## 3 Results  
### Spectral Information  
The raw spectra data from calibration and validation sample sets of unopened pre-sliced MAP packages of Iberian _chorizo_ manufactured from raw material belonging to three commercial categories according to the current IQS [6] are shown in Figure 2.  
The NIR spectra data revealed similar shapes regardless of the official commercial category of raw material, showing the same peaks and valleys along the entire scanned region (1000-2500 nm) in both calibration (Figure 2A) and validation (Figure 2B) sample sets. Nevertheless, there were reflectance intensity differences due to commercial categories of raw material. Lower reflectance was observed by spectra from Iberian _Chorizo_ from _Black_ and _Red_ categories, which overlapped along 1000-2500 nm compared to _chorizo_ spectra from _White_ category, which yielded higher reflectance intensity. On the other hand, from the value 1900 nm onwards it can be observed the signal reached by the detector was very low and in the spectra range between 2300 and 2500 high spectral noise was observed. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multirow{2}{*}{**Commercial Category**} & \multirow{2}{*}{**Pre-Treatment**} & \multirow{2}{*}{**Range**} & \multicolumn{4}{c}{**Calibration**} & \multicolumn{4}{c}{**External Validation**} \\ \cline{5-10}  & & & **n** & **SE** & **SP** & **n** & **SE** & **SP** \\ \hline _Black_ & SG 1,4,4,1 & 1000–2300 & 72 & 90.48 & 86.27 & 31 & 81.82 & 60.00 \\ _Red_ & SG 1,4,4,1 & SUV-DE & 1000–1800 & 72 & 84.00 & 97.87 & 31 & 90.00 & 80.95 \\ _White_ & Absorbance & 1000–1800 & 72 & 88.46 & 93.48 & 31 & 80.00 & 95.24 \\ \hline _Black, Red_ and _White_ = commercial categories of raw material used for manufacturing Iberian _chorizo_; SG = Savitzky-Golay derivates; SNV = Standard normal variate; DE = de-trending; n = number of samples; SE = sensitivity (%); SP = specificity (%). & & & & \\ \hline \end{tabular}
\end{table} 
Table 4: LDA results of the best fitting equation for pre-sliced MAP Iberian _chorizo_ classification within the official commercial categories of the raw material (_Black, Red_ and _White_). \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \multirow{2}{*}{**Commercial Category**} & \multirow{2}{*}{**Pre-Treatment**} & \multirow{2}{*}{**Range**} & \multirow{2}{*}{**PCs**} & \multicolumn{4}{c}{**Calibration**} & \multicolumn{4}{c}{**External Validation**} \\ \cline{5-10}  & & & & **n** & **SE** & **SP** & **n** & **SE** & **SP** \\ \hline _Black_ & Absorbance & 1000–2300 & 1 & 21 & 100.00 & 21.57 & 31 & 90.91 & 45.00 \\ _Red_ & SG 1,4,4,1 & 1000–1800 & 9 & 25 & 100.00 & 46.81 & 31 & 90.00 & 47.62 \\ _White_ & SNV-DE & 1000–1800 & 1 & 26 & 100.00 & 63.04 & 31 & 90.00 & 47.62 \\ \hline _Black, Red_ and _White_ = commercial categories of raw used for manufacturing Iberian _chorizo_; SG = Savitzky-Golay derivates; SNV = Standard normal variate; DE = de-trending; PCs = number of principal components; n = number of samples; SE = sensitivity (%); SP = specificity (%). & & & & \\ \hline \end{tabular}
\end{table} 
Table 3: SIMCA results of the best fitting equation for pre-sliced MAP Iberian _chorizo_ classification within the official commercial categories of the raw material (_Black, Red_ and _White_). Additionally, the regression coefficients of wavelengths of Iberian _Clorizo_ from PLS-DA after SNV-DE (1000-2300 nm) for _Black_ (Figure S2A) and SG 1,\(A\),1 SNV-DE (1000-2300 nm) for _Red_ and _White_ (Figure S2B,C, respectively) were graphically presented in the supplementary material. It is important to note that for the _black_ label, the wavelengths around 1100 nm and between 1200 nm and 1600 nm were the ones that stood out for their high weight (regression coefficients) (Figure S2A). Similarly, the wavelengths mainly comprised between 1000 nm and 1400 nm for _Red_ (Figure S2B) and 1000 nm and 1500 nm for _White_ (Figure S2C) category were the wavelengths that had the greatest weight.