The Science Behind Hot Chocolate

The holidays are approaching, and it’s cold outside. As temperatures drop during the winter season, students rush through crowded hallways and across the bridge for warmth to combat the cold. Their solution: hot chocolate. It’s so popular that both youths and adults line up outside cafes, Starbucks, and Dunkin’ Donuts, in freezing temperatures, just to get a cup. However, they don’t actually need to face these long lines for something so simple. Hot chocolate can be made right at home, and the delicious mixtures found in the warm mug are more interesting than they look.

When cocoa powder is initially mixed with hot water, a physical reaction occurs, turning the solid chocolate powder into liquid. Chocolate, or cocoa, powder is composed of fine cocoa bean particles called cocoa solids. These particles are naturally coated in cocoa butter, which creates a fatty outer layer. As a result, the powder is hydrophobic, or unwilling to dissolve in water. Hence, when water is initially poured onto the powder, the cocoa powder sits on top and forms small lumps instead of dissolving immediately. As the cocoa is stirred, the particles remain suspended in the liquid, forming a colloidal suspension. Many commercial hot chocolate mixes contain emulsifiers, such as mono- and diglycerides, which work by coating the cocoa particles, helping them remain evenly dispersed in water and preventing the mixture from separating. These processes together give hot chocolate its rich, smooth texture and consistent flavor.

Another factor that explains cocoa powder’s behavior with water is alkalization, a chemical process used on cocoa beans or cocoa powder to reduce its natural acidity. When cocoa beans are first extracted, they have a very bitter taste, so they are treated with an alkaline substance—commonly potassium carbonate—that neutralizes its acidity by raising its pH level. This process not only helps the powder dissolve in water, but also changes the flavor of the cocoa. Neutralization reduces the concentration of free hydrogen ions, lowering the perceived acidity. Alkalized cocoa tastes smoother and milder, which is why most types of hot chocolate have such a rich and mellow taste.

Beyond its comforting taste, hot chocolate contains certain chemicals that make us crave it—a craving that grows throughout the seasons, especially in the winter. For instance, cocoa powder naturally contains theobromine, which is known as a mild caffeine stimulant. Since this chemical contains small amounts of caffeine, studies show improvements in mood and alertness when ingested. Combined with the warm temperatures of the liquid, theobromine enhances the cozy feeling we associate with hot chocolate and winter. Additionally, cocoa is rich in flavonoids, which are natural plant compounds known for its anti-inflammatory effects, such as improving blood flow and lowering blood pressure. Since its natural chemical structure allows them to act as a defense mechanism against pests, flavonoids are naturally bitter and contribute to the bitter taste of hot chocolate. 

Hot chocolate provides us with a sense of psychological comfort. Humans naturally associate warmth with comfort, and holding a warm cup of hot chocolate can make people feel more comfortable and relaxed. The heat from the drink can raise body temperature, signaling the brain to release neurotransmitters like endorphins, serotonin, and dopamine. These hormones are nicknamed “feel-good hormones” because they produce happy and euphoric feelings. As hot chocolate is often referred to as a common childhood and holiday drink, the rich aroma and smooth texture can also stimulate our senses, bringing back feelings of nostalgia and contentment.

So the next time you worry about hot chocolate being unhealthy, just remember the health benefits it can provide and enjoy that cozy treat without guilt! In an environment like Stuy, a warm cup after a long day of classes and homework can be the perfect way to relax and recharge.