An approach towards optimization of the extraction of polyphenolic antioxidants from ginger (Zingiber officinale)

The present study aims to maximize the extraction of polyphenols from ginger (Zingiber officinale) through the statistical optimization of three influential process parameters ethanol (EtOH) proportion (%), temperature (°C) and extraction time (min). Response Surface Methodology (RSM) was employed to design experiments and study the interaction effects of these parameters on the extraction process. Analysis of Variance (ANOVA) was used for the analysis of regression coefficient, prediction of equation and case statistics. The optimum conditions for the maximum yield of polyphenols from each gram of ginger were found to be 75 % aqueous EtOH, 40 °C temperature and extraction time of 60 min respectively. The order of relative importance of these three parameters was: EtOH > time > temperature. Antioxidant activity of the extracted polyphenols using optimized parameters was also determined by DPPH assay. DPPH radical scavenging activity of ginger extract was compared with Vitamin C and butyl hydroxy toluene (BHT). Finally, this study revealed a cost effective analytical model to maximize the extraction of polyphenols from ginger with higher antioxidant activity. It was also concluded that at lower concentration ethanolic extract of ginger possess high antioxidant activity in comparison with synthetic antioxidants like vitamin C or BHT and thus it can be applicable as potent natural antioxidant in food and pharmaceutical industries for the preparation of functional food.