Evaluation of physicochemical properties of anthocyanin extracts and powders from purple sweet potato (Ipomoea batatas L.)

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Purple sweet potato (Ipomoea batatas L.) is one of the food commodities that contain anthocyanin. This research aimed to evaluate the physicochemical properties of anthocyanin extracts and powders from purple sweet potato. Purple sweet potato anthocyanin was extracted using a water solvent with the addition of citric acid in different concentrations (0, 2, 4, and 6 g/100 mL). Ethanol solvent was used as a control. Foam mat drying was performed using variations of egg white composition (10 and 20 mg/100 mL). The result showed that extraction using a water solvent with 2 g/100 mL of citric acid was the most effective condition to obtain the highest total anthocyanin content (p < 0.05). However, its total phenolic, flavonoid, and antioxidant activity were lower compared to others. Total anthocyanin content of foam mat dried purple sweet potato powder made from the citric acid-water extract was significantly higher than the powder made from the citric acid-ethanol extract (p < 0.05). There was no effect in the total phenolic, flavonoid, viscosity, and yellowish-red color of the powder obtained from citric acid-water extract as the increase of egg white concentration. The use of 20 g/100 mL egg white in both powders produced from citric acid-water and ethanol extracts resulted in higher total anthocyanins and solubilities than powders using 10 g/100 mL egg white. The color of the powder obtained from citric acid-water extract had a lower brightness level and higher yellowish-red color intensity compared to the powder made from citric acidethanol extract.