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.
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.
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