Sunday, November 27, 2011

Tired of Turkey?

As the turkey was put away, the cranberry sauce packed into tupperware, and the dishes cleaned up Thursday, Americans across the country shared a collective yawn.

Before I get into this post- you may or may not have heard of tryptophan and may or may not believe it to be the source of our Thanksgiving Day sleepiness. To this, I point out that the amount of tryptophan in turkey is high, but not significantly higher than other meats, and shouldn't induce sleepiness much more than eating a rack of ribs.

The sleepiness we find on Thanksgiving may have a number of causes, and turkey may be a part of it, but definitely doesn't work alone.

Normally, our brain absorbs tryptophan and glucose into the brain. The glucose is used for energy and the tryptophan is used to make hormones, nutrients, and chemical messengers.

On Thanksgiving day you just ate a ton of carbohydrates: rolls, stuffing, mashed potatoes, sweet potatoes, casseroles, gravy, cranberries, and pie. When we eat carbs our blood is full of extra glucose molecules.

To keep our blood at normal levels, our body makes insulin, which tells the muscles to clean up and absorb the extra sugars. The muscles do this, leaving the blood with lowered glucose levels, but still the same tryptophan levels. When our brain absorbs the tryptophan and glucose, it absorbs extra tryptophan because of the lowered amount of glucose present to absorb. The tryptophan goes down a chemical pathway, which ends with sleep-promoting melatonin in the brain.


I think its time for a nap now.

Sunday, November 20, 2011

Winter's coming- stay insulated!

Trying to think of a new blog post topic, I decided to ask friends what they wanted to understand the chemistry behind. One friend, Skylar, responded without hesitation to say the spray foam insulation.

Two chemicals come out of a spray gun and upon combining react to form polyurethane in an energy producing reaction. Poly(which means many)urethane(one type of organic compound) is many organic compounds (not urethane, but actually an organic compound called carbamate) linked together.

Upon hitting a surface the new mixture rapidly grows to fill the space it is in, growing to 100 times its original volume. This growth is what makes it so amazing to watch, as it expands from a line of liquid to a wall of solid foam.

Polyurethane comes in many shapes and sizes, determined largely by other chemicals added to the mix. To make spray foam so light and so large, the makers add a chemical that keeps space between the polyurethane molecules. This chemical is called a blowing agent. In many cases water is the blowing agent. With the energy from the combination of the sprayed liquids, water vapor is dispersed throughout the mixture as the foam forms around it. The water then turns into a liquid, leaving voids where it had previously been a gas.

The foam, because it has all these pockets inside, serves as a great thermal insulator and holds heat. In a house, the foam keeps heat from escaping the house, keeping energy bills low in the winter.

The foam is also a great insulator because of the rapid expansion it undergoes. When it expands so quickly, it fills every crevice, leaving few places for heat to escape through exposed walls.

Thursday, November 10, 2011

Poached Eggs

While I can't call myself an expert chef, I do claim to dabble in the culinary arts. I have always loved to cook, and my favorite meal (besides dessert) has always been breakfast. For the most part I think this is because I love baking, and breakfast has so many baked goods associated with it (muffins, coffee cake, pancakes, waffles, bread, scones).

With a love of carbs, eggs have never been my first choice as a breakfast option, but I have a friend and fellow amateur chef/blogger who decided to experiment with eggs. We decided to poach eggs, as that was something neither of us had tried before and looked just challenging enough to be fun.

The general idea of a poached egg is you crack an egg into a pot of hot water, and wait until the egg is cooked just enough to be delicious. We found a few different tips, that (no surprise!) have chemistry behind them if you look closely!

  1. Push the egg whites together to help the poached egg come out in one piece
    • An egg (especially the egg whites) is made up primarily of proteins, which are long molecules all folded up on themselves due to weak bonds within the molecule. When the proteins are heated up, these weak bonds are broken and the protein unfolds, but stronger bonds are formed as the different protein molecules all connect. By pushing the egg whites together, you are helping to create more of those stronger bonds, which keep the cooked egg together.
    • Another fun way to do this was to swirl the water before pouring in the cracked egg. The egg will swirl with the water until it settles down, and the centripetal force of the swirling motion pushes the egg whites together for you into a nice little egg packet.
  2. Add a teaspoon of vinegar to the boiling water to help the egg stick together.
    • The vinegar, like the heat, will break the original weak bonds of the molecule, and make the protein unfold and ready to form stronger bonds. By adding vinegar to the pot of water, when the egg is added, the proteins will be able to stick together faster, and keep it from separating into a white, stringy, watery mess.
  3. Heat the water to almost boiling, then cook for 4-5 minutes
    • If the water is too hot or you cook the egg too long, then the protein molecules in the egg whites form too many of those strong bonds to each other. When these bonds form, they push water out of the egg, which is what causes the egg to solidify. If too much water is pushed out of the egg, like when the egg is heated too long or too much, then it becomes tough and rubbery.
Poached eggs taste delicious (reminiscent of a yummy cheese sauce), are healthy, and not too hard to make. We ate ours over toast and loved it! Next time you are feeling adventurous at breakfast in the kitchen, I'd recommend a poached egg--it will surprise you!

Wednesday, November 2, 2011

Clarifying the fog machine

This past Halloween weekend people across America enjoyed fog machines as special effects in the movies or on TV, to spook the neighbors, or to enhance a haunted house. What is this weird artificial cloud? Where does it come from? How does it work?

Chemistry has all the answers.

Fogs are created by the dispersion of small liquid particles. For artificial fogs, the most common type of fog fluid is made of water and glycols. A glycol is a chemical compound containing oxygen and hydrogen groups that are attracted to water molecules like magnets. The result is intermolecular hydrogen bonding which connects the water molecules to glycol molecules. When these two liquids are heated inside the fog machine, the water particles convert to gas at their boiling point (100°C) and the glycol substances remain liquid, as their boiling point is upwards of 180°C. Because of the intermolecular hydrogen bonding that latches the particles together, the gas released from the fog machine is visible because the gaseous water molecules have liquid glycol molecules attached to them.

While the fog may be spooky, their is no reason to panic. There is nothing magical about its creation. Just the clever application of chemistry in the special effects world.