5 Differences between taste and smell

Chemosensory perception of food occurs in the mouth and nose. The integration of taste and aroma perceived by these organs together enable us to perceive flavor of a food. Think about strawberry candy. It probably has a red color, which gives you the expectation it will taste like strawberry, as perceived by visual cues. When tasting, it will give a sweet and sour taste, together with a strawberry aroma, this together gives a strawberry flavor. Without being able to smell the strawberry aroma, the candy would only give a sweet and sour taste. The same goes for lemon candy, without being able to smell the lemon aroma, the candy would only give a sweet and sour taste (probably sourer and less sweet compared to the strawberry candy).

As you may have read in the previous chapters, perception of taste and smell has different pathways. Describing smells can be challenging, as many different kinds of smells exist, and because they are often tied to personal memories and emotions. Information of taste signals first goes to the brainstem and is further transported from there. Furthermore, an endless number of smells can be identified, against only five or possibly six basic tastes. The explanation for this is combinatorial coding of olfaction versus labelled line coding in taste, as is further explained in the image below. Labelled line coding in taste perception refers to the idea that each taste quality is transmitted by specific, dedicated pathways to the brain. However, each taste quality can be triggered by multiple tastants, for example, sweet taste can be detected by different sugars and artificial sweeteners, and bitter taste can be recognized by a variety of bitter compounds through different receptors. Tastes can also be detected by multiple types of receptors. For instance, bitter tastes can be sensed by various receptors in the TAS2R family, umami by TAS1R1 and TAS1R3, and sweet by TAS1R2 and TAS1R3 receptors.

Smell and taste can also interact, to give flavor to a food. Now you can think about different ingredients (chemical compounds) in food whether they give a flavor, taste, or aroma to the food, and how this information is transported to different brain areas. The differences and interactions between flavor, taste and aroma are further explained in the video.