Physicochemical, structural, and rheological characteristics of pectic polysaccharides from fresh passion fruit (Passiflora edulis f. flavicarpa L.) peel

In this paper, four pectic polysaccharides (PFP-T, PFP-U, PFP-M, and PFP-UM) were obtained from fresh passion fruit (Passiflora edulis f. flavicarpa L.) peel by three-phase partitioning (TPP), ultrasound assisted TPP (U-TPP), microwave assisted TPP (M-TPP), and sequential ultrasound-microwave assisted TPP (UM-TPP) methods, respectively. Results demonstrated that ultrasound/microwave treatments before TPP separation obviously affected the yields, physicochemical properties, and structural characteristics of these pectic polysaccharides, and improved their rheological properties. The PFP-U obtained by U-TPP had the highest molar mass (436.9 × 103 g mol−1), the shortest homogalacturonan backbone, and the most rhamnogalacturonan side chains with a relatively rigid chain and possessed the best thermal stability and viscoelastic behavior. The PFP-UM obtained through UM-TPP showed the highest contents of total sugar (74.88%) and uronic acid (68.22%) with a flexible random coil, and exhibited the best steady-state fluid property. Therefore, our findings provide a promising technical strategy for producing pectic polysaccharides with desired functionalities from fresh fruit peels.