The effect of extrusion on the functional properties of oat fibre

Abstract

Extrusion is an effective method for the production of healthier snack foods, such as oat fibre products. The effect of this process on the physicochemical properties of oat fibre preparations containing high levels of β-glucan, however, has not been fully addressed. Oat fibre containing 28 g/100 g β-glucan was extruded using two levels of feed moisture (50 g/100 g or 60 g/100 g of feed materials) and two screw speeds (200 rpm or 300 rpm) at a constant barrel temperature profile (80 °C, 90 °C, 100 °C, 110 °C). A higher specific mechanical energy applied during extrusion correlated with an increase in specific surface area, greater sorption of water vapour and higher sorption energy for the monolayer of water associated with the surface of extruded products. The pasting properties of oat fibre were largely retained and the extent of molecular fragmentation was small, as the molecular weight of the soluble fraction, total soluble solids and water absorption index were not significantly altered. These data demonstrate that extrusion under these conditions can be applied to oat fibre preparations with high β-glucan content, resulting in oat products that retain their functional properties and potential health benefits.