Structural characteristics determining starch digestibility in cooked rice complexed with an emulsion formulation

To evaluate the effects of structural characteristics on amylose-lipid complex (ALC) formation and the starch digestibility of cooked rice grains with the addition of 0, 5, 10, and 20 % emulsification formulation (EMF), both cooked rice (CR) grains with intact structural characteristics and CR slurries with their structural characteristics destroyed were examined. When EMF was added, the surface firmness, adhesiveness and adhesion of the CR grain changed. Depressions associated with ALC formation were observed on the surface of CR grains. The addition of more than 10 % EMF significantly suppressed starch hydrolysis in CR grains, while there was no significant difference in the starch digestibility of CR slurries, regardless of the amount of EMF. These results revealed that the structural characteristics of a layer like ALC on the CR grains suppressed starch digestibility and that once the structural characteristics were destroyed, the inhibitory effect of ALC on starch digestibility was lost.