Rosemary extract is a natural substance sourced from the leaves of the rosemary plant, used as a food additive for its antioxidants. It contains compounds like rosmarinic acid and carnosic acid that prevent food spoilage by inhibiting oxidation. To produce it, rosemary leaves are harvested, dried, and then subjected to steam distillation or solvent extraction (normally acetone or ethanol). The resulting extract is concentrated, purified, and often combined with a carrier oil. This extract is utilized in various foods as a natural alternative to other synthetic preservatives.