Characterization of molar mass and conformation of relevant (non-)starch polysaccharides in cereal-based beverages

Arabinoxylans, β-glucans, and dextrins influence the brewing industry's filtration process and product quality. Despite their relevance, only a maximum concentration of β-glucans is recommended. Nevertheless, filtration problems are still present, indicating that although the chemical concentration is essential, other parameters should be investigated. Molar mass and conformation are important polymer physical characteristics often neglected in this industry. Therefore, this research proposes an approach to physically characterize enzymatically isolated beer polysaccharides by asymmetrical flow field-flow fractionation coupled to multi-angle light scattering and differential refractive index detector. Based on the obtained molar masses, root-mean-square radius (r_rms from MALS), and hydrodynamic radius (r_hyd), conformational properties such as apparent density (ρ_app) and r_rms/r_hyd can be calculated based on their molar mass and size. Consequently, the ρ_app and r_rms/r_hyd behavior hints at the different structures within each polysaccharide. The r_rms/r_hyd 1.2 and high ρ_app values on low molar mass dextrins (1-2·10⁵ g/mol) indicate branches, while aggregated structures at high molar masses on arabinoxylans and β-glucans (2·10⁵ -6·10⁶ g/mol) are due to an increase of ρ_app and a r_rms/r_hyd (0.6-1). This methodology provides a new perspective to analyze starch and non-starch polysaccharides in cereal-based beverages since different physical characteristics could influence beer's filtration and sensory characteristics.