Gelation of cereal β-glucan after partial dissolution at physiological temperature: Effect of molecular structure

Abstract

Cereal β-glucan is noted for its health benefits which are directly linked to its rheological properties. In this work, the gelation potential of cereal β-glucans with varying fine structure was evaluated after dissolution at physiological temperature. β-Glucans from 12 oat and 12 barley samples were extracted and screened for the relative abundance of trisaccharide to tetrasaccharide units (DP3:DP4 ratio), and four samples, representing the DP3:DP4 extremes from both, were selected for further tests. The β-glucans were dissolved at 37 °C at 1% (w/w) concentration, and the rheological properties were investigated after 2 h or 24 h storage. Lower DP3:DP4 ratios were seen in oat (1.8–1.9) than barley (2.4–2.8) β-glucans, and the results pointed to low variation among the studied Finnish cultivars. Dynamic oscillatory measurements indicated the formation of a gel-like structure in the oat β-glucans during the 24 h storage, while the barley β-glucans behaved as entangled polymer solutions, with little to no structure development. The results support the hypothesis that, following dissolution at 37 °C, a low DP3:DP4 ratio facilitates the gelation of β-glucan as it allows for sufficient opening of the structure while leaving undissolved regions that can act as nucleation sites for junction zone formation.