Chocolate Neurogastronomy

A look at how your brain creates flavour

Flavour is not contained in our food. Nor is simply what we taste and what we smell combined. Flavour is a perception formed in our brain that combines all of our senses, as well as our memories and preconceived ideas. The way we sense the world is unique to us. Individuals have types and quantities of receptors in our mouth and nose. On top of that, we reflect what we taste based on past experience, which are unique to us culturally as well as individually.

Understanding how flavour is created will better help us get the most flavour out of our chocolate. If we better understand how our mouth, tongue, nose, breathing, and thoughts all impact how we experience flavour, we will have more control over it, and help us discover flavours we otherwise would have missed all together. So in essence, understanding neurogastronomy may help you get more satisfaction from your chocolate and food in general.

Taste what I’m talking about

A. Consume Chocolate

When consuming chocolate, it’s important to bite it a few times and move the bits of chocolate around in your mouth. This is because taste buds are not only found on your tongue, but all over the inside of your buccal cavity.

Taste

These taste buds don’t pick up “flavours” such as cherry or chocolate, but rather pick up the 5 tastants, which includes sweet, sour, bitter, salty, and umami (savoury, think mushrooms and meat). In regards to plain dark chocolate, we mostly pay attention to the first three. Some scientists are even suggesting other tastants in addition to these, such as fat. Fat, not as a texture, but as a taste.

This “taste” information is sent to your brain via the spinal cord, and so taste is part of the autonomic nervous system. This means that the response from our brain is very immediate. When something is too bitter or acidic, we know immediately. This was an evolved response in order for our ancestors to avoid poisonous or foul foods.

mouthfeel

This is also the part where we experience the texture of our chocolate, which for many, can make or break how much we enjoy it. Pay attention to how the chocolate feels physically in your mouth. How it melts, how sticky it is, how warm or cool it feels as it melts, how smooth, grainy, creamy, or watery are some traits you may want to pay attention to. This information is also sent to the brain where, mostly based on learned experiences and memories, we judge the chocolate accordingly. Perhaps you grew up with very smooth buttery chocolate, and any chocolate with a hint of graininess would just ruin your experience. Or perhaps you enjoy new food adventures, and the texture is something you can learn to enjoy.

B. Exhale

Everytime we swallow, we automatically exhale. This is probably the most important point to remember if you want to get the most flavour from your fine chocolate. As the chocolate sits and moves around in the mouth, it satures the air in our mouth. Then, as we exhale, the aroma saturated air in our mouth is pushed into our nasopharynx and out through our nostrils. It’s these aromas which gives our chocolate flavour beyond taste (bitter, sweet, sour). It’s what allows us to experience those cherry, honey, and hazelnut notes in our plain dark chocolate.

The air that passes through here carries the aroma molecules to our olfactory receptor nerves which extend into the epithelium (the area inside the grey rectangle). These nerves sit at the roof of your nasopharynx, and grow directly from your brain and travel into the nasopharynx via little holes in your skull that allows them to pass. These olfactory nerves are the only part of our brain that extends outside the cranium.

The reason this step is so important, is that each time we exhale, we send more and more aroma molecules to these receptors. This is why it is important to constantly exhale through your nose as you try and "taste" and articulate the flavours in your chocolate. The more you exhale, the more information you offer your olfactory nerve receptors, and the easier it will be to interpret the flavour. These aromas can be subtle, and don’t last for long, so the more you breath, the more time you give your brain to experience all these flavours.

If you are finding it difficult to detect those flavour notes suggested on the wrapper of your chocolate bar, spend more time exhaling through your nose as you consume the chocolate. You’ll find it makes it easier to pick up those aromas, whether or not you are able to articulate them.

C. Olfactory Bulb

Here is where things begin to get more complex. Know that there are about 400 types of olfactory receptor nerves, and thousands upon thousands of actual individual nerves of each type. All these olfactory receptors within the nasopharynx that were stimulated by those chocolate aromas travel up and join together in what is called the olfactory bulb. Within the bulb, the nerves are organized by type, so each type of receptor join within the olfactory bulb at what are called glomeruli.

The image here depicts the same olfactory bulbs three times, but little circles within it are the glomeruli. Specific aroma molecules activate specific neurons. These neurons meet in the Olfactory Bulb (OB), and match up with other like neurons with the same receptors into the glomeruli. Depending on which neurons become excited, their corresponding glomeruli create a pattern in the olfactory bulb. It is this pattern which represents what the aromas are.

However, the olfactory bulb doesn’t determine the aroma or flavour. This pattern is sent to the Olfactory Cortex (OC) of the brain where the pattern is transcribed into something our brain understands.

D. Olfactory Cortex

This is where the external world meets our internal perceptions. That pattern formed in the Olfactory Bulb is received here in the Olfactory Cortex, and processed according to the information already stored in our brains.

The reason you can smell is because of the Olfactory Cortex. It is the part of the olfactory system that learns. It learns by matching previous odour information with new information. The different patterns that the Olfactory Bulb presents here are stored and new patterns are compared to the old ones. The more you expose yourself to dark chocolates with different flavour profiles, the more context your OC will have to reflect on when you try a new chocolate.

