Phytochemical properties, antioxidant potential and fatty acids profiling of three dragon fruit species grown under sub-tropical climate

Abstract

The physical, biochemical and antioxidant properties of one white pulped (Hylocereus undatus; DG-I) and two red pulped dragon fruit species (H. polyrhizus, DG-II; H. costaricencis, DG-III) grown under sub-tropical conditions of north-west India were determined. Fruit size, fruit weight, pulp weight and pulp: peel ratio was significantly higher in DG-III, though the fruit numbers and yield per pillar was significantly less than other species. The pH, TSS, acidity, total sugar, reducing sugars and moisture content in all the species varied between 4.78-5.72, 8.63-9.31 oBrix, 0.30-0.56%, 6.64-6.91%, 4.60-4.76% and 83.44-85.82%, respectively. Total phenols and flavanols content in DG-I was 24.04 mg GAE 100 g−1 and 14.54 mg RE 100 g−1, whereas in red pulped it was significantly higher; varying between 49.12-56.40 mg GAE 100 g−1 and 30.41-31.10 mg RE 100 g−1 fruit pulp, respectively. β-carotene values in red pulped species DG-II and DG-III were 47.48 and 43.82 µg 100 g−1, respectively compared to corresponding values of 1.96 µg 100 g−1 in DG-I, a white pulped dragon fruit. Similarly, DPPH-RSC, FRAP, CUPRAC and ABTS values for red pulped dragon fruit ranged between 238.98-262.04 µmol 100 g−1, 358.8-386.40 µmol TE 100 g−1, 830.40-917.0 µmol TE 100 g−1 and 571.4-589.60 µmol 100 g−1, respectively in DG-II and DG-III in comparison to respective values of 108.75 µmol 100 g−1, 192.6 µmol TE 100 g−1, 525.6 µmol TE 100 g−1 and 400.2 µmol 100 g−1 in DG-I. The β-lain, responsible for imparting red colour in DG-II and DG-III was absent in white pulped DG-I. Seed oil content in both groups of dragon fruit varied between 31.90-33.5% with highest proportion of an essential fatty acid, linoleic acid (46.32-47.96%). In conclusion, red pulped dragon fruit has a considerably higher antioxidative potential than white one and these species may play a vital role in ensuring nutritional security for millions of people in developing nations.