Table 2: Calibration and validation results for determination of luwak content in luwak-arabica blend using original and preprocessing spectra in the range 200–450 nm.

Type of spectraRMSECRMSECVBias

Original70.970.0290.062−0.0032.92
Moving average smoothing with 5 segments70.970.0290.042−0.0024.31
Savitzky-Golay smoothing with window width of 13 points and polynomial order 270.980.0280.039−0.0024.64
Median filter smoothing with 3 segments70.980.0270.050−0.0033.62
MSC70.980.0260.055−0.0013.29
SNV70.980.0250.054−0.0013.35
Baseline offset70.980.0270.060−0.0023.02
Mean centering70.970.0290.062−0.0032.92