Influence of Ultra-High Pressure Sterilization on the Structure of Polymer Films

The effect of ultra-high-pressure processing on the structure of polymer film pouches, commonly used in food packaging, has been studied. In particular, the effect of an air headspace on the polypropylene heat-sealing inner layer is reported. With increasing pressure, both nitrogen and oxygen gases become increasingly soluble in the polymer layer. If the pressure is rapidly released, this causes voids and pits to form in the inner layer. An estimate of the increased solubility (70-fold) is calculated from regular solution theory. Copyright © 2009 John Wiley & Sons, Ltd.