Radiation effects in pectins

Abstract

Irradiation of pectins by γ-rays causes the decomposition of molecules, which is observed as an extensive decrease of the specific viscosity of the solutions. The molecular weight also decreases by a factor in the range of 10 2. The decomposition is intensified when solutions of pectin in water are irradiated. In that case, considerable de-esterification of carboxyl groups is also found. Solid pectins are more stable. The difference may be due to the radiolytic products of water. The irradiation of pectins increases their thermal instability, which is observed as a decrease of the activation energy for thermal degradation. The comparison of activation energies with values for other compounds with similar polysaccharide structures, suggests that in all such materials the mechanisms for thermal decomposition and for radiolysis are very similar. The results indicate a considerable sensitivity of pectins to γ-irradiation. This suggests that special precautions are required if it is desired to treat with γ-rays natural products, containing both pectins and water.