Hello.
I'm a bit confused about which dairy products are considered fermented and which are not. Besides the obvious yogurts, buttermilk, and acidophilus milk... Skyr is fermented. Curd? Fresh cheeses? Aged cheeses?

A fermented product is one that has undergone fermentation (aging). To classify it, it is necessary to know something about the method of production, i.e., whether fermentation cultures or a natural aging process were used, or not. The use of fermentation cultures should be indicated on the product label, so this information is available; there shouldn't be a problem classifying a dairy product in this regard.

Skyr is fermented, while quark generally is not, although fermented types are also produced. Cheeses are made by coagulating milk using rennet or lactic acid; it depends on the manufacturer to decide what type of cheese they want to produce—most are subject to an aging process, i.e., the influence of used bacteria or noble molds.

Fresh cheeses (such as mozzarella, feta) and processed cheeses do not usually age (i.e., they do not ferment). On a general level, it is more complicated because, technically, during the processing of milk—its coagulation, molding, and pressing—preliminary aging occurs through so-called primary cultures (microorganisms naturally present in the food), which affect the structure and consistency of the product.

Themes:  Dairy products