Antioxidant and Prebiotic Properties of γ-Radiation Processed Alginate

Background: Recently, many carbohydrates and their derivatives are being investigated for bioactivity. In the present study, we aimed at developing a novel antioxidant and prebiotic component by radiation processing of sodium alginate. Method: Gamma irradiated (0.5 to 40 kGy) aqueous solution of sodium alginate was characterised by UV-visible, fluorescence, Fourier transform infrared (FT-IR) spectroscopy and thin layer chromatography (TLC) analysis. Antioxidant potential of processed alginate was determined using different in vitro assays and prebiotic activity was evaluated by co-culturing of E. coli and Lactobacillus plantarum. Observation: Approximately, 50% of superoxide radicals and 75% of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals were scavenged by oligomers at concentrations of 1 mg/ml and 5 mg/ml, respectively. The ability to chelate iron and to inhibit the oxidation of β-carotene was not affected. Radiation processing improved the prebiotic activities as seen by enhanced cell number of L. plantarum by one log and reduction in E. coli count. The efficiency in reducing E. coli depended directly on the absorbed dose. Conclusion: Results suggest that radiation processing of alginate is a practical method for improving its antioxidant and prebiotic activity and thus improving the applicability of alginate in nutraceutical industries.