Why doesn’t halloumi melt?

When you think of cheese, one of the first things that likely pops into your mind is the image of something smothered or stuffed with melted cheese, like pizza or raclette. Most cheeses soften when you apply heat, but a few such as halloumi and Indian paneer stubbornly refuse to melt. What’s up with these cheeses? Gianaclis Caldwell, author of Mastering Artisan Cheesemaking, explains the phenomenon of non-melting cheese. 

Caldwell discusses the science behind cheeses like queso fresco, halloumi, and Lithuanian white cheese, which all remain solid when heated. Whether or not a cheese melts comes down to the networks of protein found in each type. Caldwell says that in order to “ooze or stretch, a cheese must have a flexible network of proteins – created by rennet and loosely held together by calcium phosphate – with just enough give that, when heated, they can move and reform. (Kind of like your favorite pair of skinny jeans.) At the other end of the spectrum, a cheese that remains intact and doesn’t melt on the grill has a rigid structure with no yield.”

There are two basic ways to make a non-melting cheese: by using an acid such as lemon juice or vinegar in combination with high heat (paneer, queso fresco), and by using rennet but halting the normal process (halloumi). In the former method, the combination of high heat and acid causes whey proteins to stick to the cheese proteins (aka casein). Pressing or weighting the cheese multiplies this stickiness, resulting in a dense, rigid cheese.

With halloumi, the process is different. A hot “bath” in whey prevents the development of additional acid, which means that the calcium phosphate, necessary for the loose structure described above, is expelled from the cheese. This creates a rigid protein network, resulting in a non-melting cheese that is perfect for high-heat applications like grilling or frying. 

Photo of Grilled halloumi and mango slaw with coconut tahini dressing from Ready, Steady, Glow by Madeleine Shaw