Studies on in vitro antioxidant potentials and characterization of κ-carrageenan based biodegradable film from red algae, Hypnea valentiae (Turner) Montagne, 1841

Seaweeds are a rich source of various bioactive compounds and metabolites. In this study, sulfated polysaccharide, kappa-carrageenan has been isolated from red algae, Hypnea valentiae, and developed biodegradable film with the addition of plasticizers, sorbitol and polyethylene glycol (PEG 4000) at varying concentrations of carrageenan (1%, 5% and 7% Carr). The biodegradable film exhibited excellent mechanical properties with increasing carrageenan concentration. The 5% Carr film showed improved water barrier properties, high water contact angle (hydrophobicity), high tensile strength (11.38 MPa) and elongation at break (23.27%) which imparts rigidity and flexibility to the film. The results of FTIR and SEM images revealed that the plasticizers and polysaccharides have been blended properly. Since seaweeds are natural antioxidants the kappa-carrageenan based biodegradable films displayed strong radical scavenging activity. The 7% Carr film exhibited 86% of radical scavenging activity in ABTS assay and 5% Carr showed 80% of scavenging activity. The biodegradable films displayed efficient antibacterial activity against gram-negative bacteria, E. coli and gram-positive bacteria, B. subtilis. The developed films exhibited excellent biodegradability, the films samples degraded completely within 84 days of soil burial. The kappa-carrageenan based biodegradable film (5% Carr) from red algae, H. valentiae better serves as a versatile food packaging material.