Design of microbial polysaccharide films for food packaging

The overuse of synthetic non-biodegradable plastic packaging in the last decades turned into a serious global environmental problem, once recycling and energy recovery are not perfect solutions. To overcome this problem, efforts have been done by researchers around the world to use biodegradable biopolymers from renewable resources as food packaging materials. In this thesis, FucoPol, a microbial exopolysaccharide has been studied as a sustainable alternative and the following questions were raised: • Is it possible to produce films of FucoPol and which properties should be improved? • Which strategies may be applied to improve their behaviour, specially their barrier properties to gases and water vapour? • Is it possible to use FucoPol films as an alternative to synthetic plastics aiming their use as packaging material? This study shows that, FucoPol films offer good barrier properties to gases and biodegradability. Their weaker properties, low barrier properties to water, have been improved along the work, using two distinct strategies: formulation of bilayer films of FucoPol and chitosan and use of different coatings techniques in FucoPol films. The results have shown that, it is possible to improve FucoPol films properties, namely the barrier properties to gases and water vapour, and resistance to liquid water. FucoPol combined with chitosan as a bilayer film was used for walnuts packaging and it was possible to verify that it can protect food susceptible to lipid oxidation as effectively as synthetic materials