Chemists in the Kitchen: Aromatics and Ring Structures: Caramel

Caramel is made from sugar, but though the basic elements are the same in each substance, the flavor, texture, and smells of each are entirely unique. This is because regular sugar, or sucrose, must undergo a chemical reaction before it becomes the gooey goodness we call caramel.

Now, before we continue, a quick word about chemical reactions... they only occur when bonds are broken or made. There is a difference between physical and chemical changes: chemical changes restructure the configuration of atoms while physical changes do not. For example, dissolving sugar in water only disperses the same molecules in water, it does not change the molecules themselves. However, caramelizing sugar rearranges the molecules and breaks them down, forming new molecules. The reaction is as follows complicated but involves the sucrose molecules breaking down into fructose and glucose, and eventually forming into new rings and aromatics. This all occurs with the addition of heat, and it is a temperamental process.

Here is a pictoral representation of the carbon rings in both sugar...

and caramel...

To make caramel, recipes begin with either the wet method (combining sugar, water and a crystal inhibitor and then boiling) or the dry method (melting dry sugar and then adding other ingredients). I prefer the more testy dry method because it is easier to gauge doneness and draw out a real caramelized flavor, but the wet method is often 'safer' in that it leaves less room for error. We will focus on the dry method for the sake of its obvious chemical transformation.

To start, place the sugar and water in a large saucepan and begin heating, stirring occasionally. After some time it is evident that the sugar is melting (caramelizing), shown by the sticky residue that coats the bottom of the pan. Though it may take a while, let the caramel cook until it is a uniform, thick, smooth amber color. At this point, the chemical reaction has occurred, and the aromatic rings should be tantalizing your nose with nutty--but not burnt!-- caramel smells. Now the going gets tough.

After caramelization, crystallization becomes the primary issue. This is when sugar crystals begin to form in the caramel, creating a grainy texture. To avoid this, don't allow any "seed crystals" of sugar into the caramel. Seed crystals are pieces of sugar that would provide opportunities for other sugar molecules to latch on, ruining the silky caramel goodness. Adding an anti-crystallization agent, such as honey or corn syrup, interferes with these molecules latching on to one another and thus helps as well. We used honey in our caramel. It also added a dimension of flavor.

When the caramelized sugar is prepared, add in the butter and other ingredients, stirring constantly. The caramel may seize for a minute, but continued stirring will smooth things out. At this point, the mixture should be stirred as it cools to keep it uniform and delicious. Whisking it while submerged in an ice bath works marvelously.