If you have ever opened a box of cheese and immediately thought, “Why does this smell like feet?”, you are not alone. This is one of the most common reactions people have to washed rind cheeses.

And here’s the uncomfortable truth. Some cheeses really do smell like feet — not metaphorically, but biologically.

The same families of bacteria responsible for human foot odour are also central to the aroma of many famous cheeses. That overlap is not an accident. It is the result of fermentation, microbial ecology, and centuries of cheesemaking knowledge.

Once you understand what is happening on the rind, the smell stops being gross and starts being fascinating.

The unexpected connection between cheese and human skin

Feet do not smell because of sweat alone. Sweat itself is mostly odourless.

The smell appears when bacteria living on the skin metabolise compounds in sweat and release volatile aroma molecules. These include sulphur compounds and short-chain fatty acids that our noses are extremely sensitive to.

Cheese rinds, especially washed rinds, create a very similar environment. They are warm, moist, slightly salty, and rich in nutrients. In other words, they are perfect homes for certain bacteria.

That similarity is the reason the aromas overlap so closely.

The real star of the show: Brevibacterium aurantiacum

For a long time, Brevibacterium linens was credited as the main cause of foot-like cheese aromas. More recent microbiological studies, however, show that Brevibacterium aurantiacum is far more commonly dominant on washed rind cheeses.

This distinction matters.
B. aurantiacum is not just present — it thrives during cheese ageing.

It is exceptionally good at breaking down proteins and fats at the surface of the cheese. In doing so, it produces sulphur-containing compounds and fatty acids that closely resemble the molecules responsible for human foot odour.

The chemistry is strikingly similar, even though the context is very different.

Why cheesemakers want these bacteria in the first place

It is important to be clear about one thing. This is not contamination.

Cheesemakers intentionally create conditions that allow bacteria like B. aurantiacum to grow. These microbes are essential to flavour development, texture changes, and the overall character of washed rind cheeses.

As the bacteria break down proteins, they release amino acids that deepen savoury flavour. As they metabolise fats, they create aromatic compounds that add complexity and richness.

The smell is simply the most noticeable side effect of this process.

Washed rind cheeses

Washed rind cheeses are treated very differently from bloomy or natural rinds. During ageing, the rind is repeatedly washed with brine, alcohol, or other liquids.

This regular washing keeps the surface moist and slightly salty. Moulds prefer drier environments, while bacteria thrive under these conditions.

Over time, the rind becomes dominated by bacterial communities rather than fuzzy moulds. This shift is what creates sticky, orange-tinged rinds and intense aromas.

The smell often develops well before the flavour fully matures, which is why these cheeses can seem overwhelming at first.

Why the smell is stronger than the taste

One of the great paradoxes of washed rind cheese is that it often smells far stronger than it tastes. This is because smell and flavour are experienced differently by the body.

The compounds responsible for aroma are highly volatile. They travel easily through the air and hit your nose immediately.

Flavour, on the other hand, is moderated by fat, salt, sweetness, and texture. When you actually eat the cheese, those elements balance the pungent notes into something far more rounded and gentle.

This is why a cheese can smell confronting but taste surprisingly mild.

The role of psychology in “stinky cheese”

Humans are biologically wired to associate strong smells with danger. In nature, intense odours often signal decay or spoiled food.

Fermentation, however, is not decay. It is controlled transformation.

Cheese represents one of humanity’s oldest methods of preserving milk safely. The aromas produced during ageing do not indicate spoilage when the cheese is properly made.

Instead, they reflect active microbial ecosystems doing exactly what they are meant to do.

Why some people smell feet and others smell something delicious

Smell perception is deeply subjective. It is shaped by genetics, culture, memory, and experience.

One person may interpret the aroma as socks or body odour. Another may smell meat broth, caramelised onions, or deep savoury notes.

Both reactions are valid. They are responses to the same chemical signals, filtered through different personal frameworks.

This is why washed rind cheeses tend to be so polarising. They demand engagement rather than neutrality.

