In cheese manufacturing, microorganisms are important for:
the souring and ripening processes and also providing resistance against spoilage organisms
In the manufacture of cheese, microbes play an important role in the ripening, i.e., maturation of cheese and also souring, i.e., curdling of the milk to produce sour milk cheese.
1.cheese ripening is an important step which is alternatively cheese maturation of affinage. It is responsible for the distinct flavour of cheese, and through the modification of "ripening agents", ripening determines the features that define many different varieties of cheeses, such as taste, texture, and body. For example, two species of blue mold, P. roqueforti and P. glaucum give rise to the unique flavour and texture to hundreds of blue cheese which are revered throughout the world.
2. Souring is the initial step in the manufacture of sour milk cheese or acid set cheese that has been curdled (coagulated) by natural souring or by the addition of lactic acid bacteria. Lactic acid bacteria are often called "starter cultures", as they play the main role in converting the basic milk sugar, lactose, into lactic acid, a step which lowers cheese pH and makes the cheese inhospitable to many spoilage organisms.