Extraction of Anthocyanin Rich Natural Colour from Dried Kokum Rind Using Microwave-Assisted Extraction

Abstract

Growing interest in naturally derived food colourants has encouraged the development of efficient methods for recovering anthocyanins from plant materials. This study investigated microwave-assisted extraction of anthocyanin-rich colour from dried kokum (Garcinia indica Choisy) rind and evaluated the effects of ethanol concentration and extraction time on selected physicochemical properties. Response surface methodology was applied using 13 experimental runs, with ethanol concentration and extraction time as independent variables and microwave power maintained at 1350 W. The concentrated extracts were evaluated for pH, total soluble solids, total anthocyanin content, redness (a*), and titratable acidity. Across the experimental treatments, total anthocyanin content ranged from 273.3 to 348.1 mg/100 g, while a* values ranged from 28.90 to 36.80. Numerical optimisation predicted optimum conditions of 71.79% ethanol and 3.72 min extraction time. Experimental validation under these conditions produced a pH of 1.94, total soluble solids of 14.39 °Brix, total anthocyanin content of 343.60 mg/100 g, a* value of 34.74, and titratable acidity of 4.31%. The differences between predicted and experimental responses were limited, with reported coefficients of variation ranging from 0.76 to 6.28%. These findings indicate that controlled microwave-assisted extraction can provide rapid recovery of anthocyanin-rich colour from dried kokum rind under the investigated conditions.