes of food flavour compounds used for food flavour analysis, of which 126 compounds can be purchased commercially and 59 compounds must be prepared in the laboratory. This review aims to present the methods used in the synthesis of stable isotopes to facilitate the development of food flavour analysis using stable isotope technology.

Smells like new car or rather like an old carriage? - Resolution of the decay behavior of odorants in vehicle cabins during usage

The typical new car smell is not only perceived directly after vehicle delivery. Vehicle interiors maintain their characteristic odors for a period of time during use even though the gas composition of the vehicle interior changes due to external influences. To obtain deeper insights into the odorant composition of a passenger cabin, this study aimed at characterizing the gas phase of two vehicle interiors at defined time intervals after vehicle delivery, and use by a customer in a controlled environment using a targeted odorant analysis. Thereby, the decrease in the general emissions in the cars did not coincide with the decay behavior of the odorants due to the chemical characteristics such as polarity of the odorants. Identification of the odorants in the vehicle interior during use revealed three groups of odor contributors exhibiting different decay behaviors: (i) odorants vaporizing rapidly via elevated temperature; (ii) odorants released by continued diffusion from materials; and (iii) fragrance chemicals of the customer. After 23 weeks of vehicle use, octanal, p-chloro-m-cresol, nonanal, p-tert-butylphenol, γ-nonalactone, and unsaturated aldehydes and ketones represented the most important odorants in the vehicle interior constituting the investigated car odor. The results of a descriptive sensory analysis corresponded with the identified odorants.

Follow your nose - Traveling the world of odorants in new cars

Volatile organic compounds of the vehicle interior are well investigated, but only limited information is available on the odorants of the passenger cabin. To close this gap, we aimed at specifically elucidating the odor, as a general proof of principle, of two new cars with different seat upholstery in a controlled environment using a targeted odorant analysis. In a first step, odor profiles were evaluated by a descriptive sensory analysis. Then, potent odorants of the passenger cabins were characterized by gas chromatography-olfactometry and ranked according to their odor potency via odor extract dilution analysis. Using this approach, 41 potent odorants were detected, and 39 odorants were successfully identified by two-dimensional gas chromatography-mass spectrometry/olfactometry. In a third step, important odorants of the vehicle interior were quantified by means of internal standard addition. The most dominant odorants could be assigned to several specific substance classes comprising esters, saturated and unsaturated aldehydes, unsaturated ketones, rose ketones, phenolic and benzene derivatives, and pyrazines, occurring in a concentration range between 0.05 and 219 ng/L in air. Of these potent odorants, the aldehydes 2-butylhept-2-enal, 2-propyloct-2-enal, and (Z)-2-butyloct-2-enal are reported here for the first time as odorants in the environment of a passenger cabin.