A near-infrared fluorescence assay method to detect patulin in food.

Patulin (PAT) is a toxic secondary metabolite (mycotoxin) of different fungal species belonging to the genera Penicillium, Aspergillus, and Byssochlamys. They can grow on a large variety of food, including fruits, grains, and cheese. The amount of PAT in apple derivative products is a crucial issue because it is the measure of the quality of both the used raw products and the performed production process. Actually, all current methodologies used for the quantification of PAT are time-consuming and require skilled personnel beyond the sample pretreatment methods (e.g., high-performance liquid chromatography, mass spectrometry, and electrophoresis techniques). In this work, we present a novel fluorescence polarization approach based on the use of emergent near-infrared (NIR) fluorescence probes. The use of these fluorophores coupled to anti-PAT antibodies makes possible the detection of PAT directly in apple juice without any sample pretreatment. This methodology is based on the increase of fluorescence polarization emission of a fluorescence-labeled PAT derivative on binding to specific antibodies. A competition between PAT and the fluorescence-labeled PAT derivative allowed detecting PAT. The limit of detection of the method is 0.06 μg/L, a value that is lower than maximum residue limit of PAT fixed at 50 μg/L from European Union regulation.