Optimization of maltodextrin concentration, drying temperature and drying time on total flavonoid content and antioxidant activity of black garlic (Allium sativum L.) aqueous extract powder using response surface methodology

The purpose of this research was to optimize the drying process and maltodextrin concentration of black garlic (Allium sativum L.) aqueous extract powder using the response surface methodology. The process conditions were based on the Box-Behnken design, with 17 kinds of variations in the drying temperature (50-70 °C), drying time (18-30 hours), and maltodextrin concentration (5-15 %). The moisture content, total flavonoid content and antioxidant activity (DPPH, ABTS, FRAP) of black garlic extract powder were significantly higher at temperature of 60 °C, drying time of 30 hours and maltodextrin concentration of 5%. In this condition, total flavonoid content (14.372 mg QE/g), DPPH radical scavenging (19.616 mg TE/g), FRAP radical scavenging activity (27.661 mg TE/g) were excellent. Overall, the drying process conditions for the optimized biological activities of black garlic extract powder were expected to be at 59.95 °C, for 30 hours with 5% maltodextrin concentration.