Tasting Tuesday: Retronasal Aroma (The other type of smell!)

The retronasal pathway is extremely important to sensory analysis even if you’ve never heard of it!

Last week you met your good friends: the olfactory receptors. These special cells that enable our sense of smell are housed in the olfactory epithelium, which talks to your olfactory bulb…which is where your brain synthesizes scent. Wow, you’re about to be fun at dinner parties! 

This week, we’re looking at the other pathway aroma can travel to reach those aroma receptors: up the back of your throat. Every time you swallow, a little gas is naturally pushed up this pathway. This gas brings aroma compounds to your olfactory receptors. You also make use of this pathway when you take a typical sniff with your mouth slightly open. However, the is a special technique to really get the most out of this underutilized aroma pathway. I call it the retronasal sniff.

One thing to note is this is not your average sniff, it’s multi-step and takes a little coordination, so don’t get discouraged when it takes some practice. It usually takes three or four times when I’m there in person to teach at workshops and it’s even harder without an instructor there!

The Retronasal Sniff, Step-by-Step

1. Hold your nose 
2. Inhale 
3. Take a medium sized sip of beer
4. Close your lips tightly 
5. Swish the beer around gently to cover all surfaces of your tongue 
6. Keeping your lips close simultaneously swallow and exhale out your nose
7. Keep your lips closed and see if a flavor “appears” in your mouth 

It’s easier to understand when you see these steps in action:

Smelling on Both Sides of The Breath

I like to think of the two types of aroma perception as “breathing in” vs “breathing out” or even pulling vs pushing. We’re used to inhaling a scent but with retronasal aroma we’re exhaling to perceive that same scent. Instead of pulling odor compounds up to the olfactory epithelium, we’re pushing them there. So, we can detect scent on both sides of each breath if we really focus on it.

Using retronasal olfaction is one of the best ways to attune yourself to the fact that much of what we think we are tasting we are actually smelling. When you successfully complete a retronasal sniff you’ll notice the sensation of flavor filling your mouth. Even though it happens in the mouth it is the olfactory receptors “creating” that flavor. (Our gustatory receptors, housed in our taste buds, get all the credit for flavor simply because of their location!)

To guarantee a noticeable experience of that sensation complete a retronasal sniff with a German weissbier (also known as Hefeweizen). Isoamyl acetate is signature to this style of beer and has a very strong retronasal aroma. When you perform a retronasal sniff, the flavor in your mouth will distinctly transform to Banana Runts, Banana Laffy Taffy, or Banana Bread depending on the beer and which of those flavors you identify with most. (To learn more about isoamyl acetate and other flavor active compounds in beer, check out my ebook!)

This step, the retornasal sniff, is an important bridge between aroma and taste as we progress down the tasting technique. Next week we’ll look at dissecting what you sensed through both types of “sniffs” (orthonasal and retronasal). See you then.

Oh and let me know what questions you have in the comments or @beerswithmandy so I can incorporate them into future Tasting Tuesdays.

Further reading on olfaction: The Role of Ortho-Retronasal Olfaction in Mammalian Cortical Evolution