Effect of Gum Arabic (Acacia senegal and Acacia seyal) addition on antioxidant properties and oxidative stability of roselle juice

Abstract

Gum Arabic (GA) is the dried exudate obtained from the tree of Acacia senegal and Acacia seyal that possess a prebiotic effect on humans. Meanwhile, roselle is a popular juice that is rich in antioxidants. However, as a complex polysaccharide, the addition of GA in roselle juice may affect the antioxidant properties of the final product. Therefore, this study aimed to determine the effect of different types of GA (Acacia senegal or Acacia seyal) addition, at different concentrations (0%, 2%, 4% and 6%) on the antioxidant properties and antioxidant stability of roselle juice during storage. The most accepted formulation of juice for each GA type along with the control sample (0% GA) was analysed for their oxidative stability during five weeks of chill storage (4±1oC). Results showed that the addition of GA increased or at least maintained the vitamin C and total phenolic content (TPC) in the range of 11.35±1.26-25.18±1.70 mg/100 mL and 21.04±1.55-45.08±4.76 mg GAE/100 mL, respectively. Nevertheless, the addition of more than 2% of GA significantly reduced (p<0.05) about 7% to 25% of total anthocyanin content. Variation of results was shown by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl free radical-scavenging activity (DPPH) assay. For storage study, all juices (0% GA, 4% A. senegal and 2% A. seyal) exhibited fluctuation in trend for all the antioxidant properties except for TPC which remained stable. In conclusion, overall findings showed the addition of GA may increase or at least maintain the antioxidant properties of the juices except for anthocyanin content and antioxidant activity (DPPH assay). Meanwhile, the addition of GA had a variation that resulted in the oxidative stability of juices during storage