Magic Cocoa Powder or Kitchen Science?

Why does cocoa powder refuse to mix in with milk? Alex Dainis breaks down the science of the hydrophobic and hydrophilic particles in cocoa powder in the latest Everyday Awesome. Cocoa powder is not just a simple ingredient; it's a complex mixture of various particles, some of which are hydrophobic, while others are hydrophilic. The hydrophobic particles in cocoa powder, much like oil, tend to repel water, and this is what causes them to resist blending with the milk, which is primarily water. It's a classic case of oil and water not mixing. Cocoa powder also contains hydrophilic particles, such as starch, which are water-loving and enable a thin layer of water to form atop the powder. This water layer is held together by surface tension, with each water molecule clinging to the next, creating a delicate balance. When you poke this delicate layer with a toothpick, you disrupt the surface tension, and it peels away like a popped balloon. But fear not, with the right techniques, like stirring and heating, you can overcome these challenges and successfully disperse the cocoa powder into the milk.