The detection of organic polymers as contaminants in foodstuffs by means of the fluorescence decay of their auto fluorescence

Products such as food can become contaminated during their manufacture or afterwards. Depending on the type of substance causing the contamination, these contaminants can be harmful to health and difficult to detect by visible inspection. The suitability of fluorescence decay and FD-FLIM for the detection of plastics contamination in foodstuffs is demonstrated. Therefore, a procedure for the detection of contaminating organic polymers (plastics) in processed meat such as salami by means of the fluorescence decay time of auto fluorescence is described. The auto fluorescence of processed meat was found to decay according to first order with a typical time constant of about 2 ns, whereas the time constant of significant polymers for the processing of meat is generally appreciably higher (2.5 ns – 5.5 ns depending on the polymer). As a consequence, contaminating organic polymers can not only be globally detected by means of the fluorescence decay but also localised in two-dimensional imaging. The present study reports a high potential of FD-FLIM for rapidly identifying and differentiating different plastics on and in different foodstuffs. The method allows an improved quality control of foodstuffs. • Proof-of-principle for FD-FLIM used to detect plastics in processed meat. • Determination of the fluorescence lifetime of processed meat, PA, PVC, PET, and HDPE. • Classification of investigated materials in a single fluorescence lifetime image. • Rapid localisation in two-dimensional fluorescence lifetime imaging.