Optimization of Spray Drying Conditions of Rourea oligophlebia merr. Leaves Extract Using Response Surface Methodology

This study aimed to evaluate the influence of inlet drying temperature (140 - 170 °C), feed flow rate (30 – 40 ml/min), and maltodextrin ratio (20 – 30% w/v) on the total phenolic content (TPC) and total flavonoid content (TFC) of spray-dried Rourea oligophlebia extracts using response surface methodology (RSM). The optimized spray drying conditions were identified as an inlet temperature of 160 °C, a feed flow rate of 34 ml/min, and a maltodextrin concentration of 30% (w/v). Under these conditions, the experimental TPC and TFC values were 84.85±0.06 mg GAE/g and 33.12±0.03 mg CE/g, respectively. The spray-dried powder extract exhibited a DPPH radical scavenging activity of 92.21 ± 0.05% and ABTS radical scavenging activity of 85.16 ± 0.06%.