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.
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Comments
If you like sharp cheddar, the best cheese in the world is "Cougar Gold" from WSU Creamery in eastern Washington, USA, a region not known to be a hotbed of find cheeses. It comes in a can, also not thought of as a delivery vector for a great cheese, but there you have it. Tastes great out of the can or you can age it for a few years in the refrigerator. Five or 6 years is fine. I absolutely love the crystals. No mold forms unless you open the can.
WSU's other cheeses are okay but do not stand out to me. Nothing from England or France has delivered the sharp cheddar experience like Cougar Gold.
By peterldowns 2025-10-2823:481 reply I just ordered two cans of the cougar gold, one of the viking, and one of the mild cheddar. If it's not good I will blame you.
The archaic checkout system and the fact that this is a Washington State school agricultural product make me think that this will be the best cheese I've ever eaten in my life. Quite fond of their apples!
By tomcam 2025-10-297:46 The responsibility weighs heavy on my shoulders
By fishmicrowaver 2025-10-2820:154 reply I'm not easily Influenced so I'm mystified at how canned cheese had me checking out ways to order it.
The canning process is the result of post-WW2 government funded research at WSU. It's a cool backstory for a cheese.
By tomcam 2025-10-2821:38 Had no idea! Love this! The website looks like it dates from WWII tbh
By supportengineer 2025-10-2821:581 reply Yeah I just ordered one. The effectiveness of this HN post plus this parent comment has me convinced they're in cahoots.
By tomcam 2025-10-2821:39 I knew you had it in you
By Wingman4l7 2025-10-293:28 Not the first time I've seen it organically recommended, and I'm not surprised. A buddy has some of this stuff, he usually ages it for a minimum of a year, ideally 2+, in the fridge. Will sometimes have fantastic crystals, and even if it doesn't it's still exceptional sharp cheddar.
By PeterHolzwarth 2025-10-291:58 The well known Rainier cherry cultivar similarly comes from Washington State University - quite an ag program they have there!
By omnicognate 2025-10-2822:101 reply I'd love to try that but the only site I can see selling it here in the UK wants 85 quid a tin.
There are plenty of extra mature cheddars with crystals here, though. Marks & Spencer have a 2 year aged one called Cornish Cruncher that I'm partial to.
By omnicognate 2025-10-297:05 Indeed, including a cave aged one actually made in Cheddar (which is amazing). Godminster and Black Bomber are both very nice, and are wax sealed so might be similar to the canned stuff. And that's before you get into the unpasteurised stuff you're not even allowed to sell in the states. (Edit: I'm wrong about that - you can if it's aged more than 60 days.)
I'd really like to try this Cougar Gold, though. People get nationalistic about cheese, but good is good wherever it's made. If England can have the best brie I know of (Baron Bigod) there's no reason in principle the US couldn't have the best cheddar. Canada makes rather nice cheddar too, which you can buy in UK supermarkets.
The US terminology is odd, though. Sharp isn't how I'd characterise most extra mature cheddar.
By ndsipa_pomu 2025-10-290:07 Davidstow Reserve - matured for 36 months.
By msuniverse2026 2025-10-2820:481 reply I remember hearing about that cheese in the past. Does it need a cold chain to be shipped overseas?
Not sure what a "cold chain" is but yes, it's shipped ice-filled styrofoam containers. Without it the cheese would sweat, which freaks people out.
By SideburnsOfDoom 2025-10-299:00 > Not sure what a "cold chain" is
Why do you choose that over looking it up? https://en.wikipedia.org/wiki/Cold_chain
By tbrownaw 2025-10-2823:48 "chain" as in "supply chain".
By TheAmazingRace 2025-10-2822:28 I'll be making a stop in Seattle here in a few weeks. I'll see if this is available for purchase at Haggen.
Some guy cracked open a 15 year old can of Cougar Gold and said it was good: https://www.reddit.com/r/Cheese/comments/1oas900/update_i_op...
By foofoo12 2025-10-290:07 We once popped open a bottle of red wine from 1968. After tasting, we figured it was probably the best before date.
By ndsipa_pomu 2025-10-290:072 reply Hmmm, I'm somewhat doubtful about cheese from the USA as my experience there (only on holiday, mind) was that most cheese seems to be made of plastic. However, I fully acknowledge my lack of knowledge about good/great american cheeses and I'm sure there are small scale producers of quality products.
Some of the best cheddars that I've tried are Wyke Farms Cheddar (from Somerset, but not quite in Cheddar itself) and my favourite is Davidstow which comes from Cornwall. Quite why you'd be expecting quality Cheddar cheese from France is beyond me - wouldn't they consider it insulting to be making an English style cheese when they have so very many unique types of French cheese?
By technothrasher 2025-10-291:50 Most of the mainstream cheese that you're going to encounter here in the US is boring and tasteless. Even most of the cheddar we get imported from the UK is terribly mediocre, I've found. It's just what many American's like, apparently. But that doesn't mean you can't get good cheese, both domestic and imported, if you frequent a specialist local cheese shop. There are quite a few farms in Vermont and New Hampshire, and also a couple in Massachusetts, that I've found make really good cheddars, rivaling some of my favorite Somerset cheddars. I'm sure there are good producers outside of New England too, I just know those ones as that's where I am.
Isn't McDonalds massively successful in Paris? Here's one artisanal creamery in the US: https://www.cascadiacreamery.com/photo_gallery.html
There are hundreds of these across the country, but you have to seek them out. You can also get raw milk cheeses in the US.
By ndsipa_pomu 2025-10-299:35 Those certainly look like proper, tasty cheeses.
I don't doubt that there's a thriving junk food culture in France, but they do have something like 1000 different varieties of cheese, so I can imagine the french getting annoyed if someone asks them for a nice bit of cheddar.
The U.S. seems to have a strange relationship with raw milk - I believe it can be fairly freely sold over there, whereas we in the UK can't buy/sell raw milk in shops although it can be purchased from farms and farmer's markets. Meanwhile, raw milk cheese are common in supermarkets - they just put a label on it warning pregnant women and people with compromised immune systems.
I enjoyed reading the article, but really wish it had photos to help educate the reader on how to distinguish between crystals and mold.
Totally agree - interesting info but nothing of practical use, especially because white spots can be mold.
See https://www.eatortoss.com/how-to-tell-if-white-stuff-on-chee..., https://www.eatortoss.com/aged-cheddar-with-a-crusty-white-s....
By bfkwlfkjf 2025-10-298:31 To my untrained eye: not sure about the first one,but the second one is obviously good. Correct?
By the__alchemist 2025-10-2819:55 This is a bit confusing: "The crystals are soft, white, and sometimes appear damp."
The rule of thumb I've heard is hard white: crystal. Soft white: mold.
If you can't tell, I would dump it.
By bigiain 2025-10-2822:31 There's a bunch of broken images there (at least I see them in Safari).
Sadly, the wayback machine has snapshots of the article going back to 2020, but doesn't seem to have archived those broken image links.
> 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%.
Yogurt-making produces a lot of whey too, though probably closer to ~50% whey rather than 90% (when made at home). The only difference between greek yogurt and regular yogurt is that greek yogurt is strained to remove the whey, making it thicker / creamier. Though most commercial brands try to cheat and thicken it with something like pectin (which usually makes it kind of jello-y).
Anyways all that to say my favorite yogurt is the one where the only ingredient is milk + yogurt culture. No thickeners, added sugars, flavoring, I like to add those myself.
By FuriouslyAdrift 2025-10-2821:041 reply Whey goes to make protein powder, whey butter, animal feed, etc. The Ag industry is so competitive that usually every little bit gets used for something.
By carlob 2025-10-298:01 And ricotta, how can you forget ricotta!
By kragen 2025-10-2822:19 I usually make my yogurt with powdered milk so that I can have less water in it. I don't add thickeners or sugar.
By colechristensen 2025-10-290:25 >> That’s right: if you run the numbers on cheese manufacturing, the percent yield is only about 10%.
Percent yield is an odd choice of words when the "waste" product is 90-95% water.
