Abstract: To accurately, safely, and efficiently evaluate the bitterness of Traditional Chinese Medicines
(TCMs), a robust predictor was developed using robust partial least squares (RPLS) regression method
based on data obtained from an electronic tongue (e-tongue) system. The data quality was verified by
the Grubb’s test. Moreover, potential outliers were detected based on both the standardized residual
and score distance calculated for each sample. The performance of RPLS on the dataset before and
after outlier detection was compared to other state-of-the-art methods including multivariate linear
regression, least squares support vector machine, and the plain partial least squares regression. Both
R2 and root-mean-squares error (RMSE) of cross-validation (CV) were recorded for each model. With
four latent variables, a robust RMSECV value of 0.3916 with bitterness values ranging from 0.63 to
4.78 were obtained for the RPLS model that was constructed based on the dataset including outliers.
Meanwhile, the RMSECV, which was calculated using the models constructed by other methods,
was larger than that of the RPLS model. After six outliers were excluded, the performance of all
benchmark methods markedly improved, but the difference between the RPLS model constructed