Dragon fruit juice was diluted with McIlvaine buffer (pH 6.5) until a maximum absorption of 1.00±0.05 was reached
(Herbach et al. 2007). McIlvaine buffer was prepared from 0.1Mcitric acid (30mL) and 0.2Msodiumphosphate dibasic
(70mL) (Jamilah et al. 2011).