Xylitol production from brewer’s spent grain via Pichia fermentans fermentation: optimization, scaling, and isolation

The primary aim of this study was to investigate the novel application of brewer’s spent grain (BSG), a waste byproduct from the brewing industry, as sustainable and cost‐effective feedstock for xylitol production using the yeast Pichia fermentans. The process encompassed fermentation optimization, scale‐up, and then downstream processing to produce xylitol. Shake flask fermentation was employed to determine optimal conditions, evaluating key parameters including inoculum concentration (12.5%), feedstock (50%), pH (7.0), temperature (30°C), incubation time (96 h), and agitation speed (150 RPM) with a maximum xylitol production of 32.74 g/L. The yield of xylitol increased to 34.57 g/L by scaling up in an 8‐L bioreactor within an incubation time of 72 h. Downstream processing, including centrifugation, charcoal treatment, and ethanol purification was performed successfully, recovering xylitol crystals with a purity of 85.90%. Characterization using X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and high‐performance liquid chromatography (HPLC) confirmed the purity and composition of crystals. This research highlights the economic and environmental advantages of utilizing BSG for xylitol production, offering a sustainable route over conventional substrates.