Odor Characterization of Post-Consumer PP Bottles after Different Washing Processes

One of the reasons impeding recyclates to be inserted into a circular economy is their unpleasant odor. To achieve a better understanding of this problem and potential solutions, the present study aimed to assess how different washing processes can affect the odor composition of post-consumer PP bottles. Three different washing procedures, encompassing the use of detergent and caustic soda, and different temperatures, were used. The odor profiles of the unwashed and washed samples were determined by descriptive sensory analysis. Further, odoractive compounds in the PP samples were evaluated by gas chromatography-olfactometry and ranked according to their potential odor contribution via odor extract dilution analysis. The most dominant smell attributes in all samples were moldy, flowery, and soapy, mainly originating from compounds used in cosmetics, fragrances, and cleaning products.