Evaluation of the Antioxidant Activity of Citrus Flavedo Extracts in Food Systems

Abstract

The worldwide trend to avoid the use of synthetic antioxidants has motivated scientists to unveil and exploit new sources of natural antioxidants. In this study, the antioxidant potential of the flavedo extracts of two locally grown citrus fruits namely, Mandarin fizu and Pamplemousse kaopan, was investigated in mayonnaise prepared from unstripped soybean oil and in bulk unstripped soybean oil. The antioxidant activity of the mandarin extract at two concentrations (0.2% (m/m) and 0.4% (m/m)) was compared to 0.02% (m/m) BHT. Hydroperoxide formation was monitored during storage at 45^oC by measuring peroxide value (PV) and conjugated diene value (CD). PV values showed that the mandarin extract was as effective as BHT (p>0.05) and more effective than Pamplemousse kaopan extract (p<0.05) in retarding lipid oxidation in mayonnaise during storage. After 12 days of storage, the CD values of the mayonnaise samples increased in the following order: mandarin extract < BHT < control < pamplemousse extract. Increasing the concentration of the flavedo extract of Mandarin fizu to 0.4% did not increase the effectiveness of the extract in controlling lipid autoxidation in mayonnaise (p>0.05). In unstripped soybean oil, mandarin extract at 0.4% (m/m) was found to be less effective than BHT but more effective than the extract at 0.2% (m/m) (p<0.05). A similar picture was noted for the conjugated diene data. The findings of this research point to the value of Mandarin fizu flavedo extracts as potential sources of natural food additives.

Keywords: Flavedo, Mandarin, Pamplemousse, Mayonnaise, Soybean Oil, Peroxide Value, Conjugated Diene Value, Antioxidants