The measure of acidity is a test commonly used to evaluate the oil quality especially during frying. The acidity evolutions of the formulated oils during heating experiments. This parameter was still stable in both oils until 6 h of heating. The oil
formulated with a reaction kept stability in its content of free fatty acids until 12 h. The acidity increase significantly (p < 0.05) and reach 0.1% and 0.075% in control and rosemary treated oils respectively after 18 h of heating. This difference between the values of acidity is indicative of polyphenols ability to retard oils oxidation causing the fatty acids releasing. reported the