Towards SERS based applications in food analytics: Lipophilic sensor layers for the detection of Sudan III in food matrices

Highlights: • A lipophilic sensor layer was applied to enzymatically grown SERS substrates. • Sudan III molecules could be detected in presence of water-insoluble competitors. • The carcinogenic food dye Sudan III was detected in a relevant concentration range. • Multivariate statistics allows quantitative measurements of Sudan III. • Sudan III contaminations were successfully detected out of spiked paprika powder. - Abstract: Food safety is a topic of great importance for our society which places high demands on analytical methods. Surface enhanced Raman spectroscopy (SERS) meets the requirements for a rapid, sensitive and specific detection technique. The fact that metallic colloids, one of the most often used SERS substrates, are usually prepared in aqueous solution makes the detection of water-insoluble substances challenging. In this paper we present a SERS based approach for the detection of water-insoluble molecules by applying a hydrophobic surface modification onto the surface of enzymatic generated silver nanoparticles. By this approach the detection of the illegal water-insoluble food dyes, such as Sudan III in presence of riboflavin, as water-soluble competitor, is possible. Moreover, we demonstrate the usability of this kind of SERS substrates for determination of Sudan III out of spiked paprika extracts