Guidelines for sensory evaluation of electronic cigarettes (II): Odor perception and olfactory fatigue

The second article in the "Guidelines for Sensory Evaluation of Electronic Cigarettes" series mainly explores the issues of odor perception and olfactory fatigue in sensory evaluation of electronic cigarettes. Olfactory fatigue can lead to evaluators being unable to accurately identify subtle differences between samples, thereby affecting the accuracy of the evaluation. The article also introduces two types of olfaction: anterior nasal olfaction and posterior nasal olfaction, as well as their applications in sensory evaluation of electronic cigarettes. Understanding and reducing olfactory fatigue is crucial for practitioners in the electronic cigarette industry.
The first article in this series introduced the relevant content of "e-cigarette smoking evaluation methods". Click on the link below to directly access the previous article.
Guidelines for Sensory Evaluation of Electronic Cigarettes (1): Evaluation Methods
In this issue, we will learn about the relevant content of odor perception and olfactory fatigue in the sensory evaluation of electronic cigarettes. This series will continue to comprehensively and deeply explore the sensory evaluation of electronic cigarettes. Please stay tuned.
Topic 2: Odor perception and olfactory fatigue in sensory evaluation
A thorny problem that electronic cigarette practitioners inevitably encounter during the sensory evaluation process is olfactory fatigue. The appearance of olfactory fatigue can cause evaluators to lose the ability to distinguish subtle differences between samples, and then "randomly select" or "guess" one of the test samples, leading to "guessing behavior" in sensory evaluation, which will seriously affect the accuracy of sensory evaluation conclusions. Even worse, due to face saving, sensory evaluators often choose to hide the fact that they cannot distinguish the small differences between samples.
In practice, guessing behavior caused by olfactory fatigue among evaluators is very common and covert. Such speculative behavior will seriously affect the results of sensory evaluation and subsequent business judgments. Therefore, understanding smell, understanding smell fatigue, and researching how to reduce the impact of smell fatigue are crucial for e-cigarette practitioners.
(1) Olfactory
This section only provides a brief overview from the perspective of e-cigarette practitioners.
So far, there is a general consensus in the academic community on the understanding of olfaction (Figure 1), which is divided into two parts: anterior olfaction and posterior olfaction. When inhaling gas through the human nose, it passes through the red line and uses the front nasal sense of smell for odor perception; When eating food in the oral cavity and inhaling e-cigarettes, they pass through the blue line and use their nasal sense for odor perception. These two olfactory pathways do not occur in isolation, but often work together. The posterior nasal sense of smell can pass through a special olfactory receptor area, allowing for a more comprehensive perception of the flavor of smoke in the oral cavity.
The local circulation evaluation method and the overall circulation evaluation method mentioned in the previous issue mainly use the posterior nasal smell for evaluation, while the nasal suction method is more commonly used in our anterior nasal smell. Therefore, it is difficult to comprehensively evaluate smoke using nasal inhalation method for evaluation.
Now that we have understood the pathways through which the smoke (or aerosol) of e-cigarettes is felt, what happens at the end of these pathways?
The process of perceiving odor through smell is shown in Figure 2: odorous air (chemical signal) binds to our odor receptor, activating it and producing ion surging. The chemical signal is then converted into an electrical signal, which reaches the brain through a series of pathways, forming odor perception.