Role of sucrose in pectin gelation: Static and dynamic light scattering experiments

We report data on static and dynamic light scattering of semidilute solutions of high methoxyl pectin in the presence of different amounts of sucrose, ranging from few % (w/w) up to a value just below the threshold required for gel formation. The apparent gyration radius of the pectin is found to slightly increase with sucrose concentration while the mean relaxation time displays a diverging behavior, strongly correlated with the increase of the solvent bulk viscosity. The dynamic behavior on approaching the condition required for gelation exhibits features typical of a glass transition, providing new insight into the role of sucrose in promoting the gelation of pectin.