The information received is transcribed into information our brain can interpret and understand. The Olfactory Cortex takes all this information and forms what is known as an “Odour Object.” Like a visual object, which is based on shapes and colours, the odour object is based on all the information received from the olfactory bulb. This odour object is combined with our other senses to create what we know as "flavour.”

E. Memory & Emotion

This information is also sent to the areas of the brain that pertain to your emotions, memory, and decision making. These included parts of the brain such as the insula (emotion & cravings), amygdala (emotion) and parahippocampal gyrus (memory and emotion).

At this point, our judgements and preferences kick in and we respond to the flavours accordingly. Past experience with certain aromas or flavours are sparked in our memory. If we have had an adverse reaction to a certain food or smell, then if our chocolate brings up those memories, we will respond accordingly. For instance, if the flavour profile of a chocolate bar reminds you of a bad meal or food that make you sick because of some common flavour, then you will likely reject that chocolate and never want to eat it again.

This has happened to me, when a certain chocolate bar which I enjoyed, had an endnote that reminded me of a cheap soup stock. I couldn’t get that image out of my mind even after consuming the chocolate another day. Unfortunately I could never really enjoy that chocolate fully because of the memory and emotions I have with the endnote.

This is also where the flavours of chocolate become subjective. We all have past experiences, and what we compare the realtime flavours with will be different for all of us. As well, our aversions or cravings differ to the point that we may love or reject chocolate bars according to these alone. Not even the best chocolate judge can push back the awful emotions they have when tasting chocolates at a competition that may remind them of something else.

F. Other Senses

The retronasal olfaction system is also tied with our other senses. As a whole, all these inputs add up to form our perception of the flavour we just encountered. We discussed taste, aroma (via from exhaling), but there is also the information we receive from sight, sound, texture, and external odours.

Sight

How a chocolate presents itself has a big impact on how we judge how much we enjoy it, and may even influence our flavour analysis. The colour, the shine or lack of, and even the packaging will all influence our judgement.

As we grow, we learn to make associations. For example, a chocolate lighter in colour, or with a red hue, may influence our expectations of what it may taste like. A lighter brown may suggest a less intense, sweeter chocolate. A red hue in the chocolate make push the idea that it may be fruity. Our minds then may exaggerate our experience based on what we expected, tasting more fruity than it actually does. The opposite may be true too, if we expected that lighter shade of brown chocolate to be sweeter, but instead was a little bitter, we may feel the chocolate is even more bitter than it is due to our expectation of it being sweet.

Pretty packaging may also interfere with our discernment between fine and not so fine chocolate. We have expectations that beautiful packaging or a well moulded bar will likely taste better. We may enjoy the chocolate much more than we would had it be presented differently.

Sound

The sounds our food makes does impact our interpretation and satisfaction of it. A study where individuals consumed chips illustrates this very well. They consumed chips with headphones on that blocked out external sounds. When they would bite a chip, someone would play a sound or not play any sound through the headphones. When the experimenter played a loud crunch sound the individual eating the chip would rate it as fresh and crisp. When the experiment played a quiet sound or no sound, the individual would rate the chip as not being fresh. They were the same chips! However, their interpretation of it was altered according to what they heard.

Well tempered chocolate makes a snap sound when you bite it. Crispness is a quality that is very desirable, and when we hear that snap or pop from biting a well tempered chocolate, our brains respond accordingly.

As well, external sounds such as the environment we are in, which in turn influences our mood and emotions, may also add to the way we interpret our flavour experience.

Texture

We discussed texture in Part A. The way the chocolate feels in our mouth has an impact on whether we enjoy or reject it as “good” or “bad” chocolate. We have expectations of chocolate, based on the type of chocolate we grew up on. Some may have been creamier, some may have grew up with chocolate which contained texture. A study on chocolate specifically found that people associated creaminess with sweetness as well. It’s safe to say that the information gathered about the texture of our chocolate influences our flavour perception.

Smell

Here I’m talking about external smells, not the aromas coming from the chocolate within our mouths. You’ll find that tasting chocolate in different environments will alter our perception of the flavours. Strong odours will impede our ability to articulate flavours, or may mask them all together.

I remember conducting a tasting once with a group, and many of them found a certain chocolate to be very earthy, like mushroom. This was also the same point in time when the host was roasting mushrooms in the oven. I pointed that out, and everyone laughed. Needless to say, mushroom came up quite often after that.

Just like sight and sound, surrounding odours also influence our emotions and evoke memories. Since flavour is so intertwined with this part of our brain, chances are this may alter our flavour perception as well. Sometimes surrounding odours can’t be avoided, but they should be acknowledged.

Conclusion

It may take a couple times to read through this in order to grasp some of the ideas, and that’s okay. If you struggle with articulating or even picking up the fine flavours in your dark chocolate, don’t get discouraged!

Continue to taste, mindfully. Pay attention to what your body is doing (breath), your thoughts, your surroundings, and give yourself time. Learning to taste fine chocolate and articulate it is like learning a new language from scratch. Even if you know a few of the words, making sense of all the new sounds and meanings takes time, but most of all, takes plenty of practise. At least with chocolate your practise isn’t phonetics and grammar, but eating delicious chocolate!

Chocolate Neurogastronomy