## 3 Results and Discussion
### Principal Component Analysis for Polyphenic Extracts of Z. officinal Rhizes  
A statistical Principal Component Analysis (PCA) was performed for the _Z. officinal_ rhizomes (\(n=12\)) harvested at term, considering all nine variables, specifically TG, all five individual gingerols and shogaol contents, FC and DPPH values. Two components, namely PC1 and PC2, were obtained (loadings > 0.44). The first component (PC1) represented 52.11% of total variance and showed a negative correlation with TG, 6-gingerol and FC and was positively correlated with DPPH. The second component (PC2) described 23.13% of the total variance and was positively correlated to 6-gingerdiol and 6-shogaol.  
As illustrated in the graphical representation of the two components (Figure 14), _Z. officinal_ samples are distributed along PC1, showing variability for the above-mentioned gingerol contents, reducing capacity and antioxidant activity. Some samples have particularly high values in PC1, for instance WR-1 and WR-2, which means poorer TG and 6-gingerol contents, as well as low FC and DPPH antioxidant activities. The graph shows samples from the Northern and Northwestern regions with similar PC1 values, except for samples NR-3 and NR-4, due to their higher TG, 6-gingerol, FC and DPPH values in respect to the other samples from those regions. The lowest PC1 value pertains to rhizomes SR-1, which agrees with this sample exhibiting the highest TG, 6-gingerol contents, FC and DPPH antioxidant activity.  
Samples are also distributed along PC2, showing variability in 6-gingerdiol and 6-shogaol contents for the 12 rhizomes. All samples from the Northern region present low PC2, therefore low 6-shogaol and 6-gingerdiol contents. On the other hand, samples from the Northwestern region, present the highest variability in PC2. The highest PC2 values are presented by samples NW-1, NW-2 and SR-1, indicating higher content of the above-mentioned compounds.  
Finally, our findings show that although differences were observed in the composition ranges between products from different regions, sample SR-1 stands out significatively, showing the highest PC1 and PC2 values due to its rich content of gingerols and shogaol previously mentioned and the highest FC reducing capacity and DPPH antioxidant activity.  
Overall, findings for _Z. officinal_ rhizomes clearly indicate polyphenic composition analogous to previously reported results [12; 25] and higher gingerols content in all Costa Rican samples with respect to the literature [26; 28; 29]. These results and the antioxidant activity values obtained for these extracts suggest their potential benefits in respect to other biological activities [50; 51] and towards their application in the dietary supplementsin industry. Further, PCA indicating location influence as well as results from the controlled experimental studies at variable harvest times and growth conditions, suggests the importance of future studies regarding environment, soil and other cultivation conditions to assess their influence in singerols and shogaols contents for these Costa Rican rhizomes, as well as further in vitro and in vivo research on other biological activities.