摘要：The purpose of this work is the comparative study between the antioxidant activity of the methanolic extracts of Rosemary (Rosmarinus officinalis L.) and beta-carotene. Rosemary extracts provide a major source of natural antioxidants used commercially in foods. Beta-carotene is also a powerful antioxidant, and has been shown to help guard against cancer and heart disease. Rosemary extract was prepared under refluxing condition, and beta-carotene was prepared by extraction of carrots. These extracts were used as antioxidants at a concentration of 0,02%, to improve the stability against oxidation in following samples: sunflower oil (S1), extravirgin sunflower oil (S2), lard (S3) and soybean oil(S4). We used the volumetric method (tiosulphatometria) for determination the peroxide value not only at soft thermic treatment (60 °C) but also at some advanced (microwave) for various periods of time. The peroxide value of the samples was determined when the samples were without antioxidant (control), and after being aged at 600C in the dark for 7, 11, 14 days, respectively. The decrease in the rate of formation of peroxides was used as a measurement of the antioxidant activity of the extracts. Increasing temperature, the efficiency of antioxidants decrease in all the samples. Addition of antioxidants slowed down the formation of peroxides in the samples stored in clear glass bottles at roo m tem perature under diffused daylight. Beta-carotene is more active than Rosemary extract in some concentration and some samples; it is though that both of extracts as natural sources of antioxidants. Totally, antioxidant efficiency decreased with increasing temperature.
