Characterization of biodegradable films prepared with hake proteins and thyme oil

Hake protein biodegradable films containing different thyme oil levels (0.025, 0.05, 0.1 and 0.25 ml oil/g protein) were prepared and their physical, mechanical and antioxidant properties were studied. Dried proteins were solubilized at pH 11 with NaOH and glycerol (59% of protein content) was added as plasticizer. The addition of thyme oil levels reduced both the film thickness and water vapor permeability. Films were homogeneous and transparent with a yellowish color. The optical properties of films were not generally affected by the thyme oil addition. Any clear trend between the mechanical properties of biodegradable films and thyme oil added was observed. Hake protein films exhibited some antioxidant activity, which was improved by the addition of 0.25 ml of thyme oil/g of protein. (C) 2011 Elsevier Ltd. All rights reserved.