A characteristic of cheese varieties that develop blue or green streaks of harmless, flavor-producing mold throughout the interior. Known for their bold, tangy, and pungent flavors, blue cheeses are loved by those who enjoy complex, savory cheeses. The mold used in blue cheeses (Penicillium roqueforti or Penicillium glaucum) creates the distinctive blue or green veins throughout the cheese, contributing to the unique flavor that varies from creamy and mild to sharp and intensely pungent.