What microorganisms are used in making cheese?

Microorganisms play a crucial role in the production of cheese by facilitating various biochemical transformations that contribute to its flavor, texture, and overall quality. Some of the commonly used microorganisms in cheesemaking include:

1. Lactic Acid Bacteria (LAB): LAB, such as Lactococcus lactis, Lactococcus cremoris, and Streptococcus thermophilus, are crucial in converting lactose, the sugar present in milk, into lactic acid through the process of fermentation. This acidification lowers the pH of milk, leading to the coagulation of milk proteins (casein) and the formation of curds.

2. Mold: Molds, primarily species of Penicillium and Aspergillus, are used to make certain types of cheeses, such as blue cheese and Camembert. By introducing mold cultures, blue veins or a white mold rind can develop on the cheese, imparting distinct flavors and textures.

3. Propionibacteria: Propionibacterium freudenreichii is primarily responsible for the characteristic "eyes" or holes in cheeses like Swiss and Emmental. These bacteria produce carbon dioxide gas during fermentation, which gets trapped within the cheese, resulting in the formation of holes.

4. Brevibacterium linens: Brevibacterium linens, also known as red smear bacteria, is used in the production of cheeses like Munster and Limburger. This bacterium is responsible for the distinctive reddish-orange rind and contributes to its unique flavor and aroma.

5. Micrococcus and Staphylococcus: Micrococcus and Staphylococcus bacteria are involved in the ripening and flavor development of certain cheeses. They act on the fat content of milk and produce free fatty acids and other flavor compounds that enhance the sensory characteristics of the cheese.

These microorganisms contribute to the fermentation, ripening, and flavor development of cheese. Cheesemakers carefully select and use specific microbial cultures to achieve the desired qualities and characteristics in their cheeses. Microbial contamination can positively or negatively contribute to the overall flavor complexity and characteristics of the final product.