Microcalorimetric investigation of amylopectin branching and the content of amylose in potato starches

Abstract

Hydroxyethylated starches are of particular interest for applications in infusion therapy because of their high volemic effect. The duration of this effect depends on the circulation time of the drug in the blood, i.e., the volume of circulating blood increases with an increase in the concentration, molecular weight and degree of polymer substitution. It is known that hydroxyethylated starches have a wide range of molecular weight and degree of substitution. This allows their solutions to circulate for a long time (up to 10 hours) in the bloodstream without leakage of the active substance into the interstitium of vital organs. The dependence of the melting point of the crystalline starch lamella on the number of glucose residues can be described using the modified Fox - Loshaek ratio, which takes into account the degree of branching of amylopectin molecules and the content of amylose in starch. We proposed an analytical expression for the evaluation of the degree of branching of amylopectin from potato starch based on microcalorimetric data. The proposed methodology allows the genotypes of potatoes with the highest degree of amylopectin branching and a minimum quantity of amylose in starch to be selected. Starches of such potato varieties can be used in the blood plasma substitutes production - hydroxyethylated starches that have good pharmacodynamic properties. Within the developed approach, it is possible to determine the effect of the degree of substitution on the thermodynamic properties of the studied starches through a change in the melting temperature of the lamella, Tm, hence estimating the main pharmacodynamic parameters of substituted starches.