Abstract: In order to promote the comprehensive utilization of Polygonatum kingianum residue , the insol-uble dietary fiber (IDF) from Polygonatum kingianum residue in Yunnan Province was extracted by am.ylase and protease. The effects of the amount of enzyme , pH and temperature on the extraction rate of dietary fiber were studied by single factor experiment. The Box-Behnken response surface analysis was usedto optimize the extraction conditions of dietary fier from Polygonatum kingianum residue. The resultsshowed: the a-amylase addition amount was 176 U/g, the enzymatic hydrolysis pH was 6, the enzymatichydrolysis temperature was 56 C ; the alkaline protease addition amount was 6 100 U/mg, the enzymatichydrolysis pH was 9, the enzymatic hydrolysis temperature was 55 C . Under this condition , the averageextraction yield of IDF was 62. 86% , the water holding capacity of IDF was 9. 76 g/g, the oil holding capacity was 5.74 g/g, and the expansion capacity was 5. 86 ml/g. The extraction process was stable andreliable, which provided a reference forimproving the value of Polygonatum kingianum by product and de.veloping of health food.

Key words: Polygonatum kingianum residue, insoluble dietary fiber, response surface methodology :double enzyme, process optimization