The Role of Chain Structures on Enzymatic Hydrolysis of Potato and Sweet Potato Amylopectins

The relationships between the chain length distributions and enzymatic hydrolysis of potato amylopectin (PA) and sweet potato amylopectin (SPA) are studied to illustrate the effect of the internal branch structure of amylopectins on the digestibility of starches. The results show that SPA is more slowly hydrolyzed than PA due to the shorter internal chain length and a higher number of short chains with a higher density of branch leading to a more compact structure. Both PA and SPA display two phases in logarithm of slope plots, and PA has a higher rate constant k value than SPA. Using α -amylase alone, a small amount of glucose is produced from PA and SPA, the primary products being maltose, maltotriose, and maltotetraose. Together with glucoamylase, glucose released from PA and SPA is significantly enhanced. Glucose release is about 3–10 times more than that released by α -amylase alone. The digestible properties of starch and starch-based products may be effectively regulated by controlling short:long B-chains, density of branch, total chain length, and internal chain length of amylopectins.