Abstract:  Effects of different factors, such as acid-base properties, extraction temperature, time, power and the ratio of liquidto solid on extraction of red pigment of sorghum were comparatively investigated by three kinds of methods, i.e., traditional Soxhletextraction, microwave-assisted extraction and supersonic extraction. The experimental results demonstrated that the optimalconditions for Soxhlet method were 70%(V/V)ethanol, a 3.05 of pH value, ratio of liquid to solid of 100:1(ml:g), 75℃ of extractiontemperature and extraction time of 240 min, for microwave-assisted extraction were 70%(V/V) ethanol, a 2.0 of pH value, ratioof liquid to solid of 45:1(ml:g), 720 watt of power, and extraction time of 1.5 min, and for supersonic extrction were 70%(V/V)ethanol, 65℃ of extraction temperature, 80 watt of power, ratio of liquid to solid of 45:1(ml:g), extraction time of 60 min. Theyield rate of traditional Soxhlet, microwave-assisted and supersonic extraction are 16.5%, 15.03% and 13.38% respectively.Though the yield rate of traditional Soxhlet is higher than that of microwave-assisted extraction, the microwave-assisted methodhas many advantages, such as saving time, fast extraction, low energy consumption and solvent saving for synthesis, and simpleoperation processes.

Key words: red pigment of sorghum, Soxhlet, microwave-assisted, supersonic extraction