Odor Modification in Rigid Polyethylene Waste: Impact of Different Washing on Sensory Analysis and Characterization

Persistent odor in recycled polyethylene (PE) limits its use in high-demand applications, necessitating effective deodorization. We investigated how washing affects the odor profile and intensity of post-consumer rigid PE, using sensory analysis, comparative odor extract dilution analysis (cOEDA), and two-dimensional gas chromatography-mass spectrometry/olfactometry (2D-GC-MS/O). Three methods were evaluated, varying in temperature and surfactant use: room temperature water (RT, 25°C), hot water (HW, 80°C), and detergent with caustic soda (DW). Sensory analysis showed that no treatment significantly reduced overall odor intensity or hedonic ratings, although washing modified the qualitative odor profile. Median values indicated a modest downward trend for DW (17% reduction), though not statistically significant. cOEDA and 2D-GC-MS/O results aligned with these qualitative shifts, including reduced moldy and increased soapy and flowery notes. Of 32 odor-active compounds detected in post-consumer rigid PE, 28 were identified. Rose oxide, dihydromyrcenol, hexyl salicylate, and α-hexylcinnamaldehyde are reported for the first time in post-consumer PE. This study deepens understanding of post-consumer PE odor and highlights challenges in developing advanced deodorization techniques for the circular economy.