Table 2.

Statistical parameters of the built models with and without data preprocessing (PLS-DA).

Label	Preprocessing	Number of latent variable	Calibration		Cross validation
			R-square (%)	RMSEC	R-square (%)	RMSECV
OO1	Without preprocessing	3 LV	91	0.14	89	0.16
OO2			94	0.12	93	0.13
OO3			89	0.16	89	0.17
OO1	Smoothing (Savitzky and Golay)	3 LV	90	0.15	89	0.16
OO2			94	0.12	94	0.12
OO3			89	0.16	87	0.17
OO1	Detrend (polynomial 1)	3 LV	91	0.15	86	0.18
OO2			95	0.11	90	0.15
OO3			89	0.16	87	0.17