Changes in the molecular weight distribution of three commercial pectins after valve homogenization

Molecular changes after valve homogenization of three commercial pectin samples were studied by linear mix permeation chromatography coupled with multi-angle light scattering detection. The flow behavior of homogenized pectins was also determined. On the one hand, homogenization at 124 MPa had a significant effect on molecular weight distribution and molecular weight averages of high methoxyl pectin samples. On the other hand, no changes occurred in the apparent viscosity of the diluted pectin solutions after homogenization at 17 MPa, and only one of the pectins analyzed showed an effect of high pressure (124 MPa) on viscosity. While the apparent viscosity of pectin with a wide molecular size distribution (large polydispersity) did not change upon pressure treatment, one of the studied pectin, characterized by a sharp molecular weight distribution, showed increased polydispersity and a significant change in flow behavior after treatment at 124 MPa. Results demonstrated that molecular changes may occur upon valve homogenization, and that the polydispersity of molecular weight distribution may hinder an accurate estimation of such changes.