Color protecting processing in the pretreatment of burdock was studied to enhance polyphenols extraction. Extraction technological parameters including extraction time,ethanol concentration,extraction temperature,and solid-liquid ratio were optimized with orthogonal experiment.The results showed that VCwas the suitable color protection agent.At the concentration of 0.75%,the pretreatment of VCcould improve the extraction rate of burdock polyphenol.The result also showed that the optimal extraction condition...