Resistant starch formation in temperature treated potato starches varying in amylose/amylopectin ratio

Two genetically modified potato starches derived from the same mother line (64%, 1% and 23% amylose, respectively) were used to study the bioavailability after various heat treatments. The conditions for the treatments were of minor importance for resistant starch (RS) formation and hydrolysis results, as compared to the proportion of amylose. A high amylose content gave lower hydrolysis index (HI) and higher amounts of RS than starches with less amylose. Retrograded amylopectin contributed to a decreased HI, although only the high amylose line showed sufficient reduction in predicted glycaemic indices (GI). The line with high amylose content contained 25–30% RS vs. in the range of 0–5% for the other starches. Results could neither be explained by the presence of intact granules, nor by the content of retrograded amylose. Therefore, a synergistic effect between the starch components was suggested to affect the RS and starch hydrolysis.