Linking specific energy input to microstructure and rheology in microfluidized citrus fibre cellulose microfibril dispersions

This study aims to establish a quantitative link between specific energy input during microfluidization and the resulting microstructure and rheology of citrus-fibre-derived cellulose microfibril dispersions. Dispersions containing 0.5 wt%, 1.0 wt% and 1.5 wt% citrus fibre were microfluidized across a range of processing intensities, after which their network structure was visualized by confocal laser scanning microscopy and their viscoelastic behaviour was evaluated by oscillatory rheology. Specific energy input, expressed as the pressure derived energy supplied per unit mass of fibre, was introduced as a processing parameter and was found to govern both microstructure and rheology. Confocal laser scanning microscopy revealed a heterogeneous network composed of flocs of cellulose microfibrils, separated by microfibril-poor void regions forming the continuous phase. Increasing the specific energy input reorganized this architecture, altering