# Profiles of Volatile and Phenolic Compounds as Markers of Ripening Stage in Candonga Strawberries
## 3 Results and Discussion
### Phenolic Compounds in Half-Red and Red Strawberries
The chromatogram at 360 nm was dominated by quercetin-3-\(O\)-glucuron (P7), which was more abundant in Half-red-H1 and Half-red-H2 than in the ripened counterpart. Strawberries have been generally described as fruits rich in EA; however, the content of free EA can vary in a wide range, depending on the cultivar as well as on a series of abiotic factors [26]. In the current strawberry samples, free EA was detected at concentrations lower than the limit of quantification, co-eluting with kaempferol-3-\(O\)-glucose (peak 6, P6), as also confirmed with a separate injection of pure EA. MS and MS/MS analysis allowed to establish the presence of free EA and assess that it was slightly more intense in half-red than in ripe strawberry [25] (data not shown). No glycosylated derivatives of EA were detected among the main compounds by RP-HPLC, while EA conjugates (i.e., pentoside and hexoside) were detected both in half-red and red strawberry by ion extraction in the MS runs (data not shown). Several minor signals of relatively high molecular weight compounds detected by LC-MS were likely ellagitannins that could be converted into EA by processing or chemical hydrolysis [25]. A detailed characterization of strawberry ellagitannins is challenging and requires dedicated investigations [24; 27]. The semi-quantitative figures determined for the individual phenolic compounds were in line with most of the previous determinations reported by other authors [8]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \multirow{2}{*}{**Polyphenols**} & \multirow{2}{*}{**Code**} & \multicolumn{4}{c}{**H1**} & \multicolumn{4}{c}{**H2**} & \multicolumn{4}{c}{**H3**} \\ \cline{2-13}  & & **Half-Red** & **Red** & \(p\) & **Half-Red** & **Red** & \(p\) & **Half-Red** & **Red** & \(p\) \\ \hline \(p\)-couamyl hexoside & P1 & 9.6 & b & 28.5 & a & **** & 11.4 & b & 25.9 & a & **** & 12.7 & b & 29.0 & a & **** \\ cyanidin-3-\(O\)-glucose & P2 & 1.8 & b & 3.3 & a & **** & 2.0 & b & 3.8 & a & **** & 1.5 & b & 3.1 & a & **** \\ pelargonidin 3-\(O\)-glucose & P3 & 25.1 & b & 48.7 & a & **** & 19.8 & b & 42.6 & a & **** & 22.4 & b & 43.6 & a & **** \\ pelargonidin 3-\(O\)-rutinoside & P4 & 3.1 & b & 5.6 & a & **** & 2.4 & b & 4.5 & a & **** & 3.5 & b & 5.1 & a & **** \\ quercetin-3-\(O\)-glucose & P5 & 5.1 & a & 4.2 & b & **** & 4.1 & a & 3.6 & b & * & 3.3 & a & 3.2 & b & * \\ kaempferol-3-\(O\)-glucose & P6 & 2.1 & b & 2.3 & a & * & 2.5 & a & 2.1 & b & *** & 2.1 & b & 2.3 & a & * \\ quercetin-3-\(O\)-glucuron & P7 & 20.2 & a & 17.0 & b & **** & 18.6 & a & 15.8 & b & **** & 12.5 & b & 14.1 & a & **** \\ kaempferol-3-\(O\)-glucuron & P8 & 2.9 & b & 3.1 & a & ** & 3.0 & b & 3.4 & a & ** & 2.5 & b & 2.8 & a & ** \\ \hline \end{tabular} For each parameter the mean values followed by different letters (a, b) are significantly different (\(p\leq 0.05\)) according to least significant difference (_1 SD_) test. Significance: ns = not significant; **** & & & & & & & & & & & & & & & & \\ \({}^{*}\) significant for \(p\leq 0.05\).  
\end{table} 
Table 2: Assignment and semi-quantitative determination of phenolic compounds measured in strawberries cv “Sabrosa” at two different ripening stages (half-red or red) and at three harvest times (H1, H2, H3).