Resistant starch and other dietary fiber components in tubers from a high-amylose potato.

Tubers from a genetically modified high-amylose line T-2012 and its parental potato cultivar Dinamo were analyzed for resistant starch (RS) and dietary fiber (DF) after cooking and cold storage. For uncooked potatoes, the high-amylose tubers (30% of dry matter, DM) had much lower RS than the parent tubers (56% of DM). However, after cooking, the high-amylose tubers gave more RS (13% of DM) than the parent (4% of DM), and the RS level increased further to about 20% of DM after 1 day of cold storage. The altered RS content was attributable to changes in amylose content, starch granule structure, and amylopectin structure induced by the genetic modification. The high-amylose tubers also contained more DF (10-14% of DM) than the parent (5-7% of DM). Furthermore, cell wall composition was indirectly affected by the genetic modification, giving more cellulose and less pectin in the high-amylose tubers than the parent.