Fourier transform infrared microspectroscopic study of the chemical microstructure of corn and oat flour-based extrudates

The spatial distribution of starch, protein, and lipid domains (chemical microstructure) in corn and oat flour-based extrudates was investigated in 8 μm thick cross-sections of the products by FTIR-microspectroscopy mapping experiments. The results reveal an even starch distribution in all extrudates investigated confirming that starch forms a continuous phase in cereal-based extrudates. Proteins were the least evenly distributed among the three components. Also, small, protein rich domains of 70 μm diameter were detected in the microstructure of the extrudates. Starch and protein distributions were always inversely related to each other. The lipids in oat flour-based extrudates were less evenly distributed than the starch, but more evenly than the proteins. Lipid distribution was neither correlated with starch nor with protein distribution.