Antioxidant activities of rosemary and sage extracts in rapeseed and sunflower oils
1999
Nguyen, H.T.T. | Pokorny, J. (Vysoka Skola Chemicko-Technologicka, Prague (Czech Republic). Ustav Chemie a Analyzy Potravin) | Korczak, J.
The antioxidant activity of rosemary and sage extracts was tested in zero-erucic rapeseed oil and high-linoleic sunflower oil under conditions of the Schaal oven test at 40 deg C. Acetone, ethyl acetate and hexane extracts were found more active than ethanol extracts in both oils. Rosemary extracts were found more active than sage extracts. Rapeseed oil was stabilized more efficiently than sunflower oil. The antioxidant activities rose linearly with the concentration of antioxidants in the range of 0.01-0.10 % in rapeseed oil, but the relationship was logarithmical in sunflower oil. Antioxidants inhibited autooxidation reactions during the induction period, proportionally to their concentration. The protection factors showed that the oxidative stability could not be increased more than twice, applying conventional concentrations of 0.01 to 0.02 %, but could be increased substantially by increasing the content of extracts to 0.05-0.10 %.
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