Mechanism of viscosity reduction of okra pectic polysaccharide by ascorbic acid

In this work, effects of ascorbic acid (AH2) treatment on the viscosity and structural properties of okra pectic polysaccharide (OPP) and its mechanism were investigated. Results showed that AH2 could decrease the apparent viscosity of OPP, and the reducing ability was promoted by high temperature and the addition of Fe2+, Cu2+ or H2O2. The molecular weight was significantly decreased with increasing AH2 concentration, but it had little effects on the monosaccharide composition, glycosidic linkages, infrared characteristics, and morphology of OPP after AH2 incubation. Hydroxyl radicals were generated during the incubation, which can be activated by introducing Fe2+, Cu2+ or H2O2. In summary, the viscosity reduction of OPP induced by AH2 was related to the formation of hydroxyl radicals. The present study provides some recommendations for the application of OPP in food and other products containing AH2.