Comparison of in vitro starch digestibility and structure of matcha-fortified starch vermicelli from different...

In a study to explore the utilization of polyphenols in complex digestive systems, starch-based vermicelli was employed as the carrier and matcha (MT) was used as the source of polyphenols. Four percent MT was extruded with A-, B-, and C-type starch of rice, sweet potato, and mung bean to prepared starch vermicelli rice starch vermicelli (RSV), sweet potato starch vermicelli (SPSV), and mung bean starch vermicelli (MBSV), respectively. The multi-scale structure of starch, the digestive kinetics of starch, and the bioaccessibility of polyphenols during in vitro digestion were monitored.

Matcha did not change the crystal configuration of vermicelli, but increased the relative crystallinity of RSV. Vermicelli with MT possessed a more uniform structure, and the polydispersity index decreased from 3.85-4.89 to 2.56-3.69. However, these structural changes made only a limited contribution to delaying digestion. The detection of polyphenols during digestion revealed that the release of most polyphenols was accomplished in the first 20 min of digestion. The release amount was in the order RSV + MT > MBSV + MT > SPSV + MT, and reached 4.81-5.45 mg GAE g^-1 . Correspondingly, the activity of digestive enzyme decreased in the order RSV + MT < MBSV + MT < SPSV + MT. Consequently, MT significantly (P < 0.05) reduced the digestive rate of vermicelli, and the rapidly digested starch and predicted glycemic index of RSV + MT decreased from 71.28% to 56.31% and from 74.68 to 62.86, respectively. The released polyphenols were also the main source of the strong antioxidant capacity of vermicelli with MT.

These results provided a theoretical basis for using polyphenols to pursue healthy starch-based food. © 2023 Society of Chemical Industry.