Fluorimetric detection of protoporphyrins as an indicator for quality monitoring of fresh intact pork meat

In fresh meat production fast and non-destructive quality monitoring along the distribution chain is a key aspect to guaranteeing high quality and safe products for consumption. The applicability of fluorescence spectroscopy using protoporphyrins as indicators for meat ageing was investigated. Porcine musculus longissimus dorsi (MLD) was stored in slices over 20 days at 5 and 12 °C and measured every day with an excitation of 420 nm and an emission range of 550–750 nm. Additionally, pH, drip loss and colour were examined to assess possible correlations.The obtained spectra of the MLD showed an increase in three peaks at 592, 638 and 705 nm which could be reconstructed using the spectra of standard solutions of protoporphyrin IX (PP) and zinc protoporphyrin IX (ZnPP) or magnesium protoporphyrin (MgPP), respectively.Using principal component analysis (PCA) on the fluorescence spectral data, the meat slices stored at 5 °C showed differences in the fluorescence signal after the 10th day and 5th day when stored at 12 °C. An interrelationship between the additional analyses and the fluorescence intensities on these relevant days could not be established.In conclusion, the increase of ZnPP fluorescence due to temperature related changes of physiological meat properties is capable of serving as a quality indicator with regards to inadequate conditioning (e.g. during transportation and/or storage) of pork meat.