Designing thinner wall ethylene-vinyl alcohol copolymer and polypropylene-based semi-rigid trays for microwave-assisted thermal sterilization and pasteurization processes

Abstract The goal of this research was to design a thinner wall tray for microwave-assisted thermal processing technologies. Three-layer (PP//EVOH//PP) sheets of different EVOH- and PP-layer thicknesses were coextruded. The sheets were then thermoformed into 8-oz trays with dimensions of 150 × 100 × 50 mm (L × W×D). Trays were filled with model foods and subjected to conventional and microwave-assisted pasteurization and sterilization processes. Barrier and mechanical properties were assessed before and after processing. Oxygen ingress, weight loss, and color kinetics were measured over a storage period of 3–6 months at 7, 23, and 37 °C. The newly-designed trays showed comparable or better performance in terms of O2 ingress and weight loss, with a 24 % reduction in wall thickness. Therefore, thinner EVOH and PP-based trays hold promise for use in microwave-assisted sterilization and pasteurization processes. This will result in a reduced carbon footprint and provide more economical alternatives to other forms of packaging that are currently available.