Elevated CO2 promotes faster wheat starch digestion through coordinated changes in starch and protein.

Rising atmospheric CO2 affects the nutritional functionality of wheat grains, but how coordinated changes in starch and protein under elevated CO2 (eCO2) contribute to starch digestibility remains unclear. Winter wheat was grown under ambient (415 ppm) and eCO2 (600 ppm) to investigate eCO2 effects on grain quality traits and in vitro starch digestion kinetics. Results indicated that eCO2 generally increased amylose content, the proportion of B-type starch granules, the enthalpy of gelatinization and the relative crystallinity of wheat grain starch, while decreasing R1047/1022 and the proportion of DP 13-24 chains. Meanwhile, eCO2 reduced glutenin content and gluten index in wheat flour. These coordinated changes were accompanied by a higher digestion rate constant (k) and lower resistant starch in wheat flour. These findings indicate that changes in starch physicochemical and protein properties contribute to accelerated starch digestion and inform the development of wheat-based starch foods under future high CO2 scenarios.