Two different concentrations of mixed Tocopherols known commercially as Covi-OxT50 (Covi 50) and Covi-OxT70 (Covi 70) together with a single concentration of a synthetic antioxidant known as Tenox 25 (T25) were added to butter and anhydrous butter fat (ABF) Ghee. Butter cookies made from the aforementioned butter were prepared and stored at tropical room temperature conditions (37-45°C and 95% RH) for 4 months. Chemical and sensory tests were performed for quality testing. The oxidative stability of ABF was performed by determining the conjugated dienes (CD), acid value (AV), free fatty acids (FFA) and peroxide value (PV) at regular intervals (2 weeks) under accelerated storage conditions (63°C for 6 weeks).
Results of the oxidative rancidity indicated that the addition of Covi 70 and T 25 to the ABF sig-nificantly (P<0.05) retarded the oxidative rancidity as measured by the aforementioned parameters. No significant effects were detected in most of the tests between Covi 70 and T25 which emphasize the outstanding effect of Covi 70 in retarding the onset of rancidity and stabilizing the ABF under the ex-perimental conditions.
Results of the chemical analysis indicated the presence of a significant (P<0.05) drop in both the moisture content and the pH values and a significant rise (P<0.05) in the TBA values of the stored cook-ies as a function of time. Both Covi 50 and Covi 70 exhibited a significant (P< 0.05) effect in maintaining the aforementioned parameters as compared to the control and the synthetic antioxidant. The sensory evaluation results showed that higher scores for the taste, odour and overall acceptance were given to the Covi 70- containing cookies as compared to the control and the other added antioxidants.