How Do Microorganisms Make Cheese?

Microorganisms contribute to cheese production in several ways: bacteria help acidify milk while enzymes expedite coagulation and proteins help ripen and age cheese. Cheese production follows several precise steps, employing microorganisms at each stage. These organisms give cheese structure, shape, taste and texture.

Cheesemaking essentially involves separating water from milk, which carries out over a period of time. The process begins with separating the elements in milk into two forms, which are curds and whey. Curds account for the solid particles in milk while whey exists as the liquid portion. Bacteria help separate the two components, initiating the role of microorganisms in the cheesemaking process.

Two bacteria, mesophilic bacteria and thermophilic bacteria, transform milk sugars from milk into lactic acid. They also stabilize the amount of acid in milk, reducing its acidity. Mesophilic bacteria appear in softer cheeses, such as Gouda, Mozzarella and Cheddar. These bacteria live in room temperature but die at high temperatures. Thermophilic bacteria, in contrast, survive exposure to high heat. These bacteria produce hard cheese, such as Gruyere and Romano.

After separating milk, cheesemakers add enzymes called rennet. Rennet expedites coagulation and produces stronger curds. It helps remove excess water, in turn producing thick and hard cheese. In the final ripening stage, bacteria and even fungi set to work, breaking down proteins and creating many flavors.