An optimal extraction solvent and purification adsorbent to produce anthocyanins from black rice (Oryza sativa cv. Heugjinjubyeo)

Abstract

Black rice was used to produce anthocyanins, an important natural red food colorant. Integrated methods for extraction and purification of anthocyanins were investigated. Four solvents and 6 adsorbents were used for extraction and purification, respectively. Acidified 70%(v/v) ethanol resulted in the highest anthocyanin extract concentration of 461.72 mg/L. Amberlite XAD7HP had the highest adsorption capacity of 0.406 +/- 0.010 mg/g of adsorbent and desorption capacity of 0.252 +/- 0.016 mg/g of adsorbent. Acidified ethanol effectively eluted anthocyanin pigments from Amberlite XAD7HP at a concentration of 60%(v/v). Experimental adsorption data best fit to pseudosecond-order kinetic and Langmuir isotherm models. Purification parameters were optimized through dynamic adsorption/desorption experiments with Amberlite XAD7HP. The concentration of sugars (impurities) decreased from an initial 452.78 mu g/mL to 169.75 mu g/mL after purification.