Effect of alginate and λ-carrageenan on tensile properties and water vapour permeability of sodium caseinate-lipid based films

摘要

Tensile properties and water vapour permeability (WVP) of edible films obtained from blends of sodium caseinate, polysaccharides (alginate or λ-carrageenan) and lipids (oleic acid and beeswax) were investigated. In lipid-free films with plasticizer, polysaccharides improved the tensile properties of films, although water vapour permeability values increased; this effect being more notable for λ-carrageenan and dependent on the polysaccharide concentration. Lipid mixture incorporation in the film resulted in more flexible films as compared to those prepared with pure beeswax, but the increase in beeswax contents implied a decrease in WVP. When lipids (oleic acid and beeswax) were present λ.-carrageenan modify lightly the films properties, but the addition of alginate produce less flexible, less stretchable and more permeable films. In the absence of plasticizer, λ-carrageenan promoted stiffness and resistance to elongation of the caseinate films and reduce their WVP at low ratio of BW in the lipid mixtures (below 50%), showing the opposite effect at greater BW ratio.