Preliminary Study on Extraction and Characteristics of Mulberry Pigment

Mulberry tree has been widely cultivated for its leaves and fruits. In fruits, pigment is a kind of natural colorant and has potential commercial value. This study focuses on extraction of mulberry pigment and the stability towards sunlight, temperature, oxidant and reductant. Pigments were extracted with the solvents in the ratio of 1∶10 of sample weight to volume of extraction solvent. The results showed as follows: The optimum conditions of extraction were found to be the extraction solvent of 95% alcohol / 0 1% HCl (1∶1, ratio), a temperature of 70~oC and a extraction time of 2 h. The maximum absorption wavelength of extracts was 516 nm. The solution of mulberry pigment was unstable to sunlight, oxidant and reductant. After exposure to light for 3 weeks, the rate of colour loss of pigment reached 19 55%. When the pigment was kept at 80 ℃ for 3 h, the loss rate reached 20 90%. But it was stable at low temperature relatively. The absorbance decreased with increase of hydrogen peroxide or sodium sulfite concentrations and the colour loss of pigment increased. And the absorbance decreased correspondingly with time.