Effects of different storage conditions on quality related porphyrin fluorescence signatures of pork slices.

This study evaluated the potential of fluorescence as an indicator of pork quality by determining the effects of various conditions on fluorescence signatures (excitation at 420 nm, emission at 550-750 nm). Storage of porcine musculus longissimus dorsi in PE bags led to a clear increase in porphyrin fluorescence intensity after approx. 10 d post mortem. Modified gas atmosphere (70% O(2), 30% CO(2)) inhibited the fluorescence emission of zinc protoporphyrin and protoporphyrin IX due to quenching by oxygen. Bleaching processes caused similar effects by halogen light exposure during meat storage. However, already formed signals could not be manipulated by oxygen or halogen light. Storage under vacuum reduced the quenching effects and resulted in increased fluorescence intensities. Freezing and thawing of meat samples delayed and reduced the increase in fluorescence intensity. Only minor effects could be detected at long-term frozen storage for two months. Consequently porphyrin fluorescence analysis is a potential means to indicate changes of pork quality and remaining shelf life.