To investigate digestibility of cooked brown rice grain, changes in tissue structure of the grain with various milling degrees and starch hydrolysis during in vitro digestion were examined. The cooked grains treated with simulated saliva and gastric juice showed 6-15% starch hydrolysis, although structural changes of cellular tissue distribution at the surface of exposed endosperm were observed. The starch hydrolysis percentage increased after treatment with simulated pancreatic juice. The percentage for cooked brown grain was approximately 35%, which was less than the cooked milled grain, which showed 65% starch hydrolysis. Due to the microscopic observation for grain tissue structure during in vitro digestion, it was shown that the pericarp on the grain surface influences the starch hydrolysis of cooked grain.
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