Four factors were examined in this study, including the ethanol concentration (30, 50, 70, and 100%), the extraction temperature (40, 50, 60, and 70 °C), the extraction time (30, 45, 60, and 90 minutes) and the solid to solvent ratio (1: 5, 1: 10, 1: 15, and 1: 20 g / mL).