Potential inhibitors of the ascorbate-induced β-glucan degradation

The effects of several radical scavengers and oxidation inhibitors on ascorbate-induced hydroxyl radicals, responsible for β-glucan oxidation, were studied by ESR spin trapping. The most effective compounds in decreasing the radical formation in β-glucan solutions were phytic acid, sulphite and enzymes (catalase and superoxide dismutase). Also phenolic compounds, sugars and organic acids demonstrated a high radical-scavenging capacity, but they showed more variation within the group. The compounds showing a very high antioxidant capacity in 100 min monitoring were chosen for the viscosity measurements. Though able to reduce radical formation, phytic acid, potassium bisulphite and citric acid were inefficient in inhibiting viscosity loss. Sucrose, phenylalanine and hydroxybenzoic acid were able to significantly slow the viscosity decrease in a longer time frame. Catalase completely inhibited viscosity loss and thereby β-glucan degradation. These results show that the oxidative cleavage of β-glucan can be inhibited by radical scavengers and other oxidation inhibitors; however the effects are very much dependent on the compound, concentration and time of oxidation.