Roasting Conditions for Optimization of Citri Unshii Pericarpium Antioxidant Activity Using Response Surface Methodology

Abstract

This study was conducted to establish roasting conditions for optimization of Citri Unshii Pericarpium antioxidant activity using response surface methodology (RSM). A central composite design was applied to investigate the effects of two independent variables, namely roasting temperature (40∼100°C; X1) and roasting time (5∼15 min; X2), on responses such as electron donating ability (Y1), total phenolic content (Y2), total flavonoid content (Y3), and hydroxyl radical scavenging activity (Y4). The maximum electron donating ability was 72.38% at a roasting temperature of 71.12°C and roasting time of 9.39 min. The maximum total phenolic content was 10.76 mg tannic acid equivalents/g at a roasting temperature of 69.71°C and roasting time of 8.39 min. The maximum total flavonoid content was 105.99 mg quercetin equivalents/100 g at 72.54°C and 8.64 min. The maximum hydroxyl radical scavenging activity was 60.33% at 68.97°C and 9.84 min. Based on the superimposition of three dimensional RSM with respect to electron donating ability, total phenolic content, total flavonoid content, and hydroxyl radical scavenging activity under various conditions, optimum conditions were established as follows: roasting temperature of 70.90°C and roasting time of 9.03 min.Key words: Citri Unshii Pericarpium, roasting conditions, antioxidant activity, response surface methodology, optimization