Flow induced fibre alignment in Mycoprotein paste

Abstract The effects of extrusion and squeeze flow processing on the microstructure of Mycoprotein filamentous paste, a novel meat product alternative, are investigated. The flow induced effects are quantified in terms of fibre orientation measured by a technique of fluorescence microscopy and image analysis. Imaging of the original mycelia fibre paste showed that its microstructure is ‘isotropic’. Squeezing of the native paste does not result in any significant fibre rearrangement. This is attributed to the high fibre concentration and, thus, high level of fibre entanglement in the squeezed film, and slip at the wall. A semi-concentrated suspension of mycelia fibres in a golden syrup matrix, however, shows considerable structural rearrangement throughout. Extrusion of the native paste leads to a high degree of fibre alignment in the direction of flow with a high proportion of the fibre population (∼80–90%) being realigned. An Exponential-Uniform Mix distribution was successfully used to describe fibre orientation in both extrusion and squeeze flow. The results show the strong link between the microstructure of highly structured food products and the mode of processing used. They may also have important implications for the rheological testing of such structurally complex materials, as the rheological response of the material may well dependent on the way it is made to interact with the instrument.