Odor/taste integration and the perception of flavor

Overview of mouthfeel from the perspective of sensory scientists in industry

Mouthfeel is vital in consumer acceptance of foods and beverages. Despite the critical role mouthfeel plays in product development, the concept is often poorly understood and subject to various interpretations. Within this review, five topics of interest are discussed to provide a better understanding of the mouthfeel attribute-the definition, the perception, the importance, the influencing factors, and the methods of measurement of mouthfeel. Mouthfeel encompasses multiple attributes. Although mouthfeel attributes perceived through physical and chemical perceptions, such as cooling and heating, are understood as mouthfeel, attributes perceived through mechanoreceptors, such as creaminess and thickness, are more challenging due to varying opinions on texture and mouthfeel. Other factors, like food composition and temperature, are also vital in understanding the overall effect of mouthfeel in food and beverages. Including all perceived attributes and factors is important for consumer acceptance of products and for developing consistent evaluation of products. Other topics to consider include the dynamic aspects of oral processing and cultural backgrounds as these topics create additional intricacies in defining and understanding mouthfeel perception. Despite the lack of instrumental methodology available to measure mouthfeel attributes, trained panelists can be used to predict facets of mouthfeel in the eating experience. When designing sensory testing for trained panelists, experimental conditions and a product-specific lexicon are important factors to consider. Overall, understanding of the mouthfeel attributes and their role in consumer preference for different types of food and beverages continues to evolve.

Modification of the Peripheral Olfactory System by Electronic Cigarettes

Electronic cigarettes (e-cigs) are used by millions of adolescents and adults worldwide. Commercial e-liquids typically contain flavorants, propylene glycol, and vegetable glycerin with or without nicotine. These chemical constituents are detected and evaluated by chemosensory systems to guide and modulate vaping behavior and product choices of e-cig users. The flavorants in e-liquids are marketing tools. They evoke sensory percepts of appealing flavors through activation of chemical sensory systems to promote the initiation and sustained use of e-cigs. The vast majority of flavorants in e-liquids are volatile odorants, and as such, the olfactory system plays a dominant role in perceiving these molecules that enter the nasal cavity either orthonasally or retronasally during vaping. In addition to flavorants, e-cig aerosol contains a variety of by-products generated through heating the e-liquids, including odorous irritants, toxicants, and heavy metals. These harmful substances can directly and adversely impact the main olfactory epithelium (MOE). In this article, we first discuss the olfactory contribution to e-cig flavor perception. We then provide information on MOE cell types and their major functions in olfaction and epithelial maintenance. Olfactory detection of flavorants, nicotine, and odorous irritants and toxicants are also discussed. Finally, we discuss the cumulated data on modification of the MOE by flavorant exposure and toxicological impacts of formaldehyde, acrolein, and heavy metals. Together, the information presented in this overview may provide insight into how e-cig exposure may modify the olfactory system and adversely impact human health through the alteration of the chemosensory factor driving e-cig use behavior and product selections. © 2021 American Physiological Society. Compr Physiol 11:2621-2644, 2021.