Day 530 – Swiss cheese has holes because of Proprionibacterium, obviously.

Other 6000 miles… Cheese posts

2011: Andile Lungisa threatens us all
2017: Incoming from Jesse Miller (features a terrible Cheese rap)
2019: Posh cheese at a ridiculous price

But. On with today’s cheesy offering.

Long story short, Mrs 6000 bought some Swiss cheese from a cheese shop near Hermanus and it was full of holes. The kids wanted to know why.

Obviously, this was an Emmentaller cheese – the traditional one with the holes. Emmentaller isn’t like Champagne (which, if you think about it, is also full of (very small) holes), in that to be Emmetaller cheese, it doesn’t actually have to be made in Emmental. So although it’s not Swiss, it’s still street-legal holey cheese.
But why? Well, it’s thanks to a Proprionibacterium – this one:

Propionibacterium freudenrichii subspecies shermanii

Easy for you to say.

Like many other cheeses, Swiss cheese is made with cow’s milk and contains bacteria that help convert the milk into a solid.

So why does Swiss cheese have holes? Also called “eyes,” they’re so essential to Swiss cheese that when they’re missing, the cheesemakers say the batch is “blind.”

Under the specific conditions that Swiss cheese is made, the P. shermanii produce a gas: carbon dioxide.

Because Swiss cheese is made at a warm temperature – around 70 degrees Fahrenheit – the cheese is soft and malleable. So as the bacteria grow, the gases they emit end up creating round openings. 

But when a bubble has formed inside a hunk of warm cheese – and then that cheese is cooled to around 40°F – the hole stays in place. The cheese now has its eyes.

Unless you’re in the cheese industry, or you’ve only heard of Proprionibacterium from what you’ve read above, then Proprionibacterium is best known for causing acne.

But don’t let that put you off your cheese.


P.S. Yes, beagle-eyed reader, you’re right. I had to do a quick renumbering of posts from the last couple of weeks after I saw that today was day 530 of lockdown on a TV screen in a Radiology Department Waiting Room (more on that another time). I’d done two 513s.
This sort of thing happens. It’s rectified. It’s all ok.