Abstract:The effect of the pressure from high-pressure homogenization on granule morphology, polarization cross, grain diameter, crystal property and in vitro digestibility of Dioscorea opposita starch were investigated in this study. The results showed that the surface of Dioscorea opposita starch granule was damaged and the intensity of polarization cross was reduced by high-pressure homogenization. The particle size decreased initially and increased subsequently with increasing homogenization pressure. The minimum (25.16 μm) and maximum sizes (27.81 μm) were found at pressures of 40 MPa and 100 MPa, respectively. The C-type crystal structure was not changed, while the degree of crystallinity decreased from 26.45% to 21.00%. The widths and intensities of the infrared (IR) absorption peaks at 3233.42, 1164.01, 1081.90, 1050.27, and 1015.81 cm-1 decreased. The degree of order in the starch was also reduced to some extent. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) in the native starch were 11.32%, 7.00%, and 81.68%, respectively. After the homogenization treatment at 100 MPa, the contents of RDS and SDS were increased to 20.63% and 10.41%, respectively, while the RS content was reduced to 68.96%. The results suggested that high-pressure homogenization reduced the degree of crystallinity in the starch, which results in reduced resistance to enzymatic digestion and enhanced digestibility. This trend was more apparent at higher pressure.
