What are those crunchy bits in my cheese?

What are those crunchy bits in my cheese?

The quick answer is not salt.
Bear with us for the longer, slightly more scientific answer.


Milk, on average, is 3-4% protein and we all know that cheese is made from lots of milk. While the exact amount of protein varies with each style of cheese, harder cheese such as Gruyère and Parmigiano Reggiano can contain 30% protein.

These proteins naturally break down as cheese ages and under certain circumstances form particular amino acids (mostly Tyrosine and occasionally Leucine). The formation of Tyrosine seems to be linked to the activity of a culture called Lactobacillus helveticus, which is added to cheese during production to encourage the development of flavour.

These amino acids then join together over time and form tiny crystalline structures. You’ll often see these crystals on the cut surface of a cheese, most often in the ‘eyes’ which can develop in certain Alpine-style cheeses. Sometimes, you’ll be able to perceive these crystals as a ‘grit’ in the cheese but not necessarily be able to see them.

The pleasant crunch of these crystals contribute predominantly to the texture as opposed to the flavour of the cheese. That said, the cheeses in which they are found tend to by virtue of age be fuller in flavour and on the saltier end of the spectrum.


There is another crystal you may come across which is different altogether. Occurring predominantly on the exterior of cheese such as aged Cheddars, these crystals are the calcium salt of lactic acid.

As the cheese ages, cultures break down the lactose in the cheese, producing lactic acid. As the lactic acid rises to the surface it can bind with calcium ions and form calcium lactate, eventually becoming visible as crystals.


Under particular acidity conditions, calcium and phosphorus can crystallise to form calcium phosphate crystals. They are less common but occasionally found on bloomy rinds (white moulds, washed rinds and some blue cheeses). 


Naturally occurring surface microbes on washed rind cheese lead to the formation of these ‘gritty’ crystals. 

Here’s a handy little infographic if you want to wow your guests during the cheese course.

Want to experience crystals first hand? Try these cheeses.

L'Amuse Signature Gouda

Swiss Gruyère Vieux AOC

Marcel Petite Comte ‘aged’

Cornish Kern

Parmigiano Reggiano 

By Olivia Sutton