Pomelo (Citrus grandis (L.) Osbeck) sponge layers as a potential source of soluble dietary fiber: Evaluation of its physicochemical, structural and functional properties.

Pomelo sponge layer (PSL) had been considered as a potential source of soluble dietary fiber (SDF), while they were mostly disposed of as waste. To promote high-value utilization of pomelo wastes, this study extracted SDF from PSL of six varieties of pomelo, and their physicochemical, structural and functional properties were investigated. Results indicated that all PSL-SDFs showed good physicochemical and functional properties. Among them, PSL-SDF from grapefruit (GRSDF) showed better water holding capacity and swelling capacity, whereas Shatian pomelo PSL-SDF and Guanxi pomelo PSL-SDF had the highest thermal stability and oil holding capacity, respectively. Furthermore, compared with other PSL-SDFs, GRSDF displayed the lowest hydrolysis degree coupled with the best antioxidant and probiotic growth-promoting abilities. Finally, the correlation analysis showed that multiple beneficial effects of PSL-SDFs were markedly associated with their molecular weight and the concentrations of total phenolic, total flavonoids, rhamnose, galacturonic acid, glucose and arabinose. Collectively, these findings contributed to a better understanding of the physicochemical and functional properties of SDFs extracted from different PSLs, which provided a scientific basis for the development of PSL-SDFs into functional foods.