Taste and smell, and the perception of food flavor

As human beings, we possess an incredible capacity for choice, and one of the most compelling is our relationship with food. However, the choice of foods we try can be influenced by several factors: need, desire, pleasure, among others, which often lead us to seek out something new, reinvent recipes, and even tap into our memories to intensify the encounter with what we seek.

The simple act of eating daily has become something complex and challenges science every day. Studies related to food are frequently published in renowned journals. Some of these report the importance of the five senses in food choice and preference.

The sense of hearing can, for example, evoke a festive memory, such as the sound of a champagne bottle opening or balloons popping, which are called extrinsic factors linked to food. But this sense can also influence food quality, such as its degree of crispiness. The sense of sight helps us choose what to put on our plate, through its colors or presentation methods and formats. The senses of touch, taste, and smell are considered essential when choosing food, because even with your eyes and ears covered, you can tell whether a food is bad, good, or absolutely delicious. The sense of taste, which involves molecules responsible for providing the five basic tastes (sweet, salty, bitter, sour, and umami), has several specificities that involve the presence of specific receptors on the tongue. Smell, on the other hand, is an even more complex system, encompassing a range of molecules that impart aroma to food and allow us to describe the flavor of what we are eating, such as the taste of cheese, peaches, shrimp, etc.

Aromatic stimuli can be reached by the olfactory epithelium through two pathways: nasally, during the act of smelling (orthonasal olfaction), and orally, during food consumption (referred to as retronasal olfaction). Orthonasal olfaction begins with an external stimulus, which travels through the anterior nostril toward the olfactory mucosa during the act of smelling. The retronasal process occurs during chewing and after swallowing, where volatile aromatic molecules are released from the food matrix and reach the nasal cavity through the pharynx, stimulating receptors in the olfactory cleft (Ruijschop et al., 2009).

After contact of aromatic molecules with the olfactory system, specific receptors are expressed in the epithelium, more specifically in the cilia of olfactory neurons, which promote chemical signaling that carries the perception of aromas to the brain. Most genes for olfactory receptors are G-protein coupled, with over 400 genes in this receptor family found in the human genome (Munger et al., 2009; Trimmer et al., 2019).

Indeed, taste and smell are intrinsically linked to flavor and are directly linked to the identity of foods, regardless of reward or pleasure values. Other multisensory studies are being conducted to understand why perceptions vary from individual to individual and how a number of factors can affect our ability to savor a food.³ However, no matter how many studies map our brains or identify receptors, each individual will have different encounters with flavor through their experiences, which will be affected by time, memory, and cultural makeup.