# 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 comprehensive pattern of polyphenols in the strawberry appears very complex, as compounds belonging to several classes, including hydroxycinnamic acid derivatives, flavonoids, and anthocyanins are variously represented. Despite numerous studies carried out to characterize strawberry metabolites, the current inventory of phenolic compounds emerging from the literature is controversial because of the large number of variety of cultivars available and the diversity of analytical methods employed. Nevertheless, the \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{10}{c}{**Harvest Time**} \\ \cline{2-13}  & \multicolumn{4}{c}{**H1**} & \multicolumn{4}{c}{**H2**} & \multicolumn{4}{c}{**H3**} \\ \cline{2-13}
**Parameters** & \multicolumn{4}{c}{**Ripening Stage**} \\ \cline{2-13}  & **Red** & **Half-Red** & \(p\) & **Red** & **Half-Red** & \(p\) & **Red** & **Half-Red** & \(p\) \\ \hline Respiration rate (mL CO\({}_{2}\) kg\({}^{-1}\) h\({}^{-1}\)) & 16.74 & 14.70 & ns & 15.33 & 13.61 & ns & 16.50 & 14.00 & ns \\ Tittrable acidity (\% citric acid) & 0.78 & b & 0.99 & a & ***. & 0.86 & b & 1.00 & a & ***. & 0.76 & b & 0.97 & a & ***. \\ pH & 3.56 & a & 3.31 & b & ***. & 3.44 & a & 3.27 & b & ***. & 3.54 & a & 3.46 & b & * \\ Total soluble solids (*Brix) & 9.61 & a & 8.37 & b & ***. & 9.83 & a & 8.50 & b & ***. & 10.17 & a & 9.73 & b & **. \\ Antioxidant activity (mg Trolox 100 g\({}^{-1}\) fw) & 314.72 & a & 345.06 & b & ***. & 308.12 & b & 339.1 & a & * & 287.5 & b & 347.25 & a & ***. \\ Total phenols (mg GAE 100 g\({}^{-1}\) fw ) & 175.91 & a & 207.29 & b & * & 191.46 & b & 218.05 & a & * & 183.42 & b & 207.84 & a & * \\ \hline \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 (LSD) test. Significance: ns = not significant; **
* significant for \(p\)\(\leq\) 0.001;
* significant for \(p\)\(\leq\) 0.01;
* significant for \(p\)\(\leq\) 0.05. GAE is Gallic Acid Equivalent.  
\end{table} 
Table 1: Physical and chemical parameters measured in strawberries cv “Sabrosa” at two different ripening stages (half-red or red) and at three harvest times (H1, H2, H3). fraction is substantially dominated by a few compounds, whereas a multitude of other metabolites occur at a minor abundance [23; 24]. The RP-HPLC separation of phenolic compounds in strawberry methanol extracts has been monitored at multiple wavelengths. Typical RP-HPLC chromatograms of extracts from red (left A) and half-red (right B) \"Candonga\" strawberries are shown in Figure 2. In particular, in Figure 2, the HPLC chromatograms recorded at 280 nm for the general detection of phenolic compounds, at 360 nm for the selective detection of flavonoids and EA and at 520 nm for the diagnostic detection of anthocyanins are compared. The main HPLC peaks were assigned in Table 2, based on the converging indications coming from previous identification of strawberry phenolics [23; 24; 25] UV-Vis spectra acquired with the DAD, high-resolution MS and MS/MS spectra. In agreement with previous data, \(p\)-couamyl-hexoside (peak 1, P1) was the most abundant hydroxycinnamic acid derivative of strawberry, better detected at 320 nm (not shown) because of the characteristic absorbance band centered at 315 nm. In half-red strawberries, P1 was 3-/4-fold lower than in the red samples. Similar to other strawberry cultivars, the anthocyanin profile of the strawberry is substantially conserved among the cultivars [25]. Pelargonidin-3-\(O\)-rutinoside (P4) was the prevalent anthocyanin both in red and half-red strawberry samples, followed by less abundant pelargonidin-3-\(O\)-glucose (P3) and cyanidin-3-\(O\)-glucose (P2). However, the concentration of anthocyanins in unripe fruits was nearly half than the red counterpart.