PACKAGING TECHNOLOGY AND SCIENCE Packag. Technol. Sci. 2008; 21: 297–308 Published online 5 March 2008 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/pts.807 Mechanical and Thermal Behaviour of Flexible Food Packaging Polymeric Films Materials under High Pressure/Temperature Treatments By M J Galotto, 1 * P. A Ulloa, 1 D. Hernández, 1 F. Fernández-Martín, 2 R. Gavara 3 and A. Guarda 1 1 LABEN-CHILE, Laboratorio de Envases, Dpto de Ciencia y Tecnología de Alimentos, Facultad Tecnológica, Edificio Alimentos, USACH, Obispo Umaña 050, Santiago, Chile. Laboratorio de Envases. Facultad Tecnológica. USACH 2 Instituto del Frío (CSIC). Ciudad Universitaria, 28040-Madrid, Spain 3 Instituto de Agroquímica y Tecnología de Alimentos. Consejo Superior de Investigaciones Científicas. Burjassot, Valencia, Spain The effect of high-pressure processing on mechanical and thermal properties of four complex packaging materials (polyethylene/ethylene vinyl alcohol/ polyethylene: PE/EVOH/PE; metallized polyester/polyethylene: PETmet/PE; polyester/ polyethylene: PET/PE; polypropylene SiOx recovered: PPSiOx) was studied. Pouches of the different materials containing distilled water or olive oil as food simulants, as well as empty ones, were subjected to 400 MPa for 30 min, at temperatures of 20 or 60°C. Delamination and wrinkling were a general consequence of the high-pressure processing of multilayer polymeric systems. However, no significant changes were observed regarding the mechanical properties of PE containing laminates after pressurization. PPSiOx underwent significant modifications as SiOx completely broke down. Neither thermal property was affected by pressure, as it was the processing temperature that induced tempering effects on the crystallization behaviour of polymeric components. Only PE/EVOH/ PE, when in contact with water as a simulant, presented a decrease in the melting point temperature. Copyright © 2008 John Wiley & Sons, Ltd. Received 7 November 2007; Revised 19 November 2007; Accepted 7 December 2007 KEY WORDS HPP; packaging materials; mechanical behaviour; scanning electron microscopy (SEM); thermal behaviour; DSC * Correspondence to: M. J. Galotto, LABEN-CHILE, Laboratorio de Envases, Dpto de Ciencia y Tecnología de Alimentos, Facultad Tecnológica, Edificio Alimentos, USACH, Obispo Umaña 050, Santiago, Chile. Laboratorio de Envases. Facultad Tecnológica. USACH. Email: mgalotto@lauca.usach.cl Copyright © 2008 John Wiley & Sons, Ltd. INTRODUCTION In the last decade, non-thermal inactivation tech- niques have been a major issue of research, driven by an increase in consumer demand for nutritious, fresh-like food products with a high organoleptical quality and an acceptable shelf life. Among the non-thermal techniques (pulsed electric fields, magnetism, irradiation, electron beam, ultrasound, ultraviolet light or ozone treatments), high hydro- static pressure has received the most attention in food processing. When applying high-pressure processing (HPP) as a food preservation process (from 300 to 800 MPa), micro-organisms are inac- tivated without the use of heat and therefore vitamin content, food flavour and colour are not