Generating slow digestibility in cooked potatoes by modulating starch accessibility to α-amylase and mucosal α-glucosidase to different levels

Abstract

Health issues associated with overconsuming rapidly digestible glycemic carbohydrates continue to be prevalent globally. Transforming starch digestion from a hyperglycemic response to a sustained dietary glucose profile is an ideal digestion scenario. Digesting starch to glucose requires α-amylase (AMY) and mucosal α-glucosidase (m-AG). AMY can quickly break down starch molecules, and m-AG functions as the gatekeeper of dietary glucose production. In this study of cooked potatoes, we hypothesize that slow glucogenesis from starch can be achieved by modulating the accessibility of AMY and m-AG to starch to different levels by modifying cell wall permeability by promoting cross-linking of calcium with endogenous pectins. Raw potato cubes were blanched with 0–500 mg/L calcium solution, followed by steaming. Fully cooked potatoes with the pre-treatment had up to 41% and 99% reduction of the permeability for dextran probes of 20 kDa and 70 kDa, respectively, and a non-detectable permeability of 150 kDa dextran. Permeability data indicated a decrease in the accessibility of AMY and a complete restriction of m-AG to access starch in cells supported by data on starch susceptibility to both AMY and m-AG separately. In vitro stimulated gastrointestinal digestion data demonstrated a blunt glucose profile with a reduction of RDS from 80% to 46% and an increase of SDS from 12% to 37%. By modulating starch accessibility to AMY and m-AG to different extents, cooked potatoes were fully digested with a slow glucose-released profile. The modification was a pre-treatment, and modified potatoes can be processed into potato foods, such as french fries, mashed potatoes, and others.