Optimizing extraction conditions for functional compounds from ginger (Zingiber officinale Roscoe) using response surface methodology

Extraction process was optimized for maximizing the contents of functional compounds from ginger using response surface methodology which applied Box-Behnken design. Ginger extracts were obtained at 3 levels of ethanol concentration (0-70%) of solvent, extraction time (30-90 min), and extraction temperature (50-70 degrees C) as independent variables. The 6-shogaol and 6-gingerol of the extracts were analyzed through HPLC. The significance of each term in polynomial regression equations was evaluated on functional compound contents and extraction yield in extraction process. It was verified that the regression equations were accurate with high determination coefficients over 0.892. The optimum ethanol concentration, extraction time, and extraction temperature for extraction yield were determined as 41.38%, 78.16 min, and 70 degrees C, respectively. The functional compound contents predicted at optimal conditions were as follows: 39.55 mg/g at 70%, 70 min, and 70 degrees C for 6-gingerol, 2.44 mg/g at 70%, 51.90 min, and 62.29 degrees C for 6-shogaol.