Effects of Extraction Conditions on Total Phenolic Content and Total Flavonoid Content of Roselle (Hibiscus sabdariffa L.) Extracts
The objective of this study was to determine the optimal value of factors affecting the extraction of compounds such as, polyphenols, flavonoids of Roselle. The investigated factors included extraction temperatures (30, 40, 50, 60, 70 and 80°C), extraction time (30, 60, 90, 120 and 150 minutes) and solid to solvent ratio (1:5, 1:10, 1:20, 1:40 and 1:50 g/mL). The efficiency of extraction was evaluated based on total phenolic content (TPC) and total flavonoid content (TFC). The results showed that temperature range of 60–80°C was the appropriate temperature for TFC while extraction temperature over 60°C was suitable for achieving highest TPC. Considering the effect of extraction time, duration of 90–150 minutes facilitated the extraction of both phenolics and flavonoids. Moreover, the solid to solvent 1:20 was chosen for extraction process based on the balance of antioxidant contents and their yield.