Convenient detection of white pepper adulteration by portable NIRS and spectral imaging with chemometrics

• A portable raster NIRS for grade recognition of adulterated white pepper was developed. • Adulteration data acquisition in seconds manifested the high time-efficiency and portability. • Visual quantification of adulterant in white pepper was realized by hyperspectral imaging. As an important condiment, the quality of pepper attracts much attentions. Due to the high illegitimate interests, pepper adulteration has become more and more serious. Non-destructive and low-cost adulteration detection is urgently needed in on-site scenario. As required, a portable NIR spectrometer was attempted to establish the grade recognition models by LDA, SVM, PLS-DA and SIMCA. Subsequently, quantitative modeling was carried out on piperine, and the optimal model obtained the R 2 c of 0.979, R 2 p of 0.973, and RPD of 6.05, which achieved an excellent quantitative performance. Moreover, to further visualize the adulteration, samples with different adulterant concentrations were scanned by hyperspectral imaging. The MCR-ALS was used to reduce the dimensionality of multivariate data and execute iterative calculation. Finally, the pixel concentrations in the spectral image were reconstructed to obtain the visual distribution of adulterant. Overall results demonstrate that a complete non-destructive detecting solution was provided for the analysis of adulteration of white pepper.