During PLS regression, four different spectral pretreatments were applied to set out the typical absorption peaks of the spectra. The results of PLS and the applied pre-treatment are summarized in Table 2 for each constituent. Concerning the NIR analyses and the mathematical evaluation of the spectra, the optimal equations were found by applying the first derivative + MSC and second derivative mathematical pre-processing in all analyses similarly to Pedro and Ferreira (2007).