Hemicellulose enriched dietary fiber from Asian pear pomace: Enzymatic approach for assessing potential prebiotic and immunomodulatory properties

Abstract

Pear pomace, a byproduct of juice production, contains valuable but underutilized dietary fibers. Our focus was on enzymatically treating this fiber to produce a hemicellulose-rich powder. The pear pomace was sieved to remove non-edible stone cells. Among the 11 commercial enzymes, Trichoderma reesei-derived enzyme with cellulase and β-glucanase activities was found optimal for improving the hemicellulose content. The enzyme-treated pomace dietary fiber (PDE) exhibited a 2.5-fold increase in hemicellulose contents, lower and uniformed particle sizes, 8-fold higher solubility, and 3-fold higher water-/oil-holding capacity than the pear pomace powder. The highest production yield of PDE (74.5 %) and hemicellulose content (21.1 %) were observed on incubating 1 % (w/v) enzyme and 8 % (w/v) pear pomace for 24 h. PDE showed prebiotic properties by promoting the growth of Bifidobacterium infantis by 9 % and inhibiting the growth of Salmonella typhimurium by 50 % compared to positive control (β-glucan) in a co-culture system. The anti-inflammatory effect of PDE was verified by ELISA. The results revealed reduced secretion of nitric oxide (30 %), TNF-α (71 %), and IL-6 (46 %) in LPS-stimulated RAW 264.7 cells. Moreover, qRT-PCR confirmed that PDE enhanced cytokine production upon treatment of cells with an immunosuppressant by regulating the nuclear factor kappa B signaling pathway.