Bound galloylated compounds in persimmon upcycled dietary fiber modulate microbial strains associated to human health after in vitro digestion

Persimmon byproduct upcycling was performed by solvent-assisted extraction (SAE) to obtain dietary fiber (DF). The effect of SAE on DF modulation was studied on specific beneficial and pathogenic strains before and after the in vitro digestion process. Overall, digested DF samples extracted using acetone as a solvent (dCET) showed higher (p < 0.05) prebiotic activity scores (PASs) in beneficial bacteria such as Bifidobacterium bifidum, Lactobacillus casei, Lactococcus lactis, and Streptococcus salivarius. Moreover, dCET reduced the tested pathogenic strain populations. Initial cell attachment (ICA) inhibitory activity on biofilm formation by Pseudomonas putida, Staphylococcus aureus and Bacillus subitilis was observed for dCET, as well as inhibition of preformed (PFB) S. aureus biofilms. dCET combined with the antibiotics kanamycin (K) or gentamycin (G) exhibited synergistic effects against all tested pathogens, displaying bactericidal effects against S. aureus. High-performance liquid chromatography (HPLC-DAD) analysis showed that after hydrolysis, the released gallic acid could have been responsible for the antimicrobial properties registered in DF from the persimmon byproduct. The obtained results provided information about the potential of upcycled persimmon fiber fractions as possible prebiotics, although further research must be performed with complex microbial populations and in vivo studies.