Famous cheeses that often get the “feet” label

Many of the world’s best-known washed rind cheeses have reputations for strong aromas. Limburger is the classic example, frequently cited as the ultimate “foot cheese.”

Époisses is another, washed in marc brandy and famous for its powerful smell. Despite this, its flavour is often described as sweet, rich, and almost custard-like.

Taleggio, Munster, Livarot, Stinking Bishop, and Pont-l’Évêque all follow the same pattern. The rind announces itself loudly, while the paste underneath remains balanced and approachable.

Not all pungent cheeses smell like feet

It is worth making a distinction here. Not all strong-smelling cheeses produce foot-like aromas.

Different microbes create different scent profiles. Some cheeses lean towards sulphur, cabbage, mushrooms, damp cellars, or barnyard notes.

Foot-associated aromas are specifically linked to certain fatty acids and sulphur compounds produced by skin-associated bacterial pathways. That combination is what gives washed rind cheeses their distinctive reputation.

Understanding this helps demystify why some cheeses smell “human” while others do not.

Cheese rinds as living ecosystems

A cheese rind is not a single organism. It is a complex, living ecosystem.

Bacteria, yeasts, and sometimes moulds interact on the surface of the cheese. They compete, cooperate, and stabilise each other over time.

This microbial balance protects the cheese from harmful organisms while shaping flavour and texture. It is one of the reasons traditional cheesemaking is so deeply tied to place.

Local environments influence which microbes dominate, giving rise to regional differences in aroma and character.

Why strong aroma can signal quality

In traditional cheesemaking, strong aroma often reflects active fermentation rather than poor quality. It suggests that the cheese has been allowed to develop naturally rather than being heavily sanitised or simplified.

Industrial cheeses tend to be microbiologically restrained. They are designed for consistency and predictability, not complexity.

Washed rind cheeses embrace microbial life instead of suppressing it. The resulting aromas are intense, but they are also honest.

They tell you that something interesting is happening beneath the rind.

How to approach foot-smelling cheeses if you’re new to them

If these cheeses feel intimidating, the key is to change how you approach them. Let the cheese warm to room temperature before serving, which softens both texture and aroma.

Pairing matters as well. Bread, fruit, or a touch of sweetness can help balance savoury notes.

Most importantly, trust the taste more than the smell. Small bites reveal nuance that the aroma alone cannot.

Why the stink is part of the beauty

Cheese is one of the few foods that openly celebrates microbes. It does not hide them or neutralise them.

Instead, cheesemakers cultivate complex microbial communities and guide them over time. The smells that result are signs of life, activity, and transformation.

When a cheese smells like feet, it is not failing. It is expressing its biology.

That honesty is part of what makes cheese such a remarkable food.

The real takeaway

Cheeses that smell like feet do so because they share microbial chemistry with human skin. Bacteria such as Brevibacterium aurantiacum thrive in similar environments and produce similar aroma compounds.

The smell is not a warning sign. It is a by-product of fermentation doing its job.

Once you understand that, the aroma becomes information rather than offence. It tells a story about microbes, ageing, and tradition.

Final thought

The next time a cheese smells confronting, pause before dismissing it. What you are smelling is not rot or decay, but controlled microbial work.

It is protein breaking down, fats transforming, and bacteria shaping flavour in ways humans have relied on for centuries.

Sometimes, that process smells like feet.

And sometimes, that is exactly where the magic is.

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Jonah Kincaid

Cheese lover. Scientist. Created a website and a Youtube channel about cheese science because he could not find answers to his questions online. 

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The post Why Some Cheeses Smell Like Feet (& Why That’s Actually a Good Thing) appeared first on Cheese Scientist.

Butter should smell like butter. Clean. Creamy. Maybe a little nutty if it’s cultured or well-made.

So when you open the butter dish and get a whiff of something… cheesy, your brain short-circuits.

Not rancid. Not off. Just unmistakably cheese-adjacent.

This usually happens slowly. A day or two after you dragged a toast crumb through the butter. A week after someone double-dipped a knife. Suddenly the butter smells like a soft rind. Or a young Cheddar. Or the inside of a cheesemonger’s fridge.

This isn’t magic. It’s microbiology.

And it’s a perfect example of how easily butter can become a tiny, accidental cheese experiment.

Let’s unpack why breadcrumbs are the culprit, what’s actually growing in there, and why butter is far more biologically alive than most people realise.

Butter is mostly fat, but not sterile

Butter feels inert. Solid. Stable. Shelf-confident. But chemically and biologically, it’s more complicated.

Butter is an emulsion:

• Roughly 80–82% milk fat.
• Around 16–18% water.
• Plus tiny amounts of milk solids, lactose, and proteins.

That water isn’t evenly distributed. It’s trapped in microscopic droplets scattered through the fat matrix. Those droplets are small, but they’re wet, and they still contain nutrients.

From a microbial perspective, butter isn’t a desert. It’s more like a constellation of tiny oases.

On its own, butter is relatively resistant to spoilage. The high fat content limits oxygen and slows microbial growth. Salted butter is even more protective. Cold temperatures help too.

But resistant doesn’t mean invincible. All it takes is an introduction.

Breadcrumbs are microbial Trojan horses

A breadcrumb looks innocent. Dry. Toasted. Harmless.

Microbiologically, it’s anything but.

Bread is full of:

• Starches (complex carbohydrates)
• Residual sugars
• Proteins
• Yeasts and bacteria from fermentation
• Environmental microbes picked up during slicing, toasting, handling

When bread is baked, most microbes are killed, but not all. And once it cools, it becomes a fantastic landing pad for airborne bacteria and mould spores.

Now put that crumb into butter.

You’ve just added:

1. Food – carbohydrates butter doesn’t naturally have much of
2. Water-loving structure – crumbs absorb moisture from butter
3. Microbial hitchhikers – dormant but ready to wake up

That breadcrumb becomes a tiny sponge, sitting in fat, slowly hydrating itself with butter’s water droplets.

From a microbial point of view, it’s party time.

Butter + crumbs = a cheese-friendly ecosystem

Cheese microbes thrive in very specific conditions:

• Moderate moisture
• Some salt
• Limited oxygen
• Access to proteins and fats
• Time

Sound familiar?

A breadcrumb embedded in butter recreates a miniature cheese cave.

• The crumb absorbs water.
• The surrounding fat limits oxygen.
• Milk proteins and fats are right there.
• Salt levels are moderate.
• The temperature is fridge-cool, not freezer-cold.

This is especially true in butter dishes left on the counter, or pulled in and out of the fridge.

What grows first isn’t mould. It’s bacteria.

And many of those bacteria are the same types that make cheese smell like cheese.

Lactic acid bacteria don’t need much encouragement

Milk naturally contains lactic acid bacteria. Butter inherits some of them.

In cultured butter, they’re intentionally added. In sweet cream butter, they’re still present in trace amounts.

These bacteria are quiet in butter. They don’t have much lactose to work with, and the fat-heavy environment keeps them subdued.

Breadcrumbs change that.

Bread introduces fermentable carbohydrates. Suddenly, bacteria that were half-asleep have access to sugars again.

They begin metabolising.

• Not aggressively.
• Not explosively.
• Just enough to start producing metabolic by-products.

And those by-products smell familiar.

Cheese aromas come from fat and protein breakdown

That “cheesy” smell isn’t random. It comes from specific compounds.

When bacteria get to work on milk components, they produce:

• Short-chain fatty acids – buttery, tangy, sometimes sweaty aromas
• Ketones – blue cheese-like, mushroomy notes
• Sulphur compounds – savoury, oniony, cabbage-adjacent
• Amino acid breakdown products – brothy, meaty, cheesy

Butter contains plenty of fat. Breadcrumbs help unlock microbial access to it.

The result isn’t rot. It’s controlled degradation.

In other words, early-stage cheesemaking chemistry, happening accidentally in your fridge.

Why it smells like cheese, not mould

People often expect mould if something’s “gone bad”.

But mould needs oxygen. Butter is relatively oxygen-poor.

Bacteria, especially lactic acid bacteria, are much happier in low-oxygen environments. They get there first.

That’s why the smell is cheesy rather than musty.

It’s also why the butter often looks fine. No fuzz. No discolouration. Just smell.

Smell is chemistry’s early warning system.

Salted vs unsalted butter: a quiet difference

Salt matters here.

Salted butter slows microbial growth by reducing water activity. It doesn’t stop bacteria entirely, but it makes life harder.

Unsalted butter is more vulnerable.

This is why unsalted butter:

• Picks up fridge smells faster
• Develops off aromas sooner
• Shows flavour changes more readily

Add breadcrumbs to unsalted butter and you’ve removed almost every barrier.

That’s when the cheese notes bloom fastest.

Temperature swings make it worse

Butter that lives on the bench part-time is especially prone.

Every temperature change does three things:

1. Releases trapped moisture
2. Allows bacteria to wake up
3. Increases fat mobility

Warm butter lets compounds volatilise. That’s why the smell seems stronger when the butter softens.

Refrigeration slows growth again, but by then the aromatic compounds are already there.

You’re not smelling active fermentation. You’re smelling the evidence of it.

Is it safe?

This is the question everyone asks quietly.

In most cases, yes — but with caveats.

What you’re dealing with is usually low-level bacterial activity, not pathogenic growth. The smell is unpleasant but not inherently dangerous.

However:

• If mould appears, discard it
• If the smell becomes sour, rotten, or putrid, discard it
• If the butter was unsalted and left warm for long periods, discard it

Butter isn’t a high-risk food, but it’s not immune either.

Trust your nose, but understand what it’s telling you.

Cheesy ≠ instantly unsafe.
Putrid ≠ negotiable.

This is why professional kitchens hate crumbs

In professional kitchens, butter contamination is taken seriously.

Not because chefs are precious. Because crumbs change the chemistry.

A shared butter container becomes:

• Microbially unpredictable
• Aromatically unstable
• Inconsistent for cooking and baking

That’s why professional kitchens:

• Use clean knives only
• Scrape, never drag
• Portion butter aggressively

They’ve learned the hard way that butter remembers everything you put in it.

Butter is closer to cheese than we like to admit

Butter feels like a finished product. Cheese feels like a living one.

But structurally, they’re cousins.

• Both start as milk.
• Both rely on fat structure.
• Both carry microbes.
• Both evolve with time.

Cheese is just butter that leaned into microbial activity.

When breadcrumbs enter butter, you’re nudging it gently back toward its cheesemaking roots.

Not enough to become cheese. Just enough to smell like it.

How to stop it happening

If you want your butter to stay boring, clean, and reliably buttery:

• Use a clean knife every time
• Avoid dragging crumbs through the dish
• Store butter covered
• Keep unsalted butter refrigerated
• Portion butter if multiple people are using it

Butter is forgiving, but it’s not forgetful.

The quiet lesson here

This isn’t really about breadcrumbs.

It’s about how alive our food systems still are, even when we think they’re inert.

Butter isn’t sterile. Bread isn’t neutral. Your fridge isn’t paused time.

Tiny microbial decisions add up.

Sometimes they give us cheese. Sometimes they just give us the smell of it.

And once you know what’s happening, that moment of confusion at the butter dish becomes something better.

A reminder that fermentation is always waiting in the wings.

Final thought

If your butter smells faintly like cheese, congratulations. You’ve accidentally recreated the earliest steps of dairy fermentation.

Just… maybe don’t spread it on your toast.

If you enjoyed this deep dive into the weird, wonderful science hiding in everyday foods, you’ll love what I send out each week.
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Cheese is everywhere. You just have to know where to sniff.

Jonah Kincaid

Cheese lover. Scientist. Created a website and a Youtube channel about cheese science because he could not find answers to his questions online. 

cheesescientist.com

The post Why Butter Can Start to Smell Like Cheese (& the Breadcrumb You Should Blame) appeared first on Cheese Scientist.