Cheese Crystals

Cheese Crystals

White spots are good: are you throwing away a perfectly good cheese?

The  funny thing about being a food scientist, is that before meeting me,  most people have never even heard of my field. Yet, almost  instantaneously after pleasantries, I am bombarded with any, and every  food-related question they’ve ever had. My phone has become an emergency  helpline for all food-related inquiries.

I’m  pretty certain I spend 50% of my day answering questions from family or  friends on whether or not food is safe to eat. There was a call from an  old roommate who hard boiled eggs at night, forgot about them, and only  put them in the refrigerator when she realized her mistake the next  morning.

A  countless number of questions about meat being safe to eat after  sitting out at room temperature. Is it safe if it was only sitting out  for two hours? Four hours? Overnight‽ Please, I beg you, stop leaving  meat out on the counter! My advice is to never chance it with  questionable meat. Risking your health is just not worth it, unless you  enjoy nausea and explosive diarrhoea.

There  is however, one mistake I see people make over and over again: throwing  out perfectly delicious cheese that they mistake has mould growth. As a  Wisconsinite, this just breaks my cheese-clogged heart, so let me  introduce you to crystallization in cheese.


If  you are an avid cheese-monger or turophile, you may be familiar with  the appearance of white crystals on the surface or interior of your  cheese. Tiny, pin-head size bumps that appear out of nowhere, or longer  ones that develop into one continuous smear of white.

To  cheese experts, the crystals symbolize a high-quality cheese, aged to  develop a full-bodied flavour. But to consumers, the white bumps can be  mistaken for mould and yeast growth. They often think of them as a  defect or a spoilage, rather than a sign that the cheese is actually  better.

The  truth is, the harmless crystals are a natural part of ageing cheese.  When people throw them away thinking they’re spoilt, they end up with a  lot of unnecessary food wastage.


Actually, all cheese making produces quite a bit of wastage. On average, if a dairy  starts with ten-thousand pounds of milk, they’ll end up with only a  thousand pounds of cheese. The remaining nine-thousand pounds ends up as  whey while the curd is formed.

That’s right: if you run the numbers on cheese manufacturing, the percent yield is only about 10%.

Even  more mind-blowing is the fact that, only a couple decades ago most  dairies didn’t do anything with the whey. They just chucked it into  water sources, completely devastating any wildlife in the process. If  you look at the location of most dairies, especially older ones, you’ll  notice they were built right next to a river or lake — and now you know  why.

Luckily,  dumping is now illegal in most places. This has forced the dairy  industry to find a use for their by-product, which is why “whey protein  powder” has exploded in popularity. Dairy chemists realized that the  liquid whey was an excellent source of protein, and can be dried into a  powder.

So,  all you whey-protein guzzling bodybuilders can thank cheese for  providing your muscle-making powder. But, let’s get back to the  crystals.


I’ll  never forget the day one of my roommates was angrily stomping around  our shared kitchen. Afraid something was wrong, I went to investigate. I  found her just about to toss out over half a block of cheese in order  to “save” the rest from mould growth.

She  went on to complain how she had just bought the cheese, so I had my  suspicions about the “spoilage.” I asked to have a look, and sure  enough, it was just calcium lactate crystals forming on one side.

This  is quite understandable. Often, crystals end up looking like yeast or  mold growth, which of course you should definitely not be eating. But if  you’ve recently purchased your cheese, as well as properly handled and  stored it, I wouldn’t worry about spoilage.

My  roommate likely didn’t tightly seal the product after the first  opening. Loose packaging allows for increased exposure to air and a spot  for moisture to accumulate, which helps the crystals form.

There  are many kinds of cheese-crystals, but the two most common ones are  formed by ‘calcium lactate’ and ‘tyrosine’. Both these crystals are the  result of bacterial activity, but they’re not at all dangerous.


Have  you ever noticed a burning in your joints, after a heavy round of  exercise? That’s the feeling of ‘lactic acid’ building up.

There  are two ways your body can convert its stored up reserves to energy:  with oxygen, or without. The with-oxygen version is much more efficient,  but it needs oxygen to run — and when you’re doing a lot of heavy  exercise, that oxygen starts to run short.

That’s  when your body switches to the oxygen-free process, ‘anaerobic  respiration’, which releases lactic acid as a by-product. Lactic acid is  what builds up near your muscles to give the burning feeling. But don’t  worry — it’ll get released later, when oxygen comes in, turning into  harmless carbon-dioxide and water.

Incidentally, lactic acid is also part of what forms the calcium-lactate crystals in cheese.


Cheese,  as you know, is made using “starter culture”. That’s basically a bunch  of bacteria that help the milk ferment. The bacteria metabolise in a  similar anaerobic way, converting sugars in their bodies to energy, and  releasing lactic acid as a by-product.

In  cheese, lactic acid doesn’t go away or turn into water. It sticks  around. And, when it gets in touch with calcium, which is naturally  present in cheese, the two combine to form calcium-lactate crystals.

Calcium  lactate crystals are the most commonly encountered crystal in cheese.  They are often found in aged cheddar, parmesan, and gouda, where you can  see them as long, white streaks or smears along the surface.

If  the cheese is not tightly packaged, or carefully resealed after  opening, you will likely see calcium lactate crystals aggregate in this  area. The crystals are soft, white, and sometimes appear damp.

So  if you see these crystals, it doesn’t mean the cheese has gone bad. On  the contrary, the cheese is now even better than before, because the  crystals add a unique texture to the cheese!


Apart  from lactic-acid crystals, ‘tyrosine’ crystals are the other common  type. You may see them as discrete white dots. Each the size of a  needle-point, a bright white in colour, and leaving a gritty mouthfeel,  they usually come on the inside of hard Italian, Dutch and Swiss  Cheeses.

The surface of an aged gouda with long streaks of crystals formed from calcium lactate and individual, pin-sized crystals formed from tyrosine.

Tyrosine crystals are usually linked to the presence of a bacterium named Lactobacillus helveticus, or L. helveticus for short. Cheese makers like to use this bacteriumsince it gives their cheese a unique flavour.

The catch is, L. helveticus has  enzymes that breakdown proteins, which release amino-acids like  tyrosine. Those enzymes are so efficient, they generate many more amino  acids than the bacteria need to survive. They leave extra tyrosine lying  around — and there come the crystals.


Alarmed  that my roommate was about to waste her food and money, I polled the  seven other people who also lived in our house. I was disappointed to  find out they all identified the white markings on the cheese as  microbial growth, not crystals. They were in agreement that the cheese  was spoiled.

As  a food scientist, such situations fuel my belief that we need more  science articles to be expressed in layman’s terms. (On the positive —  though selfish — side, the situations also provide me with excellent  ideas for my next writing piece).

Cheese  crystals may seem visually unappealing at first, but over time, you may  find yourself looking forward to them. They are completely harmless and  provide a crunchy, alternative texture to the cheese.

Soon  enough, you’ll start seeing those white streaks and bumps not as a  blemishment, but as an indicator of a good, finely-aged cheese.


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