Effects of Dynamic High-pressure Microfluidization on the Physicochemical Properties and Structure of Low-Methoxyl Pectin

In this study, the effects of dynamic high-pressure microfluidization(DHPM) on the physicochemical properties and structure of low-methoxyl pectin(LMP) from Ficus pumila L. seeds were studied. LMP was treated under different DHPM pressures(0~160 MPa) and cycles(1~9 times), and the structure and physicochemical properties of DHPM-treated LMP were comprehensively evaluated using various indicators such as molecular weight, intrinsic viscosity, particle size, reducing sugar level, Fourier transform infrared(FT-IR) spectra, and surface morphology. The results showed that with increasing DHPM pressures and cycles, the molecular weight, intrinsic viscosity, and particle size of LMP decreased, whereas the amount of reducing sugars increased. At the same time, the surface topography of LMP changed from a foliated structure to a filament structure, indicating that LMP degraded during DHPM. The degradation of LMP mainly resulted from the rupture of the glycosidic bond by DHPM mechanical forces. The FT-IR spectra of DHPM-treated pectin had features similar to those of untreated pectin; however, the intensity of the absorption peak at 1744.8 cm-1(C=O) increased with increasing DHPM pressures. The experimental determination of the methoxyl group and double bond contents revealed that demethoxylation and β-elimination did not occur during DHPM.