Identifying and selecting edible luminescent probes as sensors of food quality

Foods contain a plethora of aromatic molecules-natural colors, synthetic dyes, flavors, vitamins, antioxidants, etc.-that are luminescent, exhibiting prompt fluorescence or delayed phosphorescence. Although food autofluorescence has been used to detect specific contaminants (e.g., aflatoxins) or to authenticate specific foods (olive oil), much of the potential of using the optical luminescence of intrinsic molecules for sensing properties of foods is unrealized. We summarize here work characterizing the photophysical properties of some edible, and potentially GRAS (generally-recognized-as-safe), chromophores and especially their sensitivity to, and thus potential for sensing, various physical-viscosity, mobility/rigidity-or chemical-polarity, pH-properties of food known to reflect or be indicative of food quality, stability, and safety. A thoroughgoing characterization of and robust protocols for interpretation of the luminescent signals from edible chromophores can expand the repertoire of analytical techniques available to monitor quality, and even safety, of the food supply at various stages of production, distribution and storage or even at point of sale.