Effects of composition, starch structural orders, and kernel structure on starch in vitro digestion of highland barley

In this study, the widely used varieties in China were selected to explore the low starch digestive properties of highland barley from three aspects of composition, starch structural orders, and kernel structure. Two digestive systems were constructed, with highland barley in flour and chyme forms, to investigate the contribution of these inherent properties to starch digestion under different physical forms. Compared with white and black highland barley, blue varieties showed poor chemical composition, lower starch crystallinity, and higher short-range structural order degree, but the starch digestibility as flour was only slightly higher. All varieties of chyme demonstrated lower starch digestibility compared to flour; however, blue highland barley chyme showed much lower starch digestibility than other chyme. Furthermore, kernel structural analysis showed that the blue highland barley kernel structure effectively inhibited digestion. These results indicated that the kernel structure had a critical influence on the starch digestibility of highland barley.