Comparison of nutritional traits of pitaya (dragon fruit) varieties

Pitaya or Dragon fruit is originated from South America and belongs to the Cactaceae botanical family. The skin is covered with 'scales' and comes either as a red-skinned or yellow-skinned variety. The red-skinned variety can has red (Hylocereus costaricensis) or white (Hylocereus undatus) pulp, while yellow-skinned variety (Selenicereus megalanthus) is available only in white pulp. The pitaya consumption has been increasing in recent years, due to its exotic appearance and sweet taste, and can be found as fresh fruit or and processed in form of sorbet, sorbet, beverages, among others. Still there few studies involving this fruit and its functional and nutritional properties, hence, this study aimed to compare the three main pitaya varieties for concentration of sugars, organic acids, total phenolic compounds and antioxidant activity. The extraction of sugars and organic acids was performed by ultrasound (Elmasonic 60H), using 80 Hertz by 20 minutes at 35°C. The separation of these compounds was carried by HPLC and quantification was performed by external standarlization using: sucrose, glucose, fructose, malic, citric and ascorbic (Sigma-Aldrich, purity> 99%). For the extraction of phenolic and antioxidant compounds was prepared a suspesion with 0.200 g of the pulp in 5.0 mL of 80% (v/v) methanol, which centrifuged at 4000 rpm and supernatant separated for analyzes. The quantification of total phenolic compounds was carried by the Folin-Ciocalteau method, using spectrophotometer (Thermo Biomat 3) fixed in 720 nm wavelenght, the results were expressed in mg Gallic acid equivalent (GAE) per 100 g pulp. The antioxidant activity was estimated by DPPH radical scavenging by a spectrophotometry at 517 nm, and results were expressed as Trolox equivalent antioxidant capacity (TEAC) per 100 g pulp. Data were submitted to the F test and the Tukey test, using α = 5%, in addition to the main components analysis, using the R software. The pitaya red-skinned and white pulp had the highest concentration of total sugars (98,33 mg/g), composed only glucose and fructose, whereas the fruit of yellow-skinned contained only sucrose, and the pitaya red-skinned and white pulp showed the highest glucose content (59.52 mg / g). Ascorbic acid was not detected in pitaya pulps, and found only citric and malic acids, in which the red pulp fruit showed the highest concentration of malic acid, compared to the yellow-skinned fruit, 8.33 and 3.97 mg / 100g, respectively. The red pulp fruit had the highest content of total phenolic compounds and antioxidant capacity, 33.75 mg GAE / 100 g and 175.51 μmol TEAC / 100 g, respectively. Thus, from the nutraceutical point of view, it is recommended to use the pitaya red-skinned and red pulp, while the yellow-skinned and the red-skinned and white pulp are a technologically interesting options due to the higher content of reducing sugars and less acidity.