Nutritional Analysis of Red-Purple and White-Fleshed Pitaya (Hylocereus) Species

Abstract

Pitaya is one of the most preferred and produced tropical fruit species recently introduced to the Mediterrranean region in Turkey. Due to its nutritional fruits with high economic value, the popularity of pitaya increases steadily in Turkey as an alternative crop. No detailed nutritional analysis has been undertaken in Turkey so far on fruits of the pitaya species. In this study, we determined and compared some nutritional parameters in fruit flesh of two pitaya (dragon fruit) species (Hylocereus polyrhizus: Siyam and Hylocereus undatus: Vietnam Jaina) grown in the Adana province located in the eastern Mediterranean region in Turkey. The individual sugars, antioxidant activity, total phenolic content, phenolic compounds and volatiles were determined for the first time in Turkey on two pitaya species. The results showed that total phenol content and antioxidant capacity are notably higher in red-fleshed fruits than white-fleshed ones and the predominant phenolic compound in fruits of both species was quercetin. The total sugar content and most of the phenolic compounds in fruits of two pitaya species were similar. A total of 51 volatile compounds were detected by using two Solid Phase Micro Extraction (SPME) fibers, coupled with Gas Chromatography Mass Spectrometry (GC-MS) techniques, and more volatile compounds were presented in the white-fleshed species. Total phenolic content (TPC) of the red-fleshed and white-fleshed pitaya species were 16.66 and 17.11 mg GAE/100 g FW (fresh weight). This study provides a first look at the biochemical comparison of red-fleshed and white-fleshed pitaya species introduced and cultivated in Turkey. The results also showed, for the first time, the biochemical content and the potential health benefit of Hylocereus grown in different agroecological conditions, providing important information for pitaya researchers and application perspective.

Keywords: HS-SPME/GC-MS; phenolic compounds; pitaya (Hylocereus spp.) sugars; volatiles.

Figure 1

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for phenolic compounds in red-white pitaya.

Figure 2

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for sugars in red-white pitaya.

Figure 3

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for Alcohols from volatile compounds in red-white pitaya. alc1: 1-Hexadecanol, alc2: 1-Tetradecanol, alc3: dimethyl-Silanediol, alc4: <2-ethyl->Hexanol, alc5: Lauryl alcohol, alc6: Pentadecanol, alc7: Tridecyl alcohol.

Figure 4

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for ketones from volatile compounds in red-white pitaya. k1: 1-hydroxy- 2-Propanone,k2: 1-(2-furanyl)- Ethanone, k3: 2,3-Butanedione, k4: 2-Propanone, k5: 5-hexyldihydro- 2(3H)-Furanone, k6: diphenyl- Methanone, k7: Dodecalactone; R.Spme: Red Spme; B.Spme: Blue Spme.

Figure 5

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for aldehydes from volatile compounds in red-white pitaya. ald1: 2 octenal, ald2: 2,4 nonadıenal, ald3: 2-Decenal, (E)-, ald4: 2-furancarboxaldehyde, ald5: 2-heptenal, (Z)-, ald6: 2-oxo- Propanal, ald7: 3-methyl-Benzaldehyde, ald8: caprylaldehyde, ald9: hexanal, ald10: Non-2(E)-enal, ald11: nonanal, ald12: octanal, ald13: Trans-2-Dodecenal, ald14: trans-2-Undecenal.

Figure 6

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for esters from volatile compounds in red-white pitaya. e1: 1,2-Benzenedicarboxylic acid, diethyl ester, e2: Acetic acid, ethyl ester.

Figure 7

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for acids from volatile compounds in red-white pitaya. ac1: 2-Acetonyl-3-cyano-2,3-dimethylcyclobutane-1-carboxylic acid, ac2: acetic acid, ac3: anhydride acetic acid, ac4: caprylic acid, ac5: Carbamic acid, monoammonium salt, ac6: decanoic acid, ac7: dodecanoic acid, ac8: heptanoic acid, ac9: hexanoic acid, ac10: nonanoic acid, ac11: octanoic acid, ac12: pentadecanoic acid, ac13: tetradecanoic acid.

Figure 8

Biplot graph (scores and loading plots) obtained from Principal Component Analysis for other compounds from volatile compounds in red-white pitaya. oc1: methyl isocyanide, oc2: 1-methyl->Piperidine, oc3: 2,6-bis(1,1-dimethylethyl)-4-methyl- Phenol, oc4: 1,1′-oxybis- Octane, oc5: 2,6,10,14-tetramethyl- Hexadecane, oc6: tetranitro- Methane, oc7: Tridecane.