Limitation of non-starch polysaccharides concentration as a filterability predictor in unfiltered bottom-fermented beers

Filterability is a key parameter of process efficiency in beer production, yet its relationship with non-starch polysaccharides (NSPs), particularly arabinoxylans, has received little attention. This study examined how the NSPs’ concentration and macromolecular characteristics such as molar mass, polydispersity, and molecular size affect the filterability of 36 commercially produced unfiltered bottom-fermented beers. β-glucan and arabinoxylan concentrations were quantified using chemical analysis. Macromolecular characteristics were determined using asymmetric flow field-flow fractionation coupled with multi-detector systems (AF4-MALS-RI-DAD). Filterability was assessed from the specific filtrate volume (F spez ) using an in-house Raible test. Although all samples met the β-glucan concentration quality criteria, significant variability in F spez values was observed. Statistical analysis revealed a negative association between β-glucan concentration and F spez , while arabinoxylan concentration indicated no such relationship. Higher weight-average and z-average molar mass ( M w , M z ), broader polydispersity (PDI) within fraction 3 (high molar mass fraction) and a larger proportion of molecules above 500×10 3 g/mol negatively affected F spez . These findings demonstrate that macromolecular properties can decisively influence the filterability of bottom-fermented beers, indicating that β-glucan concentration alone may be insufficient as the only determining quality criterion. • Breweries assess filterability entirely based on established concentration values. • Beer filterability can vary even when quality specifications are met. • Unfiltered beers were assessed using asymmetric flow field-flow fractionation. • A molar mass exceeding 25×10 4 g/mol and broad polydispersity reduced filterability. • Molar mass provides deeper insight into filterability beyond concentration.