Happy 2016 everyone! To start off another year of food, culture and learning at Midnight Rosewater, we decided to teach you something very different today: SCIENCE!
To be more specific, we want to explain how our bodies sense, perceive and process taste and smell. Hopefully we can offer you a glimpse into your perception world, and show you what makes the things you eat and drink so diverse and great, and explain the mechanism behind your ever changing experience of food. We will hopefully all learn to appreciate the food we eat more!
Before we start, I like to thank Dr. Anastasia Zink (Ph.D. in Neuroscience) again for all the help with this article. Couldn’t have done it without you!

Let’s first clear out some terminology.

Sensation vs. Perception 

There is a difference between sensation and perception. To summarize the difference in one sentence, sensation is your body interacting with the environment and turning the interaction into information that could be relayed through the body; perception is your brain interpreting the sensory information.

Taste (Gustation) vs. Smell (Olfaction) 

At their core, taste (gustation) and smell (olfaction) are more similar than different. Both involve detection of environmental chemicals, both contribute to flavor, both have strong and direct connections to our most basic needs such as thirst, hunger, emotion, sex, and certain forms of memory. The true difference between taste and smell are the receptors used to sense (tongue or nose) and the neural pathways involved for your brain to perceive the information.

Clear? Ok. Moving on.

What do we taste?

Anything you taste, from a ripe apple to a perfectly seared steak, can be broken down to 5 fundamental taste categories: sweet, sour, bitter, salty, and umami.
You are probably familiar with the first four, umami is a Japanese word meaning “savory.” The umami class of taste usually refers to your tongue sensing the presence of amino acids and small peptides.

Wait a second, why isn’t spicy on the list? We will get into this later, but the short answer to this burning question (pun intended) is that spicy is usually perceived as a temperature or pain sensation as opposed to a taste.

Why do we have taste?

We taste sweetness, saltiness and umami-ness because our bodies have an absolute requirement for carbohydrates (sugars etc.), sodium chloride (salt), and amino acids in our diet. We taste bitter and sour because most of the poisons are bitter and spoiled food usually goes sour: this is your body trying to protect itself.

What is flavor?

When you bite into that delicious salmon fillet and say “that tastes great!,” or when you take a sip of a freshly popped champagne (hopefully with hydrosols added to it) and say “emmmmm~delicious~”  what you actually mean to say is that it has great flavor.
Flavor is a combination of taste and smell along a few other sensory inputs, but mainly smell, and it is the perception of all of the sensations. Therefore, flavor is a creature of your brain.
Here's a flavor wheel of commonly described flavors (all rooting from the five basic taste categories).

What affects flavor besides taste and smell?

Well, as said, most of the food’s flavor come from smell-- as much as 80-90% indeed. We know this because when you have a stuffy nose, your food always tastes extra bland. There are also some medical conditions in which patients lose their sense of smell (called anosmia). These patients eventually lose interest in food and often develop malnourishment and depression.
However, several other factors also influence taste and smell heavily:

temperature

At higher temperatures, molecules are more active and bump into things more frequently. What does this mean to a foodie? Higher temps increase the chance that a taste-y molecule, let’s say, a sugar molecule, bumps into it’s matching taste receptor. Every notice a mixed drink or soda get sweeter as it warms up? Yep. That’s because when it was cold, the sugar molecules were moving around less and interacted with fewer sugar receptors.