Effects of structural modifications on some physical characteristics of exopolysaccharides from Lactococcus lactis

The relationship between the primary structure and the chain stiffness of exopolysaccharides (EPSs) and modified EPSs produced by two strains of Lactococcus lactis subsp. cremoris was investigated. The molar mass and radius of gyration of these exopolysaccharides were analyzed by multiangle static light scattering after size-exclusion chromatography. From these results and the chemical structure of the repeating units of the investigated EPSs, the Kuhn lengths could be calculated. We found that the initial Kuhn lengths of the two native EPSs are similar. Modification of the EPSs by removing parts of the side groups resulted in a decrease in both the absolute value and the normalized value of the Kuhn length. It is therefore concluded that partial removal of the side groups of these polysaccharides could make them less efficient as thickeners if no specific interaction with other components occurs.