Rapid identification of artificial and natural food colorants with surface enhanced Raman spectroscopy

A rapid method has been developed for detecting food colorants based on surface-enhanced Raman spectroscopy (SERS). The technique was demonstrated to have the ability to identify a wide variety of artificial and natural food coloring agents currently approved or banned in the United States. A simple silver nanoparticle substrate was used to enhance the signal, requiring less than 10 min of sample preparation prior to analysis. All of the colorants had distinct SERS signals and could be easily differentiated based on their spectral features and using principal component analysis. Further tests confirmed that SERS is capable of quantifying adulteration with chemically and visually similar colorants, and can detect signals from some artificial colorants down to at least 1 ppm concentrations. Additionally, both artificial and natural colorants could be identified in commercially available food products using the technique. This study establishes a database of 16 commonly used artificial and natural food colorants. The simplicity of the SERS method and its strong effectiveness for detecting colorants indicate that it has great potential to be used for practical applications in this area.