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Interaction between cereal beta-glucan and gastric mucin L. Ringier (1), P. Fischer (1), L. NYSTROEM (1). (1) ETH Zurich, Zurich, Switzerland Dynamic interaction of cereal beta-glucan and gastric mucin was studied as a potential new dynamic mechanism of action responsible for the regulation of absorption of nutrients such as cholesterol and glucose. The well-established health benefits of beta-glucan are generally related to its capability to increase viscosity of the gut contents. However, our study  demonstrates that the mixture of mucin and beta-glucan can form stronger gels than mucin alone. Gastric mucin was extracted from fresh porcine stomachs, homogenized in buffer solution, fractionated using ultracentrifugation and dialyzed. Beta-glucan samples from oat and barley (concentrated extracts, purified commercial samples, and oxidized beta-glucans) were mixed with the freshly prepared mucin gel, and after incubation the viscoelastic properties of the gels were measured. Addition of 2% of low molecular weight barley beta-glucan to mucin gel increased the storage modulus (G’) by an order of magnitude from 1 Pa to 10 Pa. Similarly, an increase in the gel strength was observed with beta-glucans that were oxidized through hydroxyl radical treatment (addition of 20 mM of hydrogen peroxide and 100 µM ferrous ions, incubation up to 24h at 55°C). These results demonstrate that low molecular weight beta-glucan, which also has a low viscosity, may have an active interaction with the mucosal layer in the gastrointestinal tract, and that these interactions may be further enhanced by oxidation that introduces new functional groups to the polymer chain. This study may lead to a paradigm shift that highlights the importance of active intermolecular interactions between soluble dietary fibres and the gastrointestinal mucin, and it  provides explanations and a new mechanism of action for the low viscosity fibres that have been previously considered as less active in health promoting properties. View Presentation