found a positive correlation between the formation of total polar compounds and the frying time of canola oil used to prepare French fries. These researchers used rosemary extract to prevent oxidation, and they found that this antioxidant inhibited the increased formation of total polar compounds. Also, the increased formation of polar compounds after 25 h of heating was found when cotton and sunflower oils used to fry cassava were studied. The concentration of products that
formed as a result of oxidative alteration of the oil increased as a function of temperature, limiting the usefulness of the
oil. In many countries, an upper limit of 25% total polar compounds has been established. In the present study, only the treatments without the rosemary extract (SO and TBHQ) had values above this limit
after 20 h of heating. These results reinforce the strong
activity of rosemary extract.