Development and characterization of edible films from mixtures of κ-carrageenan, ι-carrageenan, and alginate

• Films were prepared from κ-carrageenan, ι-carrageenan and alginate.
• κ-carrageenan was the component which most improved barrier and tensile properties.
• ι-carrageenan was the component which most impaired such properties.
• Alginate based films presented the highest uniformity and transparency.
• ι-carrageenan-containing films presented aggregates and high opacity.

Different proportions of κ-carrageenan, ι-carrageenan and alginate have been used to prepare glycerol-plasticized edible films, according to a simplex-centroid mixture design. κ-carrageenan was the component which most improved the moisture barrier and overall tensile properties (except elongation), while ι-carrageenan was the component which most impaired those properties. Alginate was the component which most favored film uniformity (as observed by SEM images) and transparency, while ι-carrageenan presented a high density of clusters and, accordingly, the highest effect on opacity. Aggregates in ι-carrageenan probably resulted from an early gelation induced either by the eventual presence of salt contaminants or by cooling the film dispersions to temperatures below 45 °C (coil-helix transition temperature of ι-carrageenan) upon casting. Those aggregates resulted in impaired physical (tensile, barrier, and optical) properties of films containing ι-carrageenan.

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