Extraction Technology of Chlorogenic Acid in Sweet Potato Leaves and Stems

Chlorogenic acid from sweet potato leaves and stems were extracted by immersion-reflux method,ultrasonic method and immersion-ultrasonic extraction method,respectively.By comparison of these methods,an optimum process was obtained.The factors affecting the extraction rate,such as the extraction number of times,the time,temperature and power of ultrasonic extraction,as well as the ethanol concentration,were investigated.The results showed that the immersion-ultrasonic extraction method is suitable to get higher yield of Chlorogenic acid.The optimum extraction conditions were shown as follows: immersing the leaves and stems in 70% ethanol for 12 h,then extracting two times with 80 W ultrasonic power at 70 ℃ for 20 min each time.Ultraviolet-spectrophotometry test showed that the content of chlorogenic acid reached the highest levels under these conditions.