Effect of glutenin and gliadin modified by protein-glutaminase on retrogradation properties and digestibility of potato starch.

The glutenin (Glu) and gliadin (Gli) were modified by protein-glutaminase (PG) to obtain soluble glutenin (PG-Glu) and gliadin (PG-Gli), and PG-Glu or PG-Gli was added to potato starch (PS) according to different amounts (0.5%, 1.0%, and 1.5%, based on dry starch weight, w/w) to explore the effect of modified proteins on the retrogradation behavior and digestibility of PS. The results showed that the long-term retrogradation of PS was accelerated by the addition of PG-Glu or PG-Gli. The addition of PG-Glu or PG-Gli led to an increase in hydrogen bonds within starch molecules and induced a significant increase in resistant starch content. The hydrolysis kinetic parameters, C and K, both decreased with the increasing level of modified protein, indicating the deceleration of hydrolysis rate by the addition of PG-Glu or PG-Gli. In summary, the addition of PG-Glu or PG-Gli could promote the retrogradation of PS and mitigate the digestion of starch.