# From Vine to Wine: Non-Colored Flavonoids as Fingerprints
## 3 Results
### Multivariate Analysis
#### 3.3.2 Linear Discriminant Analysis  
Results of a linear discriminant analysis (LDA) performed to classify the Canary red wines analyzed according to grape cultivar, island of precedence, DO (Tenerife Island), and wine aging are presented in Table 5. Variable levels of correct classification were found before and after cross-validation. This table also shows the non-visible flavonoids influencing each of the discriminant functions that were selected from the stepwise analysis. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multicolumn{1}{c}{**Influencing Factors**} & \multicolumn{1}{c}{**Type of LDA**} & \
\begin{tabular}{c} **Correct Classification** \\ **(\% After Cross-Validation)** \\ \end{tabular} &
\begin{tabular}{c} **Selected Variables for** \\ **F1 and F2** \\ \end{tabular} \\ \hline
1. & Grape Cultivar & & \\ \hline  & All variables & 82.9\% & F1: M3 gl, Ider, Isor, Isgl \\  & & (68.8\%) & F2: TFlo, GFlo, Qder \\ \hline  & Stepwise & 62.4\% & F1: Myri, Isor, Q3 gl \\  & & (58.0\%) & F2: M3 gl, AFI, TFla, GFlo \\ \hline
2. & Precedence Island & & \\ \hline  & All variables & 84.9\% & F1: Myri, Q3 gu, AFlo \\  & & (73.7\%) & F2: L3 gl, Quer \\ \hline  & Stepwise & 73.2\% & F1: Myri, AFlo, Q3 gu \\  & & (72.7\%) & F2: M3 gl, Mder, GFlo \\ \hline
3. & Tenerife DO & & \\ \hline  & All variables & 65.8\% & F1: Myri, I3 gl, Ider \\  & & (49.3\%) & F2: Qder, TFlo, GFlo \\ \hline  & Stepwise & 47.3\% & F1: Epic, Myri, I3 gl \\  & & (45.2\%) & F2: Qder, Q3 gl, AFlo \\ \hline
4. & Wine Aging & \\ \hline  & All variables & 81.5\% & F1: Isor, Quer, Cate \\  & & (76.6\%) & F2: L3 gl, Ider, AFlo \\ \hline  & Stepwise & 75.4\% & F1: K3 gl, Isor, AFlo \\  & & (74.6\%) & F2: Myri, TFlo, Cate \\ \hline \hline \end{tabular}
\end{table} 
Table 5: LDA outcomes for classifying red wines based on the considered influencing factors. Using the full set of flavonoid variables, LDA achieved an 82.9% correct classification of red wines by grape cultivar, which dropped to 68.8% after cross-validation. When stepwise LDA was applied, the classification accuracy declined to 62.4% (58% after cross-validation), with M3 gl, Isor, Myri, and Q3 gl emerging as key variables for distinguishing grape cultivars. For instance, specifically for the Listan Negro samples, M3 gl and Q3 gl present relatively high mean concentrations compared to several other cultivars, whereas Isor and Myri show intermediate concentration levels. Such concentration patterns of these flavonoids collectively enable accurate differentiation and classification of Listan Negro samples. When classifying red wines by island of origin, LDA using all flavonoid variables yielded the highest correct classification rate of 84.9%, which decreased to 73.7% after cross-validation. In contrast, the stepwise LDA approach produced a lower accuracy of 73.2% (72.7% after cross-validation), with Myri, AFlo, and Q3 gu emerging as the most relevant variables for differentiating the red wines according to the production island. Red wines from La Gomera and Lanzarote islands achieved a 100% accuracy of correct classification, indicating no misclassification for these red wines. Red wines produced in Tenerife Island exhibited a high correct classification accuracy (91.1%), with minor misclassifications into La Gomera (2.7%), Gran Canaria (2.7%), El Hierro (2.1%), and La Palma (1.4%). Red wines from El Hierro and La Palma islands were moderately well classified in 72.2% and 73.3% of cases, respectively. In contrast, red wines produced in Gran Canaria Island had the lowest accuracy (30.8%), with significant misclassification in Tenerife (53.8%) and smaller proportions in La Gomera and El Hierro (both 7.7%). Wine aging yielded red wines which showed 81.5% of correct classification (76.6% after cross-validation) using all the variables. When stepwise LDA was applied, the correct classification lowered to 75.1% (74.6% after cross-validation). The relevant variables selected by the stepwise LDA for classifying red wines according to aging were K3 gl, Isor, AFlo, Myri, TFlo, and Cate.