Centesimal Composition, Bioactive Compounds, and Antimicrobial Properties of White ( Hylocereus undulatus ) and Red ( Hylocereus polyrhizus ) Pitayas

This study investigated the centesimal composition, physicochemical properties, bioactive compounds, antimicrobial activity, and anti-quorum sensing (QS) potential of red pulp (RP; Hylocereus polyrhizus) and white pulp (WP; Hylocereus undulatus) pitayas. Both pulps exhibited high moisture content and low protein levels, with ash contents of 0.78% (RP) and 0.70% (WP), titratable acidity of 0.26% for both, and pH values of 5.75 (RP) and 5.12 (WP). RP pitaya presented a higher total phenolic content and contained 3.15 mg/100 g of betalains. Antioxidant capacity differed according to the assay employed: RP showed higher activity in the ABTS•+ and β-carotene/linoleic acid methods, whereas WP exhibited greater radical scavenging capacity in the DPPH• assay. LC-MS/MS analysis revealed phyllocactin as the major betalain in RP pitaya, along with 4'-O-malonyl-betanin and isophyllocactin. Four flavonoids were identified, with quercetin 3-rutinoside as the predominant compound. Both extracts displayed mild antimicrobial activity against foodborne pathogens and inhibited violacein production by Chromobacterium violaceum, indicating anti-QS activity. However, no inhibitory effects were observed on swarming motility or biofilm formation under subinhibitory concentration. Overall, the results highlight pitaya pulps as sources of bioactive compounds with antioxidant, antimicrobial, and anti-QS properties, supporting their potential application in food systems and as natural ingredients for microbial control strategies.