Determination optimization of polyphenols content in pomegranate peel extracts by Folin-Ciocalteu colorimetry

【Objective】 The study was to investigate an optimal colorimetric method to determine polyphenols in pomegranate peel systematically,and to provide an effective way to estimate the polyphenols for the value of pomegranate peel.【Method】 Using gallic acid as standard to select the density of Folin-Ciocalteu,sodium carbonate solution,reaction time and reaction temperature as impacting factors,the orthogonal design test L9(34) was used to study optimized measurement conditions,and the method was evaluated at last.【Result】 The optimum colorimetric conditions were determined as follows:the concentration of Folin-Ciocalteu reagent and Na2CO3 were 0.6 mol/L and 0.150 g/mL,reaction 50 minutes in temperature 25 ℃ away from light.There was a good linearity between the absorbance and gallic acid concentration from 1-6 mg/L(R2=0.995 8) in 765 nm.The pomegranate peel polyphenols can obtain a yield of 287.46 mg/g in this method.The average spiked recovery was 99.31%,with a RSD of 1.98%.【Conclusion】 This method,with a little reagent,fast,accurate,sensitive and stable,can be used as an appropriate method to measure the polyphenols in pomegranate peel extracts.