Effect of high-pressure processing on the mechanical and barrier properties of selected packagings

Abstract

This investigation focuses on the effect of high-pressure processing (HPP) on possible changes of the mechanical properties and of the water vapour permeability of seven selected packaging materials. NOD 259 (PA-PE), BB4L (Cryovac-Grace packaging), PET/BOA/PE, PET/PVDC/PE, PA/SY, LDPE and EVA/PE were investigated (PET, polyester; PE, polyethylene; SY, surlyn; LDPE, low-density polyethylene; EVA, polyethylene–vinyl acetate co-polymer; BOA, biaxially oriented polyamide). These packaging materials were selected because of their interest to the food industry. All had an internal film of PE for food use. High-pressure tests were realized at 10°C for 10 min at pressures of 200, 400 and 600 MPa, with water as a food-simulating fluid. The depressurization rate was either rapid (pressure drop in <10s) or slow (20 MPa/min). Permeability to water vapour was realized using the NFF H 00 030–ASTM E96-90 standard. Mechanical tests were carried out with a tensile testing machine (Lloyd LR5K), according to the NF 54-102 standard. Maximal stress, rupture stress and strain at rupture were evaluated with non-treated and treated samples. Obtained results showed that HPP minimally affects the mechanical strength of packaging material. The depressurization rate did not have any significant influence in our conditions. The barrier properties to water vapour were not significantly affected and were even slightly enhanced for LDPE, which is a packaging material commonly used for HPP applications and at least as a food contact material. Copyright © 2006 John Wiley & Sons, Ltd.