High amylose

Starch digestion profiles from the HTA and the single-enzyme system were compared using standards of purified starch from standard maize, waxy maize, and high-amylose maize (purchased from Merck, formerly Sigma-Aldrich, Darmstadt, Germany), standard wheat starch (purchased from Merck, formerly Sigma-Aldrich, Darmstadt, Germany), and two high-amylose starches: sbeII and ssIIIa, previously characterized, respectively, by Corrado et al. and Fahy et al. [2 (link),21 (link)]. Starch samples were aliquoted to make 5.4 mg of starch/mL of PBS, and α-amylase activity was adjusted at 2 U/mL. The thermal treatment procedure was followed as described above for the starch digestibility HTA. Three runs were obtained for both protocols over different days. For each run, six replicates per starch sample were placed randomly in the 96-well plate for the HTA, and two replicates were used for the standard protocol. For each run, starch samples and enzyme solution were prepared in stock and aliquoted for use in both the HTA and single-enzyme system.

Waxy (0% amylose-100% amylopectin, S4126), normal (20% amylose-80% amylopectin, S6425), and high-amylose (70% amylose-30% amylopectin, S6430) corn starch powders were purchased from Sigma Aldrich (Steinheim, Germany). The Amylose content of the starch samples was confirmed by an enzymatic rapid assay kit (K-AMYL, Megazyme International, Wicklow, Ireland).