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
Sheep milk cheese especially when produced outside their country of origin. It takes between 2 weeks to 2–3 months up to two years for the cheeses to fully ripen. French sheep milk cheeses include Abbaye de Bellocq, , Berger de Rocastin, Brebicet, Le Claousou, Lévejac, Valdeblore, Roquefort, Ardi-gasna, Agour, Ossau-Iraty, Brocciu, Asco, Brin d'amour,Faisselle, Fleur de Maquis, A filetta, and Niolo. Greek sheep milk cheeses include Feta and Halloumi. Italian sheep milk cheeses include Pecorino Romano, Pecorino Sardo, Pecorino Siciliano, Pecorino Toscano and Ricotta. Israeli Sheep milk cheeses Tzfatit tari(fresh Tzfat cheese)and Tzfat cheese |Tzfatit Kasheh]] Aged Tzfat cheese Croatian sheep milk cheeses