What Causes Cheese to Melt?

What Causes Cheese to Melt?

Melting cheese is the key principle in many dishes such as pizza, lasagne and mac and cheese, and many more.
In this article, we look at what causes cheese to melt, in addition to some examples of the best melting cheeses, as well as the worst melting cheeses, and why this is.

What Causes Cheese to Melt?

Cheese melts best when there is a good balance between fat and moisture content. When the cheese begins to heat, at around 32℃, the solid milk fats in the cheese liquefy and the cheese starts to soften. The fats then rise to the surface, giving it a greasy like texture.
As the cheese continues to heat, the bonds between the proteins eventually collapse, better known as melting.

This collapsing (or melting) occurs at different stages depending on the type of cheese. For soft and young cheese (for example mozzarella) it may be around 55℃. Semi-hard cheese (such as cheddar) will melt at 65℃. Hard cheese (like parmesan) will melt even higher at approx 82℃.

Factors which Cause Cheese to Melt:

The Moisture Content:

Soft cheese tends to have a higher moisture content, allowing the cheese to flow much more freely in comparison to dry, hard cheese.
Soft cheese proteins are more loosely packed together, allowing lots of water to sit in between the proteins. This ensures the cheese melts at a lower temperature. This of course is the opposite for very dry, hard cheese.

Age of the Cheese:

A glue-like substance binds the calcium proteins with the casein molecules that are in the cheese.
If the cheese is young and fresh, the casein molecules are large and very stretchy, which is why cheeses such as mozzarella are very stringy when melted.
As cheese ages, the enzymes that allow the cheese to ripen are present and attack the casein molecules. This causes them to break down into smaller pieces. As a result, the cheese flows more smoothly as it melts.

Fat Content and Acidity:

Cheese with high-fat content is also good for melting. Cheese with a high acidity level such as mozzarella or Emmental becomes stringy once melted.

what causes cheese to melt
Mozzarella becomes stringy when melted.

The cheese will melt best when curd mixes with animal rennet during the cheese-making process.
If the curds are mixed with acid during production (common in fresh cheese such as halloumi and ricotta, etc) they will not melt at all. This is because the acid dissolves the calcium glue holding the cheese together. When the cheese heats up, moisture releases as the protein bonds tighten themselves together. As a result, there is not enough moisture in the cheese to help it melt and therefore it will solidify.
This type of cheese is great for cooking on the BBQ or grill because it will not melt and make a mess!

Read more here on cheese that is great for melting.