Abstract:
The effects of antioxidants on the oxidative stability of butter, under different storage time and temperature conditions, were evaluated. Natural (alpha-tocopherol) and synthetic (BHA and BHT) antioxidants were added to the butter samples at two concentrations (50 and 100 ppm) immediately after the butter samples were produced from the pasteurised sweet cream, after which they were kept in the dark at 4 and -20 degrees C for 6 months. Peroxide value (PV) and thiobarbituric acid (TBA) number and the residual antioxidants of the samples were examined at 30-day intervals, starting on the second day until the end of the storage period. The measurements obtained by assaying PV and TBA number in butter samples showed that both the synthetic and natural antioxidants used were capable of protecting the butter samples against oxidation during storage at both temperatures. The butter samples with 50 ppm antioxidant could be stored for more than 180 days at 4 degrees C without spoilage. At -20 degrees C, the addition of BHA, BHT and alpha-tocopherol caused a reduction in the TBA number from 0.31 (control) to 0.21, 0.23 and 0.27 mg malonaldehyde/kg butter, respectively, and the PV decreased from 0.75 (control) to 0.46, 0.56 and 0.54 meq O(2)/kg butter, respectively, after 6 months of storage. The highest residue values were determined in both the 100 and 50 ppm a-tocopherol-containing samples. These results indicate that alpha-tocopherol exhibited a very strong antioxidant activity, which was almost equal to that of the synthetic antioxidants. Therefore, the use of a-tocopherol is recommended as a natural antioxidant to suppress the development of rancidity in butter.
