Macromolecular composition of inulins of various origin in concentrated solution

Abstract

A research study into the molecular weight distribution of inulins of various origin was conducted to elucidate the mechanism of their self-organization in concentrated solutions. Using the conventional turbidimetric titration method based on integral and differential molecular weight distribution curves, the following inulin samples were examined: commercial girasol (A), experimental girasol (B) and experimental chicory (C). Inulin A and B samples were found to include three macromolecular fractions (isoforms), each exhibiting a narrow molecular weight distribution. An increase in inulin concentration in the solution leads to selforganization of macromolecules, resulting in a more turbid solution at the point of maximum and the appearance of new isoforms. An increase in polymer concentration in inulin A leads to an increase in the aggregates of isoforms 3 and 5. Conversely, in inulin B, aggregates dissolve making isoforms convert from high- to low molecular weights. In inulin C, all four inulin isoforms are clearly represented. An analysis of the interaction of macromolecules in a concentrated solution confirmed the applicability of turbidimetric titration for determining the molecular weight distribution of polymers, along with such costly procedures, as highperformance size exclusion liquid chromatography, ultracentrifugation and light scattering. Research into the properties of unique inulins may significantly expand the range of their practical application.