# Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (_Hylocereus_) Species
## 3 Results
### Total Phenolic Content and Antioxidant Capacity  
Total phenolic content (TPC) and antioxidant capacity (TAC) of red-purple and white-fleshed pitaya species were shown in Table 1. TPC of red and white-fleshed pitaya were 16.66 to 17.11 mg GAE/100 g FW, respectively (Table 1). The red-purple fleshed pitaya fruits have a higher value of TPC than the white-fleshed ones (Table 1). [PERSON] et al. [3] reported that TPC of the different pitaya varieties were between 32.5 and 42.5 mg GAE/100 g FW. Previously pitaya fruit was reported to have significantly higher total phenolic content compared to the other tropical fruits [51]. [PERSON] and [PERSON] [10] reported that TPC in the pitaya fruit flesh is 28.65 mg GAE/100 g FW. [PERSON] et al. [16] revealed that TPC varied from 9.12 to 13.3 mg/g in different Hylocereus spp. fruits. [PERSON] et al. [5] also reported that Hu and Hp varieties had TPC between 3.75 and 19.72 mg GAE/100 g. [PERSON] [52], reported that the TPC in all samples was higher in water than methanol extracts and red-fleshed pitaya had the highest TPC, followed by white and yellow fleshed pitaya. The results for TPC in the fruits were consistent with [PERSON] [53], and [PERSON] [54], who observed higher concentration of these compounds in red-fleshed than in white ones. [PERSON] et al. [55] found that the TPC was 40.68 mg GAE/100 g FW in pitaya peel. Antioxidant assays including DPPH and ABTS were used to measure the radical scavenging ability, while FRAP and TAC assays were used to determine the reducing power of samples. The DPPH assay is one of the non-specific free radical scavenging assays as it measures free radicals scavenged by both phenolic and non-phenolic compounds, including gallic acid [56]. The findings indicated that the red-fleshed pitaya fruits have the higher TAC (46.81%) while white-fleshed has the lower TAC (38.16%) as we compare two samples (Table 1). [PERSON] et al. [3 reported that the TAC in fruits of the different pitaya varieties were found to be 36 and 70.1% in the flesh. [PERSON] et al. [57] studied the TAC of red pitaya. According to them, peel and flesh were both rich in phenolics and good sources of antioxidants. Some of the authors previously reported that the antioxidant capacity of pitaya flesh is due to the presence of both betalains and phenolic compounds, which have the ability to donate their electrons and to scavenge the ABTS cation radical, as Trolox does [58; 59]. However, the interactions that occur between different types of compounds within each group, to express a particular antioxidant capacity, are not fully understood. The TAC of the most abundant betalain present in the fruit does not always correlate with the TAC expected for the whole fruit, but rather is the result of the interaction of all the antioxidant compounds it contains. Both betalains and phenolic compounds could influence the TAC of pitaya fruit. [PERSON] et al. [16] reported that antioxidant capacity of purple-fleshed pitaya was based mostly on betalains and other non-betalainic phenolics such as gallic acid and acetylcumarins. [PERSON] et al. (2017) also reported that the TAC in pitaya pulp was highly variable and found between 2.41 and 9.21 mol Trolox/g FW determined by the ABTS. [PERSON] and [PERSON] (2017) also reported that _H. undatus_ exhibited the highest RSA activity (63.44%) of DPPH. [PERSON] et al. (2016) and [PERSON] et al. (2017) reported high antioxidant capacity in their studies in red, white and yellow-fleshed pitaya fruits, respectively. The antioxidant capacity of pitaya fruit has been noted to be higher than some other tropical fruits such as mango, lychee, longan and papaya (2017). Oxygen radical absorbance capacity (ORAC) varies in the range of 8.80-11.30 mol/g depending on the variety and bioactive component profile ([PERSON] et al., 2017). The findings of our study on red-purple and white-fleshed pitaya are generally compatible with the findings of other researchers, but some values were found to be higher and some lower.