Abstract
Biodegradable films based on starch, sodium caseinate, glycerol and lipids (oleic acid and/or a-tocopherol)
were obtained and evaluated in terms of microstructure, mechanical behaviour, barrier and optical
properties and antioxidant capacity. The effect of film storage time on these properties was also analysed.
The lipid incorporation provoked phase separation due to the different interaction between each polymer
and lipids, although structural rearrangement of components during storage could be deduced from the
change in mechanical behaviour. After storage, all films showed similar mechanical properties, but lipid
containing films were more stretchable. Lipid addition did not induce a notable decreased in water
vapour permeability of the films, but oxygen permeability highly increased when they contained oleic
acid. All films were highly transparent, with very small differences among formulations, although their
gloss values increased when lipids were added. The incorporation of a-tocopherol greatly increased
the antioxidant capacity of the films which affected oxygen permeability.
