Microwave-assisted Extraction and Stabilization of Yellow Pigment from Corn Bran

Yellow pigment is traditionally extracted from corn bran with organic solvent in water bath. This extraction method, however, is reagent- and time-consuming, greatly toxicity-causing and lowly effective, and the yellow pigment extracted by the method is easily oxidized. This study aimed to set up a microwave-assisted organic solvent extraction method of yellow pigment from corn bran. The one-factor-at-a-time method was applied to investigate four parameters affecting the extraction of yellow pigment, and then the four parameters were optimized using orthogonal test design. Furthermore, stability of the yellow pigment under various environmental conditions was analyzed. The results showed that the optimal microwave-assisted extraction conditions were as follows: microwave power 400 W, ethanol concentration (extraction solvent) 80%, irradiation duration 60 s, and material/liquid ratio 1:8. Common food additives such as sugar, citrate acid and chloride sodium had little effects on stability of the yellow pigment, while sodium benzoate had some effect. The yellow pigment had good heat resistance, but poor light resistance. Good oxidation resistance was observed in it, but its reducing resistance was slightly poor. The yellow pigment was stable in acid, neutral and weakly alkaline media.