Bacteria in Parmesan: Is It Fermented?

Last Updated on September 25, 2023 by Aaron

Parmesan cheese, officially known as Parmigiano-Reggiano when it originates from the designated areas in Italy, is a hard, aged cheese that is renowned for its rich flavor and granular texture.

The production of Parmesan involves the use of bacteria, which are responsible for the fermentation and the development of the cheese’s distinctive taste and texture.

Probiotic Bacteria in Cheese Fermentation

Like many cheeses, Parmesan production begins by adding starter cultures to milk. These cultures typically contain lactic acid bacteria, such as Lactobacillus and Streptococcus species. You can see the detailed steps in this article. These bacteria convert the lactose (sugar) in milk into lactic acid, which initiates the fermentation process. This drop in pH coagulates the milk proteins, forming curds.

Producers can use different combinations of bacteria, or starter cultures, when making cheese, and this is one of the reasons why there are so many different varieties and flavors of cheese available. The choice and combination of bacteria will influence the flavor, texture, aroma, and other properties of the cheese.

For Parmesan and other traditional PDO cheeses, there are often specific strains of bacteria that are typically used, and these have been selected over time for the qualities they impart to the cheese. However, even within the category of a specific cheese like Parmigiano-Reggiano, there can be subtle variations in flavor based on the specific bacteria used, the feed given to the cows, the time of year the milk was produced, and other factors.

Most of the time, two primary types of bacterial cultures are mesophilic cultures: These bacteria thrive at moderate temperatures and are used for cheeses like Cheddar, Colby, and Gouda. Common mesophilic bacteria include Lactococcus lactis and Lactococcus cremoris.

And, thermophilic cultures: These bacteria are adapted to higher temperatures and are used for cheeses like Parmesan, Mozzarella, and Swiss. Common thermophilic bacteria include Streptococcus thermophilus and Lactobacillus helveticus.

The primary bacteria used in Parmigiano-Reggiano1 production are the Lactobacillus strains, including the Lactobacillus helveticus, Lactobacillus lactis, and Lactobacillus bulgaricus. The Streptococcus thermophilus is often being used in tandem as well, it’s known for producing lactic acid quickly, helping in the curdling process.

A study analyzed 187 bacteria strains from the different stages over 24 months in Parmigiano Reggiano cheese production. The bacteria species clusters showed a high biodiversity and complexity presence in the cheese.

In addition to the added starter cultures, the raw milk used for Parmigiano-Reggiano PDO contains its own natural microbial flora. These native microorganisms, which can include various strains of lactic acid bacteria, further contribute to the fermentation process and the cheese’s unique flavor profile. That’s why it’s hard to find the same taste outside of the restricted PDO region.

As the cheese ages, different strains of lactic acid bacteria become more prominent, contributing to the ripening process and flavor development. These can include strains like Lactobacillus casei (which contributes to the flavor and browning of parmesan2) and Lactobacillus rhamnosus3, which is also a probiotic.

As on the surface or rind of Parmesan,

can also host beneficial bacteria and molds that contribute to the maturation and flavor profile of the cheese. Some examples are actinobacteria (such as Corynebacterium), micrococci, molds (like the Penicillium species), and even colonies of yeast especially in the earlier stages of aging4,5,6.

The presence of beneficial microorganisms is a characteristic of many aged cheeses, not just Parmesan. These microorganisms can have numerous effects, from enhancing flavor to protecting the cheese from harmful pathogens. In fact, some of the flavors and aromas of aged cheeses are due to the metabolic by-products of these bacteria and molds.

But, how about the white spots on parmesan, is that mold? we’ve discussed previously.

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