Holes in cheese have a habit of making people suspicious. They look deliberate. They look engineered. They look like something went wrong and everyone collectively agreed not to talk about it.

And yet, when you slice into a good Havarti and see those small, irregular openings scattered through the paste, you’re not looking at a flaw. You’re looking at a record of microbial activity. A frozen moment of fermentation, captured mid-conversation between bacteria, milk, salt, and time.

Havarti doesn’t have holes because someone poked them in. It has holes because the cheese was alive while it was being made.

Let’s unpack what’s actually going on inside Havarti. And why its holes are smaller, softer, and very different from the famous eyes of Swiss-style cheeses.

First, what kind of cheese is Havarti?

Havarti is a washed-curd, semi-soft cheese, traditionally made from cow’s milk. It originated in Denmark in the 19th century and was designed to be supple, sliceable, and gently aromatic rather than firm or crumbly.

From a structural point of view, Havarti sits in an interesting middle ground.

• It’s not elastic like Mozzarella.
• It’s not dense like Cheddar.
• And it’s not engineered for big, dramatic eyes like Emmental.

That middle position matters. Because holes only appear when a cheese’s internal structure is soft enough to stretch, but firm enough to trap gas.

Havarti is exactly that.

Holes are made by gas, not by air

This is the single most important thing to understand.

Cheese holes are not pockets of trapped air. They are bubbles of gas created inside the cheese after the curd has formed.

That gas comes from bacteria.

During fermentation, certain bacteria metabolise compounds in the cheese and release carbon dioxide as a by-product. If that gas can’t escape, it accumulates. Slowly. Quietly. Pushing against the surrounding protein network.

Eventually, a void forms. That void is a hole.

In Havarti, the process is subtle. The bacteria involved are not aggressive gas producers. The curd is not designed to stretch dramatically. The result is small, irregular openings rather than big round eyes.

The washed-curd step sets the stage

To understand why Havarti gets holes at all, we need to look at how it’s made.

Havarti is a washed-curd cheese. After the curd is cut, some of the whey is drained and replaced with warm water. This step does three important things:

1. It removes lactose from the curd
2. It raises the moisture content
3. It softens the final texture

Less lactose means less fuel for acid-producing bacteria. That’s why Havarti is mild rather than tangy. But the increased moisture also creates a looser protein matrix.

That looser structure matters later.

When gas begins to form during ageing, the paste can deform slightly instead of cracking. It stretches just enough to form small cavities.

If Havarti were drier, the gas would escape or create splits. If it were wetter, the bubbles would collapse.

Holes require balance.

Which bacteria are responsible?

Havarti doesn’t rely on the classic “eye-forming” bacteria used in Swiss-type cheeses. Those cheeses use Propionibacteria, which produce large amounts of carbon dioxide and create big, round eyes.

Havarti uses a more modest microbial cast.

The primary cultures are lactic acid bacteria, which convert lactose into lactic acid early in the make. But during ageing, secondary fermentation can occur. This involves bacteria that metabolise residual compounds such as lactate and citrate.

Some of those metabolic pathways release small amounts of carbon dioxide.

Not enough for dramatic holes. Just enough for gentle openings.

This is why Havarti holes tend to be:

• Small
• Irregular
• Unevenly distributed

They’re not symmetrical. They’re not planned. They’re opportunistic.

Temperature matters more than you think

Holes don’t form instantly. They develop during ageing, and temperature plays a critical role.

If Havarti is aged too cold, bacterial activity slows. Gas production drops. The paste sets before holes can form.

If it’s aged too warm, gas production increases too quickly. The cheese can swell, crack, or develop mechanical openings instead of clean holes.

Traditional Havarti ageing temperatures allow slow fermentation. That gives gas time to accumulate gradually. The curd relaxes. The protein network stretches. Small cavities remain intact.

This slow pace is why Havarti’s holes feel integrated into the cheese, not punched through it.

Why Havarti holes are irregular

Compare Havarti to Emmental and the difference is obvious.

Swiss-style cheeses have:

• Uniform eye size
• Rounded, glossy holes
• Predictable distribution

Havarti does not.

That’s because Havarti’s gas production is inconsistent by design. The bacteria responsible are not specialised gas formers. They produce carbon dioxide as a side effect, not a primary goal.

Gas accumulates wherever the protein network is weakest. That might be near a curd junction. Or around a slightly wetter pocket. Or next to a microfracture from pressing.

Each hole tells a slightly different story.

Pressing plays a quiet role

Havarti is lightly pressed. Enough to knit the curd together, but not enough to expel all internal spaces.

That gentle pressing leaves behind micro-channels and weak points in the structure. These act as starting points for gas accumulation later.

Heavy pressing would close those spaces. No pressing would leave the cheese too fragile.

Again, Havarti sits in the middle.

Are holes a sign of quality?

In Havarti, small holes are normal. They’re expected. They’re part of the style.

That said, more holes is not always better.

Too many holes can indicate:

• Excess gas production
• Poor temperature control
• Imbalanced cultures

Too few holes can suggest:

• Over-pressing
• Over-acidification
• Ageing that’s too cold

Commercial Havarti often aims for a restrained, consistent hole pattern. Artisanal versions may show more variation. Both can be excellent.

The key is integration. The holes should feel like they belong there.

Do flavoured Havarti cheeses still get holes?

Yes. And sometimes more so.

When herbs, spices, or flavour inclusions are added, they disrupt the protein network. Each inclusion creates a local weakness where gas can collect.

This is why dill Havarti, caraway Havarti, or pepper Havarti often show more pronounced openings around the inclusions.

The cheese hasn’t changed its biology. Its structure has.

Why Havarti doesn’t get “eyes” like Swiss cheese

This is a common misconception.

All holes are not created equal.

Swiss-style eyes are the result of intentional propionic fermentation. The cheese is designed to trap large volumes of carbon dioxide. The curd is elastic. The ageing environment is warm. Everything points toward big holes.

Havarti is not built for that.

• Its bacteria produce less gas.
• Its curd is softer, not elastic.
• Its ageing temperatures are lower.

So the gas that does form has nowhere dramatic to go.

It settles. Gently.

Holes and flavour are connected

Those small holes aren’t just visual. They affect flavour.

Holes increase internal surface area. That allows oxygen to interact with the paste in tiny amounts. It also changes how volatile aroma compounds move through the cheese.

This contributes to Havarti’s mild, buttery aroma and soft dairy notes. The cheese breathes, just a little.

It’s subtle. But it matters.

What happens if Havarti has no holes?

It can still be Havarti. Especially in industrial production, where consistency is prized.

But a completely hole-free Havarti often feels denser. Less expressive. Slightly flatter in flavour.

The presence of small openings suggests that fermentation ran its course naturally. That the cheese had time to settle into itself.

Holes aren’t mandatory. But they’re telling.

A quiet record of fermentation

Havarti’s holes aren’t there to impress you.

They’re not a spectacle. They’re not a party trick. They’re a record.

Each one marks a place where bacteria exhaled. Where gas pushed gently against protein. Where the cheese yielded without breaking.

That’s what good cheesemaking looks like. Not control, but guidance.

If you enjoyed this deep dive into the quiet mechanics of cheese, you’ll love my email list. I share new articles, experiments, and behind-the-scenes cheese science straight to your inbox. No spam. Just more reasons to look twice at what’s on your plate.

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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