Valorization of Red Sorghum bran (Sorghum bicolour) for Anthocyanin Production: Yield, Optimization and Kinetics Study

Abstract

Sorghum, an ancient cereal grain and a staple food for most families in Africa is rich in natural anthocyanin. Despite its high content of natural anthocyanin, the bran is discarded as waste and the possibility of anthocyanin extraction from it has not been given much attention. This work therefore aimed at evaluating anthocyanin extraction from red sorghum bran, and the influence of operating factors on optimizing its yield. Anthocyanin was extracted from sorghum bran using ethanol, and the extract dried and characterized for its functional groups by Fourier Transformed Infrared (FTIR) spectroscopy. Box Behnken Design of Response Surface Methodology (RSM) was employed to evaluate the effect of extraction parameters on anthocyanin concentration and yield. Bulk extraction gave anthocyanin concentration (20.05 g/L) and yield (0.09 g anthocyanin/g sorghum bran). FTIR spectra of the extract showed isothiocyanate functional groups confirming anthocyanin in the extract. Optimization gave maximum anthocyanin concentration (38.39 g/L) and yield (0.66 g anthocyanin/g sorghum bran) at the optimal condition of solvent volume;65.1 ml, temperature;75 oC and extraction time; 30.18 min. Results showed red sorghum bran as a potential source of anthocyanin and its extraction an eco-friendly means of wastes valorization.