## 3 Results and Discussion
### Huanglongbing Effects on the Volatile Profile of 'Ray Ruby' Grapefruit juice
** & **VOC** & **Calculated** & **Reference** & \multicolumn{3}{c}{**2020**} & \multicolumn{3}{c}{**2021**} \\ \cline{4-11}  & **RI\({}^{\circ}\)** & **RI\({}^{\circ}\)** & **RI\({}^{\circ}\)** & **HLB-** & **HLB-** & **\(\rho\)Value** & **Difference\({}^  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & \multicolumn{2}{c}{**Calculated**} & \multicolumn{2}{c}{**Reference**} & \multicolumn{2}{c}{**2020**} & \multicolumn{2}{c}{**2021**} \\ \hline
**Peak No. ** & **VOC** & **RI\({}^{*}\)** & **RI\({}^{*}\)** & **HLB-** & **HLB-** & **P-Value** & **Difference\({}^{*}\)** & **HLB-** & **HLB-** & **_P-Value** & **Difference** \\ \hline
43 & o-Cymont-5d &  
\begin{table}
\begin{tabular}{l l c c c c c c c c c} \hline
**Peak No. ** & **VOC** & **Calculated** & **Reference** & \multicolumn{3}{c}{**2020**} & \multicolumn{3}{c}{**2021**} \\ \cline{3-10}  & **RI \({}^{\circ}\)** & **RI \({}^{\circ}\)** & **RI \({}^{\circ}\)** & **HLB-** & **HLB-b** & \(P\)Value & **Difference \({}^{\circ}\)** & **HLB-** & **HLB-b** & **_P-Value_** & **Difference** \\ \hline \multicolumn{1}{c}{**Chemical class**} & & & & & & & & & & \\ \hline \multicolumn{10}{c}{**M**ocetreprep hydrocarbons**} \\ \multicolumn{10}{c}{**S**opoluminescence hydrodynamics**} \\ \multicolumn{10}{c}{**S**opoluminescence hydrodynamics**} \\ \multicolumn{10}{c}{**S**opoluminescence hydrodynamics**} \\ \multicolumn{10}{c}{**S**opoluminescence hydrodynamics**} \\Figure 5: Combined cluster analysis and heat map of investigated grapefruit juice samples of healthy (HLB\(-\)) and HLB-affected fruits (HLB+) from 2020 (HLB\(-\) 20 and HLB+ 20) and 2021 (HLB\(-\) 21 and HLB+ 21) harvests (columns) and identified VOCs (rows). Chemical groups increased and/or decreased by Huanglongbing (HLB) determined the average concentration of volatiles in juice extracted from ‘Ray Ruby’ grapefruit in two harvest seasons, 2020 and 2021. * Significant differences at \(p\leq 0.05\) according to [PERSON]’s HSD test in both years. HLB resulted in a significant reduction in aliphatic aldehydes and terpene ketones in the juice and an increase in aliphatic alcohols, aliphatic esters, and monoterpene hydrocarbons (Table 3, Figure 5). Long-chain aldehydes are known to contribute a lot to citrus juice aroma, with citrus-like, grassy, and soapy odors [33, 46, 47, 48]. In grapefruit, ketones  
Figure 6: Principal component analysis (PCA) score plot (**A**) and loading plot (**B**) of VOCs in the juice of ‘Ray Ruby’ grapefruit of healthy (HLB\(-\)) and HLB-affected (HLB\(+\)) fruits from 2020 (HLB\(-\) 20 \(\lx@paragraphsign\) and HLB\(+\) 20 \(\lx@paragraphsign\)) and 2021 (HLB\(-\) 21 \(\lx@paragraphsign\) and HLB\(+\) 21 \(\lx@paragraphsign\)) harvests. VOCs corresponding to the numbers are listed in Table 3.  
also strongly contribute to the flavor, mainly due to nootkatone, the main fragrant component of grapefruit [42; 48]. On the other hand, ethanol is the aliphatic alcohol derived from the fermentation process, which is responsible for a fermented flavor in fresh fruit and juice [12; 46]. The decrease of C8-C10 aldehydes and increased ethanol and esters could result in an \"off-flavor\" in the juice [46]. Valencene is considered the precursor of nootkatone, and the levels of both compounds have been reported to increase as the fruit matures [42; 49]. The fact HLB decreased nootkatone in the peel oil and juice confirmed that HLB slowed the maturation of fruits, similar to immature orange fruits [9]. In Valencia oranges, valencene accumulates throughout fruit maturation, but in grapefruit, it is further oxidized to nootkatone [50]. On the other hand, we did not identify the presence of valencene in the peel oil (Table 2). Consistent with our findings, previous studies also found that \(\beta\)-myrcene, D-limonene, and total terpen had higher concentrations in HLB symptomatic Hamlin juice than healthy ones [8; 9]. Previous studies also showed decreased levels of aldehyde compounds in Hamlin orange juice of HLB symptomatic fruits compared with the juice of healthy fruits [8; 48].