Exploring the underlying mechanisms on starch restricted swelling-induced reduction in digestion rate of buckwheat noodles

Abstract

To elucidate the slower digestion rate of buckwheat starch in noodles-matrix, the digestion kinetics of Tartary (TBN) and common (CBN) buckwheat starch reconstituted noodles as well as wheat starch reconstituted noodles (WSN) were compared using a simulated oral-gastric-intestinal in vitro digestion. The swelling degree of starch in cooked noodles can be expressed by quantitative analysis of microstructure. The digestion rate of WSN was 2.3–2.9 times higher as compared to CBN and TBN. The swelling degree of starch in CBN and TBN was restricted due to their denser structure, which led to the reduction of the contact area between starch molecules and amylase. Additionally, the stronger water retention ability and higher cohesiveness of CBN and TBN could hinder the water migration, and ultimately affect the accessibility of enzymes. These results demonstrated that the restricted swelling of starch in CBN and TBN during cooking was the important reason for their slower digestibility.