The Chemistry of Caramel

Close your eyes and imagine the sweet taste of caramel. Whether it be caramel sauce, chewy caramel, or toffee, the idea of that sweet candy can make anyone’s mouth water. But did you know how much chemistry goes into making caramel? Read on to find out!

Yummy caramel!

Caramelization consists of chemical reactions that can be very complicated, and some of these reactions are not yet entirely understood. It produces hundreds of chemicals! In this blog post, we will try to create a comprehensive view of the information we know about caramelization so far.

When we make caramel, whether as a candy or for a filling or topping on other food, we use sugar, butter, and water. Sugar is the main component we want to focus on. A small amount of water is added to sugar, sucrose, with addition of heat, and the sucrose breaks down into two simpler sugars, glucose and fructose.

Sugar

C12H22O11 (sucrose) + H2O (water) + heat —> C6H12O6 (glucose) + C6H12O6 (fructose)

This reaction, simplified into a chemical reaction above, is called sucrose inversion. The next step in caramelization starts off with the glucose and fructose, which are in solution (in water). These two molecules go through dehydration as the molecules are bonded together while giving off water. The hydroxyl group of one molecule and the hydrogen of the other combine together and leave as water, leaving these two molecules connected. This dehydration, also known as condensation, takes place with many of the glucose and fructose molecules. However, the products are not always the same, as the reaction can happen with any hydroxyl group within each molecule and any hydrogen ion within each molecule. The possibilities are endless. Additionally, the products vary even more because they begin rearranging themselves, creating many different isomers.

The above caramelization procedure was the procedure of making caramel from sucrose. The caramelization of other sugars, including fructose, galactose, glucose, and maltose, differ in the amount of heat necessary for the reaction to occur. Caramel’s taste can be attributed to the different compounds produced within the caramelization reactions, along with sweet sugars. For example, diacetyl is formed in the beginning of caramelization, and gives caramel a buttery, butterscotch-like flavor. Different compounds such as esters can give off rum flavors, while furans taste like nuts.

Many different types of sugars

The Maillard reaction is considered very similar to caramelization, but caramelization happens at a higher temperature, and is a reaction of sugar with itself. However, the Maillard reaction occurs with sugar and protein. Though both procedures include the dehydration synthesis, the Maillard reaction incorporates an amino acid from a protein and happens at a lower temperature. Many people may consider the Maillard reaction and caramelization to be the same thing, but they are slightly different from each other, so make sure not to get them confused!

Maillard reaction

Although the exact date of the discovery of caramel is not known, many believe that the Arabs were the first to consume sweet caramelized sugar, around 1000 AD. The caramel they knew, however, was the hard and crunchy kind that we know today as toffee. Around the 1850s, people began adding milk and fat to their recipes to create chewy caramel. However, caramel (including toffee and soft caramel) wasn’t nearly as popular at that time as it is today. This all changed when the Hershey company began adding caramel into its candies, creating the “Lancaster Caramel Company” – people began to love caramel much more. Because of Hershey, caramel is now a well known candy that comes in all shapes and sizes. Who knew a discovery over a thousand years ago would lead to a tasty treat that involves lots of chemistry to make it!

 A video showing how three different types of caramel is made!

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