Particle size-starch-protein digestibility relationships in cowpea (Vigna unguiculata)

► In vitro digestion in milled cowpea of different particle sizes was investigated. ► A modified first-order kinetic model described the starch and protein digestograms. ► Rate of protein digestion was about 100× faster than rate of starch digestion. ► Rate of starch digestion was inversely related to the square of particle size. ► Rate of protein digestion was not related to particle size of hammer-milled cowpea.