Characterization of a biodegradable starch based film. Application on the preservation of fresh spinach

Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia - UL

The goal of the present study was the characterization of a biodegradable thermoplastic starch based wrap film (TPS), produced from Mater-Bi®, and its application on the preservation of ready prepared fresh-cut spinach, in parallel with the non-biodegradable polyvinyl chloride (PVC) wrap film. The TPS-based film presented a similar vapour adsorption (< 5%, dry basis) to the PVC film. In addition, the carbon dioxide and oxygen permeability was in the same range (TPS-based: PCO2 =34.6x10-17-76.1x10-17mol.m/m2sPa, PO2 =3.41x10-17 – 5.71x10-17 mol.m/m2sPa; PVC: PCO2 = 34.5x1017 – 62.8x10-17mol.m/m2sPa, PO2 = 3.03x10-17 – 6.21x10-17 mol.m/m2sPa), and was not significantly affected by the relative humidity. The major differences detected were in what concerns water vapour permeability, (0.9x10-12 - 1.27x10-12 mol.m/m2sPa and 3.64x10-12 – 4.43x10-12 mol.m/m2sPa for TPSbased and PVC film) and strain at break (5.7 times higher for TPS-based under extension tests). TPSbased film showed a better transparency for white colour, although for green, yellow and red it was the PVC having better results. Both films revealed to have a similar performance in fresh-cut spinach preservation. The major difference was detected on the preventing weight loss, as PVC film showed to be more effective than TPS-based film due to its higher water vapour barrier. Based on the results obtained it can be concluded that the tested thermoplastic starch based wrap film is a strong substitute, ecological, to conventional PVC-based film