Abstract: In the present study, pre-digested puffed rice flours with different dextrose equivalent (DE) values were prepared by using enzymatic pretreatment and extrusion, and their gelatinization characteristics, physicochemical and structural properties were analyzed. The results showed that compared with puffed rice flour, the water solubility index of pre-digested puffed rice flour increased by up to about 1.5 times with an increase in DE value, the water absorption index decreased by up to 76%, the slip angle decreased, the Carr index and Hausner ratio increased, and the reconstitutability and fluidity improved obviously. Moreover, the final viscosity and setback value of pre-digested puffed rice flour decreased with increasing DE value, decreasing by up to 37.79% and 94.87%, respectively. Moreover, after enzymatic pretreatment and extrusion, the soluble protein content of pre-digested puffed rice flour decreased, and the content of rapidly digestible starch increased significantly, while the secondary structure of protein and the crystalline structure of starch did not change significantly. The results provide a theoretical basis for the application of pre-digested puffed rice flour instead of maltodextrin in foods for special medical purpose.

Key words: puffed rice flour; enzymatic pretreatment; extrusion; physicochemical properties; structural properties