# Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (_Hylocereus_) Species
## 3 Results
### Phenolic Compounds  
Phenolic compounds are an excellent source of antioxidants that play an important role in protecting human health. These compounds also contribute to the taste, color, and health benefits of plants ([PERSON] et al., 2017; [PERSON] et al., 2017). Phenolic compounds play a major role in contributing to overall antioxidant capacity ([PERSON] et al., 2017). There are very limited and almost no reports of the presence of individual phenol compounds in fruits of cacti species. Here, identification and quantification of individual phenolic compounds of _Hu_ (red pitaya with white flesh) and the _Hp_ (red pitaya with red flesh) performed by HPLC and the contents of phenolic compounds are provided in Table 2. According to the results, seven phenolic compounds were identified. Quercetin was dominant--3.43 mg/100 g in red-fleshed pitaya and 3.09 mg/100 g in white-fleshed pitaya. Gallic acid, kaempfer, ellagic acid, _p_-coumaric acid, caffeic acid and myricetin content were 0.17 mg/100 g; 0.21 mg/100 g, 0.15 mg/100 g, 0.16 mg/100 g, 0.12 mg/100 g and 0.33 mg/100 g in red-fleshed pitaya fruits, respectively. In white-fleshed  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Variety**} & \multicolumn{4}{c}{**Sugar**} & \multicolumn{2}{c}{**Total Phenol**} & \multirow{2}{*}{**DPPH\%**} \\ \cline{2-2} \cline{4-6}  & **Glucose** & & & & & **\#PUH** \\ \hline Red-fleshed & 7.52 \(\pm\) 0.74 & 0.03 \(\pm\) 0.04 & 3.70 \(\pm\) 0.50 & 11.25 \(\pm\) 1.27 & 17.11 \(\pm\) 0.38 & 46.81 \(\pm\) 2.93 \\ White-fleshed & 5.22 \(\pm\) 0.39 & 0.05 \(\pm\) 0.02 & 4.97 \(\pm\) 0.48 & 10.24 \(\pm\) 0.85 & 16.66 \(\pm\) 0.56 & 38.36 \(\pm\) 0.2.67 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The content of sugars, total phenol, total antioxidant capacity of pitaya species (_Hyloereus_ spp.).  
pitaya fruits, gallic acid, kaempfer, ellagic acid, \(p\)-coumaric acid, caffeic acid and myricetin content were 0.16 mg/100 g; 0.26 mg/100 g, 0.10 mg/100 g, 0.16 mg/100 g, 0.13 mg/100 g and 0.47 mg/100 g, respectively (Table 2).  
[PERSON] et al. [64] reported 150.46 mg of phenolic compounds (betalains, gallic acid, and betacyanins) per 100 g dry weight in the _Hylocereus_ species. [PERSON] et al. [16] reported that gallic acid was observed in all the genotypes, with higher amounts in 'Rosa' and lowest in 'Orejona' pitaya varieties.  
The same authors implied that gallic acid was identified for the first time in pitaya fruits and the phenolic profiles generally differed between genotypes. Several flavonoids such as catechin, epicatechin, quercetin, myricetin, kaempfer, and rutin were detected and quantified in pitaya seeds by [PERSON] et al. [69]. According to their results, catechin (3.60 mg/g dw), quercetin (1.31 mg/g dw) and myricetin (0.63 mg/g dw) were found to be the major flavonoids, respectively. [PERSON] et al. [70] reported that red pitaya fruits contain gallic acid, pyrocatheunic, vanillic acid, caffeic acid, and \(p\)-coumaric acid. In another study, [PERSON] et al. [11] reported that the \(p\)-coumaric acid, syringic acid, caffeic acid, vanillic acid, pyrocathehunic and gallic acid in flesh and peels of red pitaya fruits were 0.78 mg/100 g, 0.08 mg/100 g, 0.08 mg/100 g, 0.64 mg/100 g, 0.93 mg/100 g and 0.25 mg/100 g, respectively. [PERSON] et al. [56] reported higher content of quercetin, myricetin, kaempfer in pitaya than our results. Pitaya flesh (pulp) was also found to be abundant in phenolic acids while quercetin was dominantly detected. Previously, flavonoids including kaempfer and quercetin derivatives were detected and quantified in pitaya fruit peels as well [71; 72].