Much of what we taste is actually related to smell. Research indicates that 70-75% of what we perceive as taste is dependent on our sense of smell.
Imagine the smell of a freshly baked cupcake...
Are you hungry yet? I know I am. But I've always been curious about what causes some things to have smells (or good smells) and others to lack an aroma.
Smells are caused by small chemicals reaching your olfactory receptors. These molecules have to be small enough to become volatile (or change from a solid or iquid to a gas to reach your nose) or somehow be propelled into your nose (maybe by a spray?).
Sometimes things have a permeating smell that you associate with that item in its normal state. For instance, stinky cheeses and banana smell are really well known and are associated with the foods from the time you pick them up in the grocery store.
Sometimes you have to 'open' foods to get the best smell from them. Like onions and garlic.
They seem perfectly innocent....then the minute you start cutting them, they make you cry and makes your hands stink!
Finally, some things smell when they are fresh, but seem to lose their smell (and thus taste) when they sit out or dry...
Popcorn and fresh herbs have strong, distinct smells when they are fresh. They lose those flavors if they sit out.
Now that we have determined the multiple ways that foods have smell, let's talk about what causes those smells.
Release of odor causing molecules
In the case of many herbs and spices, molecules that cause the smells are pent up inside special organs that hold the molecules in their liquid phase. These organs, or sacs, hold in the molecules, which are normally compressed into oils. When the organs are cut open, such as when you cut herbs or grind spices, they release these volatile liquids into the environment, where they immediately evaporate into your nose.
For herbs such as mint and basil, these organs are called tricomes. They jut out from the outside of leaves. When leaves get crushed, dried, or frozen, the tricomes will break open or even fall off. That is why herbs with these glands are so much better when they are fresh.
For foods like onion and garlic, the molecule responsible for the acrid smell that makes us cry isn't even created until we break open the cells.
Garlic and onion contain the enzyme alliinase, which breaks down sulfur containing compounds into their smaller, more volatile components. This is used by the plant to prevent herbivores and insects from damaging the plant. When the plant senses it is in physical danger, it releases alliinase and the stinky compounds are made to deter the pesky pests.
We're kind of pesky pests ourselves, and we actually cause the cell to malfunction when we break open the garlic bulb or onion. The allinase pours into the cell, destroying everything in its path and causing sulfur containing compounds to flood the air. And then we cry.
Mwahahahahahahahah! I've been waiting for an excuse to do that.
Water vapor or other propellant
Propellants made the news when I was a kid because our cans of Aqua Net hairspray were evidently full of these fluorocarbons that were destroying the ozone layer. These propellants made the sticky glue that made the hairspray become....well, a spray.
The same thing happens naturally in food. When you walk into a house where a stew is cooking or a soup is boiling, the molecules that are in the meats and vegetables are carried into the air on water vapor. The energy of the water vapor allows things to get into the air that would normally be too heavy or soluble to do so.
Another example is popcorn. Popcorn seed is rather boring. No smell. No taste. When we cook popcorn, the water inside the kernel gets excited and gains energy. It explodes the inside of the popcorn seed, and the white structure is the cooked starch that was stored inside the seed. The water vapor then carries that typical popcorn smell into the air.
Now we know HOW things have smells...but what molecules cause these smells? Well, it differs between foods and it is really dependent on the chemical makeup of the food. I don't want to scare off my approximately 5 readers with chemical structures (I can hear you breathing a sigh of relief over the internet!), but I do want to make one point.
One-note vs. the 'Bouquet'
Sometimes we'll hear a snobby wine or food guru describing the types of flavors and smells - or 'notes' - contained in a wine or food. Those are hard for the typical person to pick-up. But they are on to something. Some smells are derived from only one molecule. Things like popcorn (2-acetyl-1-pyrroline, if you cared to know) and cinnamon (cinnamaldehyde...) are one-note. They are composed of only one major scented molecule. However, coffee and peanuts are terribly complex. It was recently estimated that over 36 molecules are responsible for the complex smell of roasted peanuts, with 28 of them being required for positive identification. These types of foods are described as having a bouquet of compounds that make up the identified taste or smell.
I hoped you learned something, but I know you're just here for the giveaway ;)
Nothing makes the holidays special like walking into a house filled with the smell of baking cookies (see how it ties in?!?!?). This week I wanted to give my own house this smell, so I made some delicious shortbread thumbprint cookies:
My thumbprint cookies were made with triple berry jam, blueberry jam, and homemade raspberry jam. I now have too many cookies in my house. I'm so excited about this product that I want you to try the jam as well!
I will give you:
1) 6 thumbprint cookies in an assortment of three flavors
2) Two jars of Smucker's jam (one for you...and one to share? Or just two for you!)
3) The cookie recipe for your own holiday fun.
If you want this, leave a comment telling me your favorite smell (food related or otherwise). You can also post this to your facebook page and leave me the link in the comments OR post about it on your own blog and leave a comment to make sure I see it. You have until 5pm on Friday, November 26. The package will go out the following Monday, so you can have them for turkey day!
Back soon with more fun and nerdy posts.