Blue cheese of blue veins. The distinctive flavor and aroma of blue cheese arises from methyl ketones (including 2-pentanone, 2-heptanone, and 2-nonanone) which are a metabolic product of "Penicillium roqueforti". These compounds are not formed in other types of cheese fermented by bacterial acidification alone. In the European Union, many blue cheeses, such as Cabrales, Danablu, Gorgonzola, Roquefort and Blue Stilton, carry a protected designation of origin, meaning they can bear the name only if they have been made in a particular region. Similarly, individual countries have protections of their own such as France's Appellation d'Origine Contrôlée and Italy's Denominazione di Origine
Sour milk cheese with caraway (e.g. traditional Latvian Jāņi cheese). In Germany the term "Sauermilchkäse" is usually applied to ripened acid-set cheeses only, but not to fresh cheeses. The various types of ripened sour milk cheese include: Sour milk cheese Sour milk cheese or acid-set cheese is a cheese that has been curdled (coagulated) by natural souring or by the addition of lactic acid bacteria, such as traditional curd cheese or cottage cheese. Sour milk cheese does not use rennet for coagulation. Sour milk cheese generally ripens for no more than two weeks in comparative warmth. 100 litres of milk yield about 8