What happens when you boil sugar?

Answered by Jesse Garza

When sugar is boiled, an interesting chemical reaction takes place. The heat causes the molecules within the sugar solution to gain energy and become more active. This increased energy allows the water molecules to break free from their bonds and escape into the air as vapor. As a result, the water in the sugar solution evaporates, leaving behind the sugar molecules.

However, the process of boiling sugar is not as simple as just removing the water. As the sugar molecules are heated, they also undergo a series of complex changes. The carbon, oxygen, and hydrogen atoms in the sugar molecules start to evaporate as various organic components. This transformation is known as thermal decomposition or pyrolysis.

During pyrolysis, the heat causes the sugar molecules to break down into smaller molecules, such as caramel and other compounds. These smaller molecules are responsible for the darkening and browning of the sugar. The longer the sugar is boiled, the more intense the browning becomes, eventually leading to a charred and form of sugar.

The exact composition of the organic components formed during the pyrolysis of sugar can vary depending on factors such as temperature and duration of boiling. However, some common compounds produced include caramel, hydroxymethylfurfural, and various volatile organic compounds.

The caramelization process gives the sugar a rich and complex flavor, which is why caramel is often used in desserts and confectionery. However, when sugar is boiled for too long or at high temperatures, the caramelization can go too far, resulting in a burnt or charred taste that is unpleasant.

In my experience as a sommelier and brewer, I have encountered the effects of boiling sugar in various culinary and processes. For example, when making caramel sauce or caramelizing sugar for flambéed desserts, it is crucial to monitor the boiling process carefully to achieve the desired level of caramelization without burning the sugar.

Similarly, in brewing, sugar is often added to the boil to provide fermentable sugars for the to convert into . However, if the sugar is boiled for too long or at too high a temperature, it can lead to undesirable flavors in the final , such as a burnt or harsh taste.

When sugar is boiled, the water evaporates, leaving behind the sugar molecules. However, the heat also causes the sugar molecules to undergo pyrolysis, resulting in the formation of various organic components and the darkening of the sugar. The longer the boiling process, the more intense the browning and charring of the sugar become, leading to a bitter and charred taste. Careful monitoring of the boiling process is essential to achieve the desired level of caramelization without burning the sugar.