These white crystals are badges of savory cheese honor

White crystals are common on certain types of aged cheeses; don't confuse them with mold!

What you see: White dots in your aged Italian-style or gouda cheeses that are clearly not mold What it is: Crystals of an amino acid called tyrosine Eat or toss: Eat! If an aged cheese and a textured mouthfeel are what you’re looking for, you may even want to count your lucky cheese crystals!

The story: Let’s get microbial for a minute:

- The white specks in the image above are not mold or anything harmful - They are connected to the microbial processes essential to cheese making

As we know, microbes help transform milk into rich, creamy, zesty, sweet, salty, melty amazingness. Cheesemakers rely on different microbes that each have their own styles of munching on the various components of milk, which helps create the wonderful cheese diversity we know and love.

In making aged Italian, Dutch, Swiss and some other cheeses, a bacterial culture called lactobacillus helveticus is added to help spur the development of flavor. This L. helveticus character is particularly good at breaking the milk’s protein chains into free range amino acids.

As the cheese ages, the L. helveticus’s amino acid work product, tyrosine, accumulates. Tyrosine dissolves in water, but cheese loses moisture as it ages, so there's not much for the tyrosine to dissolve into. When, In the body of the cheese, the tyrosine finds other tyrosine they tend to clump together. When enough bits of tyrosine are partying, you see little white crystal-y clusters and your mouth detects a delicate crunchy melt.

We’re all pretty happy about this because that crunch improves mouthfeel. As far as its taste goes, interestingly tyrosine has been variously described as adding bitterness, imparting some umami depth or having no flavor at all. The primary reason tyrosine is considered a sign of quality is not its own characteristics as much as that it's evidence of a long and deliberate, and, dare we say, beautiful, aging process.

This post is going to end here because I suddenly need to sink my teeth into some fantastically aged, wonderfully textured, tyrosine-riddled gouda.

But, before I go, one more thing to keep in mind—tyrosine crystals tend to be visible as dots on cut surfaces inside the cheese or inside those little air pockets that look like "eyes"; you're less likely to see them on the outside. Stay tuned for future posts about the other types of harmless crystals you may see assembled on your cheese’s surface. Also check out the Cheese Science Toolkit, which gets into more detail and has a great infographic.


Patrick Polowsky. Food scientist and author of Cheese Science Toolkit.

Microbes 101. Cheese Science Toolkit. Patrick Polowsky.

Cheese Crystals. Cheese Science Toolkit. Patrick Polowsky.

Detection and enumeration of Lactobacillus helveticus in dairy products. International Dairy Journal. Volume 68. May 20017. P. 52-29. Aline Moser, Hélène Berthoud, Elisabeth Eugster, LeoMeile, StefanIrmler “Proteolysis,” Merriam-Webster. Global Cheesemaking Technology: Cheese Quality and Characteristics. Edited by Photis Papademas, Thomas Bintsis. P. 53.

Umami makes you say ‘Ummm.’” Sun Sentinel. November 1, 2001. By Shirley O. Corriher. The Cheesemonger: A Bit of Crunch in Your Cheese? Nora Singley. Apr 15, 2008. The Kitchn

Crystallization in Cheese. The Dairy Pipeline. Wisconsin Center for Dairy Research. Mark Johnson. Volume 26 Number 3, 2014.

Crystals Are a Cheese’s Best Friend. Jamie Ditaranto Culture November 18, 2014On Food and Cooking: The Science and Lore of the Kitchen. Harold McGee. p. 63. Serious Cheese: Know Your Microbes. Jake Lahne. Serious Eats Cheese 101: Hard Facts About Hard Cheese. Liz Thorpe. Serious Eats

Exploring Cheese Crystals. Cheese Underground. Nov. 12, 2014. What are the crunchy crystals in cheese? Garrett McCord. Epicurious. Nov. 30, 2011. It’s all about the crystals! Castello Cheese. Sept. 29, 2014.

Say crystals!

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