Evaluation of a Novel Phosphorylated Red Dragon Fruit Peel Pectin for Enhancement of Thermal Stability and Functional Activity

Red dragon fruit peel, as a fruit waste, is rich in plant-based nutritional pectins that can be applied as food additives. The present study aims to characterize a novel phosphorylated red dragon fruit peel pectin (PRDFP-P) and to explore its functional activities. The thermal analysis, morphology analysis, antibacterial, antioxidant and antitumor activities of PRDFP-P were evaluated. The results showed that the phosphorylated derivative PRDFP-P had typical phosphate groups. Compared with the native red dragon fruit peel pectin (PRDFP), PRDFP-P possessed superior thermal stability and exhibited significant inhibition effects on Escherichia coli and Staphylococcus aureus. Moreover, the phosphate groups on the derivative PRDFP-P chains remarkably enhanced the scavenging ability of hydroxyl radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. In addition, PRDFP-P showed a significant inhibition effect on growth of human hepatic carcinoma cells (HepG2) and the IC₅₀ value was determined to be 248.69 μg/mL (P < 0.05). Our results suggested that the phosphorylated derivative PRDFP-P might be potentially applied as stabilizing, thickening and gelling agents with functional activities in the food industry.