The Bacteria in Parmigiano Reggiano


Cheese is a product of fermented milk. For fermentation to occur, we have to welcome a huge diversity of bacteria population to come in to help, sometimes, unavoidably the bad one as well.

In microscopic level, many good bacteria work together to process (metabolize) substances in the curd mass, raw/processed milk, and aging cheese at different stages to give out a desirable taste, aroma, and texture for the cheese. In fact, the longer fermentation (aging) process which takes up years to complete is what decides the cheese quality.

During the cheesemaking process, you will usually see the salt being mixed or brined with the cheese. That is an essential step to get rid of the unwelcoming harmful bacteria at bay, but having the good one inside overgrown. Plus, it adds a bit of saltiness flavor to the mild taste.

Oh don’t forget, there is the same “umami” taste in feta as well.

Parmigiano Reggiano

One good example would be the Parmigiano Reggiano. Parmigiano Reggiano has been known to be one of the best cheese that can only be made in a specific region in Italy. And that’s because of the presence of the certain type of bacteria in that region, which got eaten by cows and made their way into the milk and later the cheese production.

These bacteria are present naturally in the milk, grass and whey starter (the remains of the previous day).

This image showed the bacteria grew on one of the agar media. The white dots being the colonies of bacteria.

How many type of bacteria?

Studies (1, 2) have found over 180 strains of bacteria present throughout the Parmigiano Reggiano’s cheesemaking process. These normal-to-high temperature ranges of (thermophilic and mesophilic bacteria) bacteria have their population changes in different processing stages.

Overall, the lactic acid bacteria has a dominant population. They resist the growth of other microbes.

Respectively, they were found in different numbers throughout the 6hr/12hr/48hr of curd stage, in the raw milk and whey starter, cheese stage, and brined cheese stage. Below are the different species of bacteria involved in the process:

  1. Lactobacillus delbrueckii 
  2. Lactobacillus helveticus
  3. Lactobacillus casei
  4. Lactobacillus brevis
  5. Lactobacillus paracasei 
  6. Lactobacillus rhamnosus
  7. Lactobacillus plantarum 
  8. Lactobacillus fermentum
  9. Lactobacillus parabuchneri
  10. Pediococcus acidilactici
  11. Kocuria kristinae
  12. Lactococcus lactis
  13. Enterococcus faecium
  14. Enterococcus faecalis
  15. Streptococcus thermophilus

When and where they showed up?

To be exact, the thermophilic lactic acid bacteria (~113°F) such as the Lactobacillus helveticus and Lactobacillus delbrueckii were both found predominantly in the ingredients (milk, starter, whey, and curd) and in the first 2 weeks of aging (3).

The number of them slowly reduces from there onward, and the mesophilic bacteria (~72°F) started to kick in and increased in numbers, which includes Lactobacillus casei, Lactobacillus rhamnosus, and Pediococcus acidilactici.

There are other bacteria maintained mostly constant throughout the cheesemaking process, Lactobacillus paracasei for example.

So, with the bacteria, why can’t we make the exact cheese elsewhere?

Without all these, the appreciated cheese can’t be called Parmigiano Reggiano. Even if we have these bacteria cultured in the lab, we still can’t replicate Parmigiano Reggiano elsewhere in the world. Why? It’s simply because of these bacteria is not all, but part of a myriad microorganism that takes part in the unique ecosystem in Reggio Emilia.

Most of the current study focuses on a number of specific species of bacteria. The rest remained largely to be understood.

Other Parmigiano Reggiano in the market, also called the “fake” Parmesan cheese, that made in different places outside of the DOP region will have similar bacteria in it, but will not be the exact same. And thus the taste.

What about the mold in blue cheese? read here, yuk.

AaronMH

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

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