- Have you ever experienced a moment while walking through downtown Buffalo on your way to a Sabres game, or when exploring Canalside, when suddenly your senses are overwhelmed with a lovely scent that brings back memories of grandma's cookies?

On certain days in Buffalo, New York, when the wind is just right, the city smells like Cheerios.

That's right, Cheerios.

The sweet aroma from roasting oats has been radiating from the General Mills plant along the Buffalo waterfront since 1941.

Captivating the olfactory senses of residents and visitors alike.

In fact, in 2018, Buffalo was named one of the top 10 smelliest cities in the United States.

Smelly in a good way, of course.

In this episode of, "Compact Science", we are going to stop and smell the Cheerios, then dive into kitchen chemistry and explore the science of browning, aroma and flavor.

(upbeat music) (upbeat music ends) (upbeat music) ♪ Cheerios, Cheerios ♪ - [Narrator] Yes, Cheerios, the cereal that's shaped like a little letter O.

No other cereal is like Cheerios, the only ready to eat cereal with this wonderful toasted oat flavor.

A breakfast- - But why does Buffalo sometimes smell like cereal?

First, we have to look at what causes smells in the first place.

Smells all start with molecules, the building blocks of a lot of the matter in our world.

An odor can be made by a single type of molecule or a mix of them.

The smell of chocolate, for example, is a mix of as many as 77 different molecules.

Individually, some of these molecules can smell terrible, like vinegar- - Ew.

- Or rotten garbage.

- Gross.

- But the mixture of all the molecules can make something smell downright delicious.

In humans, these scent molecules bind to receptors in your nose, which sends a message to your brain.

Your brain then interprets the smells and identifies them.

The smell can tell us if something is dangerous or if it could be delicious.

It's one of the body's many defense mechanisms.

Back to the cereal, what molecules make it smell so good?

Foods are a combination of different chemicals, lipids or fats, (whooshing) carbohydrates like starches and sugars and amino acids like proteins, so think meat, nuts, or beans.

When we cook food, these different chemicals change and they can't be changed back.

For example, cookie dough, once you bake the cookies, you can't change them back to the raw cookie dough.

These are chemical reactions.

People have known since ancient times that foods take on new aromas and tastes as they brown.

But it was only in the last century that someone figured out why.

When certain foods are heated, the sugars and the amino acids interact with each other in a phenomenon known as the Maillard reaction.

They form a bunch of new compounds with fancy names like melanoidins, furfurals and pyrezines.

While scientists don't know everything about the Maillard reaction, we know one thing, it makes everything delicious.

The Maillard reaction is often called the browning reaction.

It is what is responsible for the aroma of foods as they cook.

First described in 1912 by French chemist, Louis-Camille Maillard, the Maillard reaction occurs within certain temperatures, so 280 to 330 degrees Fahrenheit.

(whooshing) And it can create hundreds of different types of scent molecules.

This remarkable chemical process is the reason for the deliciousness that comes with the brown coloring on cooked foods, like french fries, toasted marshmallows, fried dumplings, grilled cheese, roasted veggies and even coffee beans.

The Maillard reaction happens when you heat a mixture of sugars and proteins, both of which are in, you guessed it, Cheerios.

When General Mills bakes their cereal, the dry heat takes away all the moisture in the cereal, allowing for the Maillard reactions to work their magic, forming new molecules that smell and taste great.

It's not just delicious, it's science.

(upbeat music) From the golden brown crust on freshly baked bread to the tantalizing smells emanating from a searing steak, the Maillard reaction is responsible for many of the sensory experiences we associate with cooking.

It's like a secret handshake between amino acids, the building blocks of proteins; And simple sugars, so those sweet molecules.

When they meet during cooking, they throw a delightful party.

You've probably used the Maillard reaction to get food to look and taste how you want without even knowing what it is.

The final taste and browning effect depend on the amount of sugar, water and protein in the food.

While they don't seem sweet at first, onions are chockfull of sugars and amino acids, just the things we need to see and smell the Maillard reaction at work.

I'm going to add them to the pan and turn up the heat.

This will make the carbohydrates in the onions start to break down.

These sugars then bind to the amino acids.

(stove clicking) (upbeat music) (onions clattering) (upbeat music) Oh, this just smells like a delight.

This might take a while, but there are a few things that we can do to help speed up the process.

We can add a protein like eggs or milk.

So these contain amino acids that readily participate in the Maillard reaction.

So I'm going to add a little bit of butter and see if we can help move things along.

(sizzling) (upbeat music) When you cut them down smaller, it also increases the overall surface area, which means that there are more places for chemical reactions to take place.

Ha ha.

So if you have like big honking, like big, big chunks of onions, it takes longer.

We can also increase the temperature, higher temperatures speed up the Maillard reaction.

So let's turn the heat up a bit.

(sizzling) (upbeat music) Let's adjust the pH.

Alkaline conditions favor the Maillard reaction.

You can achieve this by adding a pinch of baking soda to your recipe.

This not only speeds up the browning, but also imparts a sweet and caramel like flavor to the food.

It's breaking down remarkably quickly, this is fun.

Okay.

(upbeat music) Oh, check this out, it's working.

Wow.

The amino acids and the proteins in the onions have reacted with the sugars, creating a symphony of different flavors.

So the next time you catch that freshly baked smell of Cheerios wafting through the air, or you savor perfectly caramelized onions or a warm chocolate chip cookie, give a nod to the Maillard reaction, it's the unsung hero of deliciousness.

(upbeat music) (electricity buzzing) We learned about food chemistry and the vital role the Maillard reaction plays in the smell, taste and appearance.

If you are interested in learning more, check out our, "Compact Science", Viewer Challenge.

We have a fun experiment you can try at home to explore your sense of smell.

Get all the instructions on our website and be sure to share back your results.

I'm Sarajane Gomlak-Green, and you've been watching, "Compact Science".

Until next time, stay curious.

(upbeat music) (upbeat music ends) - [Narrator 2] "Compact Science" is funded in part by the Joy Family Foundation and by the New York State Education Department.

- The final taste and browning effect depend on the mount...

The Mount.

(sizzling) I lost an onion.

And sometimes we get messes in the kitchen.

This is actually pretty mild compared to my normal life.

Give a nod to the Maillard reaction.

It's the unsung... (upbeat music ends) Unsung, unsung.