Cool Colligative Properties, Really Really Cool

So, as I mentioned before there are a lot of things I love about August. There is one thing I don't, the heat. When the thermometer gets above about 95 degrees I start melting like dropped ice cream in Phoenix in July (okay if I'm being honest its more like 90, okay 85). It's not pretty. But it can be counteracted by none other than ice cream. A delectable treat with almost mystic origins, especially when you make it yourself. How does a little ice and a little salt make it cold enough to freeze milk, sugar, and other really good stuff?

When liquid is cold enough the molecules stop moving around as much and it becomes a solid. It happens at a very exact temperature for each pure substance. The freezing temperature can be manipulated by adding something to it to create a solution. The change is known as a colligative property. When an impurity is added to a pure substance it starts to get in the way. It breaks up the bonds that creates a solid, making it harder and harder for it to freeze. Like when you are at a concert and that annoying guy at the bar is standing between you and the people you came with. This is know as freezing point depression (in a related process, when a liquid is near the boiling point the impurities cause less molecule of the pure substance to be near the surface, meaning less can escape into the gas phase making it harder to boil, this is known as boiling point elevation). When you add salt to ice the salt begins to mix in and lowering the freezing point. The ice melts. But melting requires energy, a lot of energy. When you insulate the ice from the outside it starts to take that energy from the inside container (see Marvelous Mixtures Part 4 for info on heat transfer, temperature, and energy). The inside mixture gets colder and colder and colder until it freezes. The constant stirring keeps everything inside soft, instead of a hard crystal like ice, and makes sure that the freezing occurs at an even rate. After a long time of stealing energy and stirring, tah-dah!, a delectable summer treat of ice cream, sorbet, or, my favorite, gelato!

So, I mentioned in an earlier post that I have a favorite way to eat my sweet summer peaches. The suspense is over, here is the answer. I like my peaches sliced in half with a 1/2 Tablespoon(ish) of butter, a Tablespoon(ish) of brown sugar, and a big marshmallow where the pit use to be. Wrap the whole thing in a greased piece of tin foil and throw it on a hot grill until everything is gooey and melted. Then serve it up with this cinnamon gelato. This particular gelato is very lightly flavored so if you want a little more cinnamon flavor I would add some extra ground cinnamon when you are letting everything seep.

Cinnamon Gelato

Ingredients

2 cups whole milk

1/2 cup heavy cream

4 cinnamon sticks

5 egg yolks

2/3 cup light brown sugar

1/2 teaspoon vanilla extract

1/2 teaspoon salt

Combine the milk, cream, and cinnamon sticks in a large saucepan over medium heat. Cook for several minutes, until the mixture starts to bubble around the edges. Cover, remove from heat and let set for 30 minutes. Discard cinnamon sticks. Beat yolks, brown sugar, vanilla and salt at medium speed until the mixture is thick and pale (the spatula should scoop up long ribbons that do not instantly dissolve back into the mixture). Add milk, return to sauce pan and cook over medium heat until custard thickens slightly (stir constantly). Strain through a fine mesh strainer to remove all the lumps. Chill for 4 hours - 1 day. Use an ice cream machine to freeze.

Perfectly Practiced Preservation, aka Homemade Hamburger Helper

So, I had a friend of mine ask a question about phyllo dough, why does it have to be frozen? And I started looking around for the answer. For those of you who don't know what phyllo dough is it is a dough of turkish origin, made of flour, water, oil, and either raki or white vinegar which is then rolled out until it is paper thin. It's name means leaf in greek. It is layered to make a whole slew of foods from baklava to spanakopita and is often filled with nuts, cheese or vegetables to make appetizers. It is extremely difficult to make (there are stories about whole dinning room tables full of rolled out dough), but you can buy it frozen at some supermarkets. There are a couple of reasons why it is frozen, first is to make sure that the super thin layers can withstand shipping. When a liquid dips below a certain temperature (freezing point) the molecules slow down and start sticking together to make a solid. Solids are less likely to move around in shipping, so the layers are less likely to tear. The more important reason for freezing phyllo dough is to keep it from spoiling.

Freezing and refrigeration are two natural forms of food preservation (others include drying, heat, salting, and vacuum). How freezing and refrigeration work is that all organisms, including bacteria and mold (which cause spoiling by eating the food), tend to work best at warmer temperatures. Think of a bacterium like you. When it's a nice warm spring day you are really really ready to move. You walk, skip, jump, work in the yard, whatever. But when it starts to get cold, like a Minnesota morning in ... well, October - March, you are pretty much just going to sit inside and stay warm. Bacteria and mold are the same way. If you get them cold enough they start eating slower and slower, making your food last longer. Hence freezing food to keep it fresh.

Sometimes, however, freezing isn't enough. This is where humans stepped in and invented these chemicals called ... dum, dum, dum... artificial preservatives. These chemicals work in one of three ways. 1) they create a really bad environment for bacteria to grow in. 2) The slow the oxidation of fats and lipids (aka they keep fat from breaking down into goo) or 3) They stop enzymes (natural proteins that speed up stuff like the break down of cells) from working as quickly. It all seems great, but in a large enough quantity they are really bad for the body because they disrupt the body's natural balance and can kill cells that are important for regulating the body. They can also cause tumors and cancer. Yuck.

So, in honor of avoiding these nasty little chemicals, and for nostalgia, I made Hamburger Helper not from the box (actually I was going to make an asparagus phyllo dough appetizer, but apparently phyllo dough hasn't made it to Minnesota yet, and as adventurous a baker as I am, I'm not about to attempt making this one on my own). I am happy to say it was as good as the original, not much harder, and even passed the test of a kid who's favorite food is none other than Hamburger Helper out of the box. The original recipe is from John Mastro (http://www.johnmastro.net/2009/09/cheeseburger-macaroni/), I made a couple of small tweaks, and it's better for you than the box, so eat up!

Homemade Hamburger Helper

Ingredients

1 lb lean ground beef

1 teaspoon black pepper

1 teaspoon onion powder

1/2 cup ketchup

2 3/4 cup water

1/2 lb any shaped pasta (I used penne)

2 1/2 - 3 cups shredded sharp cheddar cheese

In a large skillet with a lid, brown the hamburger and drain. Stir in the black pepper and the onion powder. Add the ketchup. Pour in the water and pasta. Bring to a boil, stirring everything together. Reduce heat to medium and cover. Simmer until the water is absorbed and the pasta is tender (~15 min if you are using penne pasta). Remove from the heat, stir in the cheese until it is all melted and even through out. Enjoy!!

(I hope to get pictures into this post eventually, but the uploader thingy is acting up, so soon)