Use of the brown seaweed Sargassum latifolium in the design of alginate-fucoidan based films with natural antioxidant properties and kinetic modeling of moisture sorption and polyphenolic release

Alginate and fucoidan are unique polysaccharides present in brown algae and widely used in food and medical technologies. Alginate and fucoidan were sequentially extracted from Sargassum latifolium and used for the preparation of alginate and alginate-fucoidan blend films with or without Ca-crosslinking. The incorporation of fucoidan and Ca2+ decreased water solubility, but increased film thickness, water vapor permeability and oxygen permeability. The films showed good properties against ultraviolet light, however, incorporation of fucoidan and/or Ca2+ decreased the color parameter L* value and increased the a* and b* values of the films. The interaction of Ca2+ and fucoidan with alginate was investigated using FTIR analysis which confirmed the presence of hydrogen bonded interaction. Kinetics of moisture sorption and polyphenol release exhibited a good fit to Peleg's model. Ca2+ crosslinking decreased initial moisture sorption and increased the maximum sorption capacity of the films. Additionally, the water vapor diffusion and polyphenol release were expressed in terms of effective diffusion coefficient based on simplified Fick's law. The developed films showed good antioxidant properties as measured by total antioxidant assay, ferric reducing antioxidant power and hydroxyl radical scavenging activity. Both film type and the type of the food simulant markedly affected the polyphenol release and the antioxidant activity of the films. (C) 2018 Elsevier Ltd. All rights reserved.