Antioxidant activity of low molecular weight alginate produced by thermal treatment

• The low molecular weight alginates were produced by heat treatment.
• Heat-treated alginate exhibited better antioxidant activity than alginate polymer.
• Antioxidant properties depend on the concentration and treatment time.
• Raised antioxidant activity is probably due to formation of more functional groups.
• These products will be useful for food industrial and biomedical applications.

By definition, antioxidants are molecules that inhibit the oxidation of other molecules. Therefore, such compounds have very important clinical roles. In this study alginate polymer was depolymerized by heat treatment. The resulting low molecular weight alginates were investigated by UV–visible spectroscopy, Viscometry, Dynamic light scattering and FT-IR spectroscopy techniques. Antioxidant properties of these heat products were studied by ABTS and superoxide radical scavenging assays. Results showed that heating caused breaks in the polymer chain and so generation of low molecular weight alginates. Antioxidant measurements confirmed antioxidant activity of alginate increased upon a decrease in molecular weight. Therefore, low molecular weight alginate produced by heating could be considered as a stronger antioxidant than alginate polymer. These products could be useful for industrial and biomedical applications.