Effect of the degree of methyl esterification on the physicochemical properties and hypoglycaemic potential of pectin.

Pectins with degrees of methyl esterification (DM) ranging from 6 % to 96 % were prepared using alkali hydrolysis and acidified methanol for assessing their physicochemical properties and hypoglycaemic potential. Results showed that (1) pectin viscosity was jointly regulated by molecular weight, monosaccharide composition, and DM; (2) pectin with a DM of 96 % exhibited the highest thermal degradation peak temperature (282.17 °C), with the fastest and most complete degradation; and (3) pectin with a DM of 54 % showed the best inhibitory effects on α-amylase and α-glucosidase, with half-maximal inhibitory concentrations of 7.96 and 5.92 mg/mL, respectively. Moreover, pectin with a higher DM tended to exhibit noncompetitive-dominated inhibition, whereas pectin with a lower DM tended to show competitive-dominated inhibition. This study highlights the key role of DM in pectin properties and provides theoretical support for its applications.