To investigate the mechanism of whole-grain hull-less barley in regulating blood glucose in vitro, the content of β-glucan in hull-less barley and its factors were analyzed. In addition, the microstructure, particle size and pasting characteristics of hull-less barley were analyzed by using the scanning electron microscope, laser scanning confocal microscope, laser particle size analyzer and rapid viscosity analyzer, respectively. Subsequently, the impact of β-glucan, cellulose and protein on the digestion of starch in hull-less barley powder were evaluated. The results showed that removing β-glucan and cellulose from hull-less barley increased the starch digestibility, however, omitting gastric digestion could significantly limit the rate of starch digestion. Interestingly, the digestion of pure starch was not inhibited but improved slightly by adding a single β-glucan or protein. Similar results were observed in pasting viscosity. Moreover, compared with the content (5.60±0.06)% of β-glucan in whole hull-less barley, this value increased by 3.9% and 8.8% by removing protein and starch, respectively. The particle size of hull-less barley powder was reduced after the β-glucan or protein was removed. Besides, the microstructure also showed that β-glucan was located in the cell wall of hull-less barley, and the starch granules were distributed in the cell. These results indicated that the inhibitory effect of β-glucan on starch digestion depended on the intact structure of hull-less barley. Meanwhile, the activity of amylase was not retarded by β-glucan. Therefore, it is necessary to remain its intact structure as far as possible to ensure the physiological effect when processing the hull-less barley and its related products.
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