Effect of endogenous protein on starch before and after post-harvest ripening of corn: Structure, pasting, rheological and digestive properties.

This work revealed the effects of endogenous proteins on the structural, physicochemical, and digestive properties of starch in corn before and after ripening and explored the binding mechanism of proteins with starch. The microstructure showed that the postharvest ripening process resulted in a thinning of the protein layer on the surface of starch particle. After the removal of protein, the uniformity of the sample surface increased, with tiny pores. The proportion of double helix structure of starch were significantly reduced, while the proportion of amorphous structure and the thickness (d) of the amorphous region were significantly increased. The gelatinization enthalpy, gelatinization viscosity value, consistency coefficient, elasticity, and rapid digestibility of starch (RDS) were all significantly increased. Due to the weakening of the interaction between starch (including amylose and amylopectin) and protein in post-ripened corn, the effect of protein removal on the structure and properties of unripened samples was more significant.