Microwave-assisted Extraction of Natural Dyes from Coleus atropurpureus Leaves: The Effect of Solvent

Abstract

A microwave-assisted extraction system was used to extract natural dyes from Coleus atropurpureus leaves. The effects of water solvent of the temperature at 100°C and 80°C as well as ethanol solvent 96% were investigated. This is done at the various material to solvent ratio (0.001, 0.0025, 0.005 g/mL) and microwave power (264, 400, 600 watt). The optimal conditions of the extraction were obtained on a water solvent of the temperature at 100°C with material to solvent ratio 0.001 g/mL, irradiation power 400 watt, extraction time 10 min, material size 35-60 mesh, the optimum yield of 44.48%. Identification of groups of pigments contained in the Coleus atropurpureus leaves is known categories tannins and flavonoids. Fourier Transform Infrared Spectroscopy was used to identify the major chemical groups in the extracted dyes.