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.