## 3 Results and Discussion
### Evaluation of Z. officinal Roscoe rhizomes from Experimental Plots
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Product** & **Cultivar** &
\begin{tabular}{c} **Harvest** \\ **(weeks)** \\ \end{tabular} & **Growth Environment** \\ \hline NR-5 & GC & 40 & Open-field \\ NR-6 & GC & 20 & Open-field \\ NR-7 & GC & 40 & High tunnel \\ NR-8 & GC & 20 & High tunnel \\ NR-9 & HW & 40 & High tunnel \\ NR-10 & HW & 20 & High tunnel \\ \hline \hline \end{tabular}  
* Cultivars: Grand Cayman (GC), Hawaiian (HW).  
\end{table} 
Table 5: Characteristics of _Z. officinal_ Roscoe rhizomes from experimental plots. content, followed by samples NR-9 (56.91 mg/g dry sample) and NR-8 (54.67 mg/g dry sample). The lowest TG content was presented by sample NR-5 (30.44 mg/g dry sample). Two-way ANOVA was performed to evaluate the effect of the cultivar, harvesting maturity and growth condition on the TG and 6-shogaol contents. For TG content, the results showed a significant difference (\(p<0.05\)) in all three parameters, with higher gingerol content obtained with HW cultivar, grown under HT environment and harvested at 20 weeks. On the other hand, results for 6-shogaol content showed a significant difference (\(p<0.05\)) only for the cultivar, where the HW cultivar presented the higher shogaol content, with levels not aligning with USP requirements (6-shogaol content \(\leq 0.18\)%) [20]. In turn, obtaining better results by harvesting at 20 weeks is in agreement with previous reports attributing a higher percentage content of these metabolites in ginger oleoresin at 6 months in respect to 9 months harvesting, due to the fast increase of rhizome weight and fiber development approaching maturity [47]. For these samples, the Folin-Ciocalteu reducing capacity and DPPH antioxidant activity assays were also applied and the results are summarized in Table 7.  
Results for FC-reducing capacity range from 64.20 up to 202 mg GAE/g extract. One-way ANOVA followed by Tukey post hoc test indicated significant difference (\(p<0.05\)) between all samples. Samples NR-5 and NR-6, both grown in OF, showed the lowest reducing capacity, consistent with results obtained in the TG content analysis. Samples NR-9 and NR-10 corresponding to Hawaiian cultivar showed the highest values, with an average FC of 190.33 mg GAE/g compared to results for NR-7 and NR-8 corresponding to GC cultivar grown under the same conditions, which hold an average of 149.43 mg GAE/g, hence 21% lower. Results for the DPPH antioxidant activity evaluation show the same trend observed for the determination of FC reducing capacity and UPLC TG contents with samples NR-9 and NR-10 showing the lowest values, 18.15 and 15.56 \(\upmu\)g/mL respectively, and therefore a better antioxidant activity. On the other hand, sample NR-5 presented the lowest antioxidant activity, with an IC50 of 46.84 \(\upmu\)g/mL. Two-way ANOVA tests were performed to evaluate the effect of the cultivar, growth condition and harvesting weeks on the FC reducing capacity and DPPH antioxidant activity. Results showed a significant difference (\(p<0.05\)) for all three parameters, with higher reducing capacity and better antioxidant activity obtained for HW cultivar, grown under HT and harvested at 20 weeks. Comparison of these results with the prevalent conditions for _Z. officinal_ cultivation in Costa Rica show the impact on variability that these factors entail. For instance, high-tunnel (HT) practices are known to protect crops, reducing pest related affectation and extending the growing season, influencing the nutritional content [48], which could be associated with the present results observed for ginger rhizomes under HT conditions. In turn, the Hawaiian variety, originally from Philippines [49] and introduced more recently in the country, could seem more promising due to the higher TG content.