Rosemary (Rosmarinus officinalis Linn.) extract: A source of natural antioxidants for imparting autoxidative and thermal stability to ghee

Ghee (clarified butterfat), a popular dairy product of the Indian subcontinent, develops off-flavor during storage due to autoxidation. Addition of rosemary extract (RME), a source of natural antioxidants, @ 0.1%, increased the antioxidant potential of ghee in terms of radical scavenging activity (DPPH assay) without affecting sensory and physicochemical properties. Rancimat analysis at 130 °C revealed that ghee added with RME showed a significantly higher induction period (4.4 hr) than control (1.7 hr). Based on peroxide and TBA value determinations, it was observed that shelf life of ghee added with RME was significantly higher than that of control and ghee added with BHA. Addition of RME has also imparted thermal stability to ghee and delayed the onset of cholesterol oxidation, when used as frying medium. Findings suggested that RME could be used as a source of natural antioxidants for imparting autoxidative and thermal stability to ghee. Practical applications Ghee is a major dairy product in India; about 35% of milk is converted to ghee. Though ghee is high in saturated fatty acid content (∼65%), it has lower shelf life than many vegetables oils, due to a lower level of antioxidants. BHA, a synthetic antioxidant, is permitted to be added in ghee in India. However, the current scientific evidences suggest to use natural antioxidants and avoid the synthetic ones. Our findings have shown that that addition of rosemary extract, a promising source of natural antioxidants, increased the antioxidant potential of ghee and extended its shelf life, without affecting the inherent quality of the product; it also imparted ghee with thermal stability during frying. These observations suggested that rosemary extract could be used as a source of natural antioxidants for imparting autoxidative and thermal stability to ghee.