Effects of endogenous and exogenous corn protein and its hydrolysates on the structural change and starch digestibility of fried corn starch

Summary Frying could lead to deformation of starch granules and significant reduction in their internal crystalline structure. All of these changes could lead to rapid digestion of fried starch. The addition of corn protein and its hydrolysate to samples prior to frying can reduce the structural change of the granules and also increase their crystallinity and thermostability. Besides, both corn protein and its hydrolysates showed potent abilities in mitigating starch digestion. The fractions of slowly digestible starch and resistant starch increased significantly after the addition of corn protein or its hydrolysate. Meanwhile, the effect of removal of endogenous protein on fried starch was also examined. The results showed that, after removing the protein, starch granules were severely disintegrated during frying; most importantly, the digestibility of starch was increased significantly. The mitigating effect on corn starch digestion could be attributed to structural changes in the ordered structure and suppression of enzyme activities.