Structural Characterization and Prebiotic Effects of Passiflora edulis Sims Peel Polysaccharide-Zinc

This study aimed to characterize the structure of Passiflora edulis Sims peel polysaccharide-zinc (WPEP-Zn) and its prebiotic effects. The structural characteristics of WPEP-Zn were determined using Fourier transform infrared spectrometer, X-ray diffractometer, scanning electron microscope, Congo red test, and thermogravimetric analyzer. The WPEP-Zn was used as carbon source to study its prebiotic effects on Lactobacillus plantarum, Lactobacillus delbrueckii (subsp.) bulgaricus, Lactobacillus brevis, and Streptococcus thermophilus. The results showed that WPEP-Zn had sugar and uronic acid content of 23.26% and 50.46%, respectively, whereas the zinc content was 10.64 mg/g. It had a triple helix structure compared with the Passiflora edulis Sims peel polysaccharide (WPEP). Its relative crystallinity decreased, the infrared absorption peak changed, the morphological structure altered, and the thermal stability enhanced. The optimal concentrations of WPEP-Zn used to promote the growth of the four bacteria strains were 3%, 2%, 2%, and 2%, respectively. The prebiotic effects of WPEP-Zn on L. plantarum, L. delbrueckii (subsp.) bulgaricus, and L. brevis were lower than WPEP, but its prebiotic effect on S. thermophilus was higher than the WPEP. The findings revealed the prebiotic effect of WPEP-Zn. The study on WPEP-Zn provided a basis for developing new polysaccharide-zinc supplements and the effective utilization of passion fruit resources.