Effects of Explosion Puffing on the Composition, Structure, and Functional Characteristics of Starch and Protein in Grains

The effects of explosion puffing on the composition, structure, and functional characteristics of starch and protein in millet, barley, black rice, rice, glutinous rice, and wheat were investigated. The results showed that the microstructure of puffed grains turned from dense and compact into sparse and porous. The protein in puffed grains was degraded into soluble polypeptide and amino acid, the α-helix and β-turn proportion in the protein of six grains decreased, while the β-sheet proportion protein of six grains increased significantly. Before and after being puffed, the contents of rapid digested starch, slowly digested starch, and resistant starch in the starch of six grains changed obviously, and the amylose-to-amylopectin ratios of all grains increased significantly. Meanwhile, the content of soluble sugar was increasing, and glucose and maltose were the main sugars in puffed grains. Results of X-ray diffraction indicated that the crystal structure of starch in puffed grains was changed from A to V, and at the same time, the crystallinity decreased obviously. Therefore, explosion puffing could contribute to the degradation of protein and starch of grains into small molecular substances, which could improve the bioavailability of grains.