Effects of spice extracts on lipid fraction oxidative stability of cookies investigated by DSC

The addition of natural antioxidants to the bakery products containing fats can extend their shelf life, and it may be more attractive to consumers. In this research, the antioxidant effect of spice extracts and synthetic antioxidant on oxidative stability of fat extracted from cookies was evaluated by differential scanning calorimetry (DSC). The results revealed that addition of spice extracts to the cookies in comparison to cookies without additives reduced the oxidation as evidenced by higher the onset oxidation temperature (t _ON) of antioxidant-treated samples. Using the Ozawa–Flynn–Wall method, the activation energies (E _a/kJ mol^?1) and pre-exponential factors (Z/min^?1) and then induction times (τ/min) were calculated and also used for evaluation of antioxidants efficiency. After baking, cookies were also subjected to sensory studies and to instrumental measurements of colour changes. Among the samples studied, cookies with 0.02 % of rosemary or 0.2 % thyme extracts showed good sensorial acceptability. Cookies fortified with spice extracts also characterised greater lightness compared to the control sample.