Effects of Oxygen and Water Vapor Transmission Rates of Polymeric Pouches on Oxidative Changes of Microwave-Sterilized Mashed Potato

Polymer-based packaging with low oxygen (OTR) and water vapor transmission rates (WVTR) can be used to limit oxidative chemical changes in packaged foods, especially for the 3- to 5-year shelf life required for military rations and long-duration space foods. Microwave-assisted thermal sterilization (MATS) produces higher quality food with a potentially longer shelf life as a result of volumetric heating and the associated shorter process time. This study investigated the effects of the package-MATS process interactions and the resultant package barrier properties on food quality, using a mashed potato model food following MATS process of F0 = 9 min for 12 weeks at 50 °C. Two poly ethylene terephthalate (PET)-based (MFA, MFC) and one ethylene vinyl alcohol (EVOH)-based (MFB) retort pouches were tested, with OTRs of 0.20, 2.11, and 0.07 cc/m2·day and WVTRs of 2.64, 1.78, and 0.29 g/m2·day for MFA, MFB, and MFC, respectively; a foil double-sealed MFA pouch served as a control (MF0).