What gives Roquefort its blue veins?

Roquefort cheese gets its distinctive blue veins from the mold Penicillium roqueforti, which is introduced during the cheese-making process. This mold develops in the cheese as it ages, creating the characteristic blue-green marbling. The specific conditions of humidity and temperature in the aging caves of Roquefort-sur-Soulzon further enhance the mold's growth, contributing to the cheese's unique flavor and texture.