Simultaneous detection of mixed colorants adulterated in black tea based on various morphological SERS sensors

Colorant adulteration is a common problem in tea safety control; thus, a rapid identification method is required. In this study, we optimized the fabrication parameters of various sensors to enhance their performance. R6G was used as a probe molecule, demonstrating that the sensnor remained stable for 120 days. Based on surface-enhanced Raman spectroscopy, the optimized sensors were used to identify and quantify mixed colorants (sunset yellow, lemon yellow, carmine, and erythrosine). Partial least squares prediction models were developed for each colorant (0.5-300 μg/mL), with R² > 0.900 and RPD > 2.27; these indicated the accuracy of the sensors. The results also revealed a model recovery range of 95.9 % to 116 %, with RSD < 3.94 %, indicating the universality of our proposed method. Overall, the proposed method enables the detection of mixed-colorant adulteration in black tea within 3 min, thereby representing a novel method for the assessment of tea quality.