Assessing the suitability of polylactic acid flexible films for high pressure pasteurization and sterilization of packaged foodstuff

To the aim of assessing the suitability of PLA film for HP treatment of packaged food, the effects of treatments have been analyzed in terms of structural/morphological changes (i.e. crystallinity, density, orientation of PLA film) and of thermodynamics and functional properties (i.e. melting and glass transition temperature, permeability and solubility of gases and of water vapor). It has been found that HP pasteurization does not affect to a significant extent any structural and functional property of the treated material relevant for food packaging applications. Conversely, HP sterilization promotes the hydrolysis of the material accompanied by an increase of crystallinity of the film and a decrease of density of the amorphous phase related to the temperature/pressure history. These effects determine an unacceptable embrittlement and opacification of the material that makes it unsuitable for HP sterilization applications. (c) 2012 Elsevier Ltd. All rights reserved.