Improved Design of Ethylene-Vinyl Alcohol and Polypropylene-Based Packaging for Microwave-Assisted Thermal Sterilization and Pasteurization

Primary Author: Saleh Al-Ghamdi

Faculty Sponsor: Shyam Sablani


Primary College/Unit: Agricultural, Human and Natural Resource Sciences

Category: Engineering and Environmental Science

Campus: Pullman





Principal Topic

Oceans are full of plastic waste and plastic packaging production and transportation have an environmental burden of greenhouse emissions. To reduce this pollution and the plastic production footprint. The aim of this study was to design a reduced thickness of ethylene vinyl alcohol (EVOH) and polypropylene (PP)-based trays for microwave-assisted thermal processing.


We designed multilayered packaging with high barrier performance resulting in symmetrical and asymmetrical layers’ structures that were subjected to conventional and microwave-assisted thermal food sterilization and pasteurization processes. Positron annihilation lifetime spectroscopy (PALS) or structural, mechanical, and barrier properties were measured before and after thermal processing and during the shelf life. Oxygen ingress into the package was monitored utilizing nondestructive fluorescence sensors. Model food was used as a color-changing indicator sensitive to O2.


Results showed that PALS did not reveal any apparent increase in free volume after sterilization process. Mechanical properties showed better performance for the new reduced thickness design.  Barrier properties changed after microwave-assisted thermal sterilization. Oxygen ingress during shelf life was negligible for pasteurized trays. However, conventional sterilization showed higher O2 ingress than microwave-assisted sterilization. Model food showed great potential and the feasibility of reducing the package thickness without food quality deterioration. We have obtained better or comparable packaging performance with a 24% overall reduction in package thickness. These findings showed the possibility of reducing package thickness resulting in a reduction of the overall used material that can translate to less carbon footprint and better financial and environmental choices.