Why Parmesan Cheese Smells Like Vomit…? Fruity…? Plastic…?

Parmesan cheese is known for its intense, powerful aroma which can be likened to vomit for some. It’s also known as “rancid”, “piquant”, or “baby’s breath”. While the smell may be unpleasant to some, it doesn’t mean that the cheese is bad or spoiled. It is normal and the cheese is safe to eat.

This smell comes from a compound called butyric acid that is produced when the cheesemaking process breaks down proteins and fats in the milk. In addition to being found in parmesan, the “stinky fat” butyric acid is also naturally occurring in dairy products like butter and yogurt, and in some other fermented foods like pickled cucumber and fermented soy products.

Due to the long ripening, hard cheeses like parmesan cheese contain a high level of butyric acid. A study (1) showed that Parmigiano Reggiano cheese aged for 12 months contains 59 milligrams of butyric acid per 100 grams of fat, while 24 months Parmigiano Reggiano contain 144 milligrams of butyric acid per 100 grams of fat.

Furthermore, the outer part of a cheese wheel contains more butyric acid compared to the inner part of the wheel. So the smell tends to be stronger closer to the cheese rind. Below is the result for 1 month, 6 months, 12 months, 18 months, and 24 months, respectively:

  • The butyric acid of the inner wheel: 3.4 mg, 17.5 mg, 29.9 mg, 38.8 mg, and 71 mg.
  • The butyric acid of the outer wheel: 3.8 mg, 25.2 mg, 50.4 mg, 83.3 mg, and 123.9 mg.

Several other volatile compounds contributing to the pungent smell of parmesan cheese are ammonia, sulfur compounds, and volatile fatty acids. These compounds are produced as a result of microbial activity, which is essential for the ripening process of parmesan cheese.

Fruity Smell

Parmesan cheese can also have a sweet and fruity smell. This is commonly caused by volatile compounds such as aldehydes, alcohols, and esters. It’s described as a pineapple, lemony, or berry-like aroma and is usually desirable in aged parmesan cheese.

To name a few, ethyl butyrate contributes to a pineapple-like smell, benzaldehyde gives floral or almond-like smell but also slightly bitter, and isopentanol provides a citrusy or sweet odor. Furaneol, also known as strawberry furanone, gives a sweet and fruity smell reminiscent of strawberries.

Does parmesan cheese smell like plastic?

It is possible for parmesan cheese to smell like plastic due to a compound called dimethyl disulfide. It has a strong odor, likened to that of garlic-like or propane. This sulfur-containing compound could be produced by some bacteria, such as Bacillus subtilis and Brevibacterium linens, which are present in parmesan cheese.

However, good parmesan doesn’t normally smell anything like plastic. The cheese might also be stored for too long in the fridge, contaminated or spoiled — which can lead to the plastic-like smell. If you encounter any out of the ordinary smell from your parmesan cheese, it is best to discard it and purchase a new one. Read our previous post about the signs when parmesan gone bad.

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