A variety of flexible, high barrier packaging material may be used to contain samples of high-pressure processing. The volume, geometry, and composition (polymer type, film thickness, sealing properties and barrier properties) of the packaging material are important considerations for selection as packaging material in high pressure processing. At least one interface of the package should be flexible enough to transmit pressure. Thus, rigid metal containers may not survive the pressure treatment. Presence of headspace air, oxygen in particular can adversely affect product quality at elevated pressure-temperature conditions. Dissolved oxygen becomes more reactive (ground oxygen) when pressure is applied. Furthermore, air has different compressibility than water and more effort needs to be made to compress the air. Thus, it would be desirable to minimize the presence of headspace air in the packages or preferably vacuum package the product. It is worth to note that intensity of pressure-thermal treatment can alter the barrier properties of packaging material.