Abstract: The determination method of plant soluble sugar by HPLC-ELSD has the advantages of high sensitivity, low detection limit and large linear range. In order to understand the soluble sugar components and saccharification characteristics of sweetpotato varieties, the soluble sugar content of 11 important sweetpotato germplasm resources had been measured and analyzed. The results showed that fructose, glucose, sucrose and maltose were all contained in the soluble sugars of both raw root and cooked root,and the average content of the tested group were 58.41 mg·g^-1 and 123.05 mg·g^-1, respectively. Among the soluble sugars in raw root, sucrose content was the highest, accounting for about 45% of the soluble sugars, while maltose was the least, only accounting for about 10% of the soluble sugars. Among the soluble sugars in cooked root, maltose was the highest, about 90% of which came from the conversion of starch during steaming, and the increment accounted for more than 50% of the soluble sugars in cooked root. Fructose, glucose and sucrose in cooked root mainly came from soluble sugars in raw root, while their changes were small during steaming. Therefore, soluble sugar content in cooked root of sweetpotato was determined by maltose content. Zheshu 13 had a good effect of saccharification after steaming, in which the content of soluble sugar and maltose were 179.64 mg·g^-1 and 138.44 mg·g^-1, respectively, significantly higher than the other 10 varieties. Hongpibaixin was a variety with high sugar in raw root, and the content of soluble sugar and fructose in raw root ranked first among the varieties tested.

Key words: sweetpotato, germplasm resources, soluble sugar content