Studies On Rheological Properties And Mechanisms Of Pectin From Ficus. Pumila L. Seeds

The Ficus pumila L. seeds, with much pectin on the surface, are good resources of pectin. As one kinds of natural extraction, pectin has various physiology functions, and has been used widely in recent years. In this study, the pectin from Ficus pumila L. seeds was prepared by low-temperature water extraction method. And the basic physiacochemical properties have been analyzed. In addition, the rheological property and mechaniasms of pectin affected by concentration,temperature, pH value,rotation treatment and Dynamic ultra-high pressure treatment were studied. The major contents in this paper were listed as follows:(1) The pectin extracted from the Ficus pumila L. seed by water was low-methoxy pectin, and the GA content is 89.3%, the average molecular weight was 960 kDa, determined by HPGPC. Rhamnose, Mannose, Galactose were contained in the structure of pectin at least.(2) Effects of concentration and temperature on rheological property of pectin solutions were studied. The pectin was pseudoplastic fluid. The viscosties increased with the increasing of concentration, but decreased with the overtime of heat treatment at 100℃.(3) Effects of pH value on rheology of pectin solutions were discussed, and mechaniasms were studied through the comparison of rheology of pH-treated samples and those treated samples that dialyzed. It's concluded that both of acid and alkali have complx impact on the viscosities of pectin solutions. Pectin chains would be disrupted with pH value 2.2 and 10.2, promoting the viscosity decreasing; While the rheological properties of pectin changed with pH value 3.0～9.3, attributed to the changing of intermolecular interactions and molecular conformations.(4) The effects of shear treatment on rheological property of pectin extracted from Ficus Pumila L. seeds have been studied, and mechaniasms were studied according to the comparisons of the rheological property of the various shear-treated pectin solutions and the restoration of each treated samples. It's shown that, the viscosity of 0.1% pectin solution decreased with increasing rotation speed treated the same time. At the speed above 20000 r/min, the structure was brokedown to a great extend. At the speed of 17500 r/min, the disrupted degree of the pectin structure rose with shear time, leading the viscosity value reducing.(5) Effects of Dynamic Ultra-high Pressure treatment on the rheological property of pectin extracted from Ficus Pumila L. seeds have been discussed. And the mechaniasms was studied by the restoration of viscosity of treated samples and the changing of molecular weight, and monosacchrides contents. When smples treated at 40 MPa, pectin was disrupted. The degree of pectin chains brokendown increased with the treated pressure, promoting viscosities decreased gradully. Side chains were brokendown at a great degree when samples treated at 160 MPa, and the molecular weight decreased to 75.5 kDa, the 160 Mpa-treated pcetin solution showed Newtonian behavior.