Abstract: Objective: To optimize the extraction process of chlorogenic acid in sweet potato leaves. Methods: With the content of the extract and extraction rate of chlorogenic acid as indexes by orthogonal design, several extraction processes were compared respectively, such as traditional decocting method, the ethanol refluxing method, the ultrasonic method etc. The factors affecting the extraction rate such as the concentration of extracting solvent, the extracting time, the ratio of solid and liquid were investigated. The content of chlorogenic acid was determine by ultraviolet-spectrophotometry. Results: The optimum extrac- tion is refluxing method. The optimum extraction conditions were: 75% ethanol, solid and liquid ratio 1:20 and refluxing 1.5 h. Under these conditions the content and chlorogenic acid and extraction rate reached the highest levels. The factors influencing this extraction efficiency were as follows: Consistency of ethanol>times of reflux>ratio of solid and liquid.

Key words: sweet potato leaves, chlorogenic acid, ethanol refluxing method, extraction process