Efficacy of pre-treatment of insoluble fibres derived from persimmon (Diospyros kaki) fruit by-products to promote growth of beneficial human colonic bacteria

Abstract

Persimmon by-products are valuable sources of dietary fibre and phytochemicals, offering potential benefits for circular nutrition and economic sustainability. This study investigates the impact of different pre-treatment technologies on persimmon polysaccharides, particularly those rich in non-starch polysaccharides (NSP), and their potential to support the growth of representative commensal human gut bacteria. Persimmon by-products were pre-treated to obtain insoluble fractions by alkaline/acid hydrolysis (HPF), vacuum expansion (VPF), sonication (SPF), fermentation (FPF) and vacuum expansion/fermentation (VFPF), and characterized by their NSP profile, free sugars, anthocyanidins, bound and free polyphenols, and mineral content. The pre-treatments,

especially SPF, significantly affected the composition of the polysaccharides. A reduction in NSP and poly- phenolic content in SPF was observed; an increment in the levels of free sugars and anthocyanidins compared to

other treatments was also noted. Following sterilisation with ethanol or heat, the by-product samples were incubated with eight representative human gut bacterial strains. Sonication enhanced the utilisation of persimmon fibres by bacterial strains, especially Faecalibacterium prausnitzii and Bacteroides thetaiotaomicron. Results also showed a potential selective effect of the samples since Escherichia coli did not proliferate the most in

the samples. Further analysis revealed that HPF, SPF, and VPF were most suitable for consumption by Rumi- nococcus champanellensis (human-originated strain), as opposed to R. flavefaciens (ruminant strain). These find- ings highlight the potential of persimmon polysaccharides, especially those from post-hydrolysis treatments, as

substrates for growth of beneficial key gut bacteria, emphasizing their suitability for human consumption to meet dietary targets and promote health while supporting a circular economy and greener food production.