Pectic Polysaccharides from Dragon Fruit Peel: Structure-Function Relationships and Emerging Potential in Synbiotic...

The valorization of agro-industrial byproducts is attracting attention due to its potential to support circular bioeconomy development in food systems. Dragon fruit (Selenicereus spp.) peel, representing approximately one-third of total fruit mass, is an underutilized biomass that is high in pectin content. Unlike standardized commercial citrus and apple pectins, pectin from dragon fruit peel exhibit variability in their galacturonic acid content, degree of esterification, molecular weight, and rhamnogalacturonan-I branching structure, which are dependent on how the pectin is extracted. These structural attributes influence the solubility, rheological properties, gelation mechanisms, emulsifying capacity, and water-holding properties. There is emerging evidence that rhamnogalacturonan-I-enriched fractions promote the growth of beneficial microorganisms and may also increase the in vitro production of short-chain fatty acid, thereby exhibiting potential prebiotic activity. In addition, low methoxyl pectin has been shown to provide excellent properties for the calcium-mediated encapsulation of probiotics, as well as for pH-sensitive release in the gastrointestinal tract, thus supporting the synbiotic concept. The purpose of the current paper is to provide an overview of recent findings related to extraction technologies, structural characterization, structure-function relationship, fermentation behavior, potential delivery of probiotics, and the regulatory requirements for using dragon fruit peel pectin in the development of functional foods.