When you eat, aroma molecules can travel from your mouth through the back of your throat and up into your nose. Holding your nose often means fewer of them reach your smell receptors. You can still taste sweetness and tartness, but the familiar apple aroma may be harder to notice.
You can smell an apple slice before you bite into it. As you chew, you recognize that same fruity smell, even though the slice is now in your mouth. How can your nose smell something in your mouth?
Smells can reach your nose two ways
When you sniff an apple, aroma molecules enter through your nostrils. Eating the apple releases aroma molecules too. Air can carry them from the back of your mouth through your throat and up into your nose. This is called retronasal smell. Both routes lead to smell receptors high in the nose.
Your brain puts the signals together
Taste buds in your mouth pick up sweetness and sourness, for example. Your nose picks up the fruity smell. You can also feel whether the apple is crunchy, juicy or cool. Your brain puts these sensations together.
When you hold your nose, less air flows through it. That often makes the aroma from your mouth harder to notice. You can still tell how sweet the apple is and what it feels like in your mouth.
When do you notice the apple aroma?
- Sit at a table and smell some applesauce that you know you can eat.
- Gently hold your nose and put a tiny dab of applesauce on your tongue. Do you notice sweetness or tartness first?
- Let go right away, before you swallow. Breathe normally. Does the fruity aroma become easier to notice?
You can skip this activity. Hold your nose only for a moment and let go right away if it feels uncomfortable.
The takeaway
Your nose can smell while you eat. It picks up aroma molecules that travel from the mouth through the back of the throat. Your brain blends that smell with what you taste and feel in your mouth.
Which route can aroma molecules take while you eat?
Sources & further reading
NIH / NIDCD · How does your sense of taste work? ↗Ni et al. · Optimal directional volatile transport in retronasal olfaction (PNAS) ↗University of Washington · Neuroscience for Kids: Taste ↗Our stories explain the main idea in our own words. Pictures and models simplify reality and are not drawn to scale.
