Why does feta cheese smell​ so bad?


Feta is a delicious cheese that has been around a thousand years ago. Like other cheese, feta comes with a remarkable acidic tang. Sometimes, people also described it as a foul or unpleasant smell, at least to the eyes of some people. Some people perceive the smell/taste as stinky feet, yeast, socks, or just like vomit.

In fact, the sour and rancid taste is a result of certain compounds produced by the bacteria living inside the cheese. As the bacteria breakdown the protein, some chemical compounds will be released in the form of gases. The particular chemical scents then got pick up by our smell receptors located in our nose, thus smell bad.

With that said, different type of cheese made in different places will have a different group of bacteria growing in it. So, the taste and smell will usually not be the same. That’s why brie, feta, cheddar, blue cheese or parmesan were all smell bad in their own way for a reason.

And for sure, cheese is not the only food out there claiming the title, there are other “smelly” fermented foods as well, e.g. the Chinese stinky tofu and Surströmming.

Which bacteria responsible for that?

After all, there are some types of bacteria responsible for the bad smell. One of which is the bacteria called Brevibacterium linens. It lives on the surface rind of the cheese and gives off an awfully rancid smell. That’s why the rind of cheese normally gave you a stronger taste.

But, why is the smell so similar to the feet? It’s because the notorious B. linen bacteria actually has cousin bacteria (same genus) called Brevibacterium epidermidis, which can be found in our sweaty skin, feet, intimate part, and armpit. And yes, that’s why your feta cheese produces a similar bad smell just like your gym socks.

Yeast & mold

Other than the bacteria, there is also yeast and mold which feast on the protein and fat content in the cheese. Thus, producing smelly compounds like propanoic acid, methanethiol, and isovaleric acid. Likewise, these are the same compounds responsible for the foot odors.

Is the white spot on parmesan the mold? check here.

The example for yeast is Geotrichum candidum.

The fresh and delicious feta cheese should look like this.

How to tell if feta has gone off?

So, you understand that feta is a fermented food and the cheesemakers purposefully left out to let bacteria to grow in them. But, little did you know that without proper handling steps it will actually go off quite fast, e.g. if you let them sit out for long. The room temperature causes various microbes to grow in them, both good and bad ones. The bad ones sometimes make harmful toxins (including histamine level raised) which can upset the stomach and make you sick.

So, it’s very much different from the intended aging room for cheesemaking, where the environment has to be cleaned and strictly controlled.

So, how do we know if the crumbled feta has gone off? The fresh crumbled feta you bought should look neat, solid with a little crumbly. The taste comes with a little natural sourness, salty, umami (a little bitter), tangy, and creamy. They shouldn’t look gluey, slimy, sticky or moldy. The feta skin has to look clean and bright, similar to tofu with a bit of texture and without any kind of black/white/yellow dots on it.

If the feta is spoiled, it usually is overly sour and has a strong unpleasant smell.

How to keep feta cheese fresh

Look at the best-by date of this brined fete by Dodoni.

Soft cheese is delicious, but aren’t known for longevity. They don’t last long, even in the fridged. Crumbled feta for example, normally has a production to expiry date anywhere from 2 weeks to 6 months, depends on how it packaged. Those that are in brine can last a bit longer if unopened. Due to the high moisture level, feta cheese can get contaminated and gone off pretty quickly compared to hard cheese.

Below I sum up a few key points for you to store your feta cheese correctly:

  • Finish them within 3-5 days (refrigerated) after opening.
  • Never leave out feta in room temperature for long, throw them away.
  • Never put the excess feta back to the brine water (package). Take feta out, close it, put back to fridge.
  • If it’s a cut feta block, you can make your own brined water for leftover/unbrined feta. Simply dissolve 2 tsp of kosher salt in 2 cups of water. Then, seal and refrigerate the container.
  • Check for signs of spoilage, e.g. mold and black dots.

If there is visible mold already, it’s highly possible that the whole package has been contaminated. Scrapping them off will not work in soft cheese, you should just discard them instead.

Continue reading: The FODMAP in gorgonzola cheese? answered.

AaronMH

I have a background in biotechnology, and I love cats.

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