Effect of boiling on bioactive compounds and radical scavenging activity of anthocyanin-rich vegetables: Red amaranth and red skin potato

This study was conducted to determine the optimum boiling time resulting in maximum retention of the bioactive compounds and radical scavenging activity. For this analysis, two most commonly consumed anthocyanin-rich vegetables , red amaranth (Amaranthus tricolor) and red skin potato (Solanum tuberosum) were exposed to boiling for 0, 1, 5, 10, and 20 minutes. Then the effects of boiling times on physicochemical, bioactive compounds, and antioxidant activity by DPPH radical scavenging ability were analyzed. In physicochemical analysis, ash content was decreased significantly, and the pH value increased significantly as the boiling time increased (p<0.05). The % of WSI was increased significantly as the boiling time for red amaranth as well as red skin potato (p<0.05) increased. The total polyphenol content (TPC), total anthocyanin content (TAC), total carotenoid content (TCC), and radical scavenging activity (RSA) of red amaranth and red skin potatoes were gradually reduced with the increasing of boiling time. The first - order kinetic model showed the good fit for the loss of total phenolic, carotenoids, anthocyanin, and DPPH radical scavenging activity of red amaranth and red skin potatoes with 0.86 - 0.98 coefficient of determination (R2). The findings could encourage both the household boiling and the food industry to recommend specific boiling time to maintain vegetables' antioxidant properties.