The Scientific Reason Mozzarella Makes The Perfect Melted Cheese

Your favorite pizza, empanada, or lasagna all have one thing in common — delicious, stringy, melted mozzarella that makes every bite irresistible. The cheese is high in both casein and fat. Casein, a protein, is responsible for this ooey gooey goodness. Fat content also plays an essential role in whether or not you'll get perfectly melted, stretchy mozzarella. These two components, plus water, form a casein matrix that binds calcium, fat, and water together, allowing for the structure to be flexible and fluid. At ideal temperatures, between 86 degrees Fahrenheit and 113 degrees Fahrenheit, the fat heats up and moves from a solid structure to a liquid structure, breaking some of the calcium bonds, which allows the cheese, in this case, mozzarella, to flow, stretch, and melt. Acid also plays a crucial role in the matrix bonds — too much acid and the bonds will break; too much acid and they'll never melt.

This is why it is so difficult to replicate the same sensory characteristics in dairy-free cheese, as a casein matrix can only be found in dairy milk. Vegan cheeses are often softer and more pliable from the start, as they lack a casein matrix that contributes to their rigidity, which holds the fat so it doesn't seep out and become oily in dairy cheese.

Mozzarella, the lightly salted, soft cheese known for its stretchability, originated in Italy and was first created using the milk from water buffalo, sometimes referred to as buffalo mozzarella. But, now popular all across Europe and the United States, with Americans ranking it their favorite cheese, per Economic Research Service, it's much more common to see cow's milk mozzarella, known as fior di latte mozzarella. Cow's milk mozzarella, usually made from whole milk, comes in many forms: Appearing in logs, large homemade balls, and tiny spheres across the grocery store shelves. Fresh mozzarella is the creamier and meltier counterpart to low-moisture mozzarella, also known as part-skim mozzarella or processed mozzarella, which is often shredded. When melted, fresh and homemade mozzarella might release water, which is normal. Part-skim mozzarella has a lower fat content and a firmer texture, and while it may not melt as loosely, it does provide a nice, bubbly brown top for your favorite foods.

This also explains why other cheeses, such as Swiss and feta, retain their structure when heated at high temperatures — they either have too much calcium or not enough fat to produce a stretchy, melty product. Conversely, if there is not enough calcium, they will likely produce a looser cheese from the start, such as ricotta.