High-sensitivity hyperspectral coupled self-assembled nanoporphyrin sensor for monitoring black tea fermentation

The rapid and scientific method for monitoring the quality of black tea fermentation is of great significance to the quality control of black tea production. This study proposed a novel method for evaluating the fermentation quality of black tea by using hyperspectral imaging technology with self-assembled nanoporphyrin (N-TPP) dyes, which were used as aroma capture probes in the black tea fermentation process. Scanning electron microscopy and ultraviolet-visible spectroscopy were performed to characterize the N-TPP. Then, the results of the colorimetric sensor array (conventional camera color method) and the proposed hyperspectral methods were compared. Finally, the hyperspectral information of N-TPP with higher sensitivity was collected, and the qualitative models of evaluating black tea fermentation quality were established using support vector machine (SVM), extreme learning machine, and linear discriminant analysis. Among these models, the SVM model exhibited the highest discriminant accuracy. The accuracy of the SVM model based on the hyperspectral information of the self-assembled N-TPP array was 98.85 %, which was considerably higher than that (68.97 %) of the SVM model based on the color information of the porphyrin array. The results revealed that the proposed method can effectively improve the monitoring accuracy of black tea fermentation quality.