Paul's Cool Caramel

For my project I chose to investigate the effect of cooking time on caramel. I'd never made caramel before, but I was interested to learn about the chemical reactions that cause such simple ingredients (sugar, water, milk, and butter) to turn into something so complex and delicious.

The Science of Caramel

Before the sugar begins to react chemically and turn into caramel, there are two important physical changes that play a role in the cooking process. First, the sugar dissolves in water, and then as it begins heating up, the water begins to boil, causing the mixture to thicken and become more concentrated. The first chemical reaction is the decomposition of sucrose into the smaller sugars glucose and fructose, as shown below.

The next step is a bit more complicated, but this is where all the interesting flavors of caramel begin to form. Glucose and fructose begin breaking apart and combining together in a chaotic series of chemical reactions that produces literally hundreds of new chemical compounds. These include phenols, which have a bitter flavor, esters, which are fruity tasting, and a compound called caramelan (C₂₄H₃₆O₁₈) which gives caramel its brown color.

Early in the caramelization process

Experiment and Results

The independent variable in my experiment was the cooking time. All ingredients, amounts, temperatures, and methods were kept constant.

Recipe and Instructions

1. Set temperature to medium-high (7), place a stainless steel pot on the stovetop, and allow heat to stabilize for four minutes
2. Mix one cup sugar and 1/4 cup cold (from refrigerator) water in the pot and stir to combine
3. Cook for desired time (see results) without stirring
4. Add 1/2 cup cream. Stir to combine
5. Allow to simmer for 2.5 minutes
6. Remove pot from heat
7. Whisk in 2 tbsp. butter and 1/2 tsp. salt

Trial One - 7 minutes

This trial did not really resemble caramel. It was a very light yellow color, with a thin watery consistency. The taste was extremely sweet and was lacking the signature smell and complexity of caramel.

Trial Two - 9 minutes

This was a delicious caramel. It was a smooth, thick liquid with a nice caramel color. It solidified when cooled, but was still soft enough to spoon. It had a sweet, salty, nutty taste with a nice smell.

Trial Three - 11 minutes

This was darker in color than the other two. It solidified quickly after being removed from the heat. The taste was similar to the previous trial, but it was chewier and less sweet.

To summarize, there were three major differences to the caramel based on the cooking time. First, the caramel became darker the longer it cooked. Sugar is colorless when dissolved in water, but when the sugars began to react to produce caramelan, it begins to get its color. The longer the mixture is allowed to react, the more caramelan forms. Next, the caramel got thicker and more solidified the longer it cooked. This can be justified because throughout the process, water is evaporating. The longer the caramel is allowed to cook for, the lower the percentage of water is in the caramel. Lastly, the taste went from simple and sweet in Trial One to complex and less sweet in Trial Three. This is because the sugars like fructose and sucrose are responsible for the sweetness, and the other molecules like diacetyl and the esters give the caramel its more complex flavors and smells. The longer it cooks for, the higher the percentage of these new molecules and the less sugar you have.

Caramelization During Trial Two

End Result of Trial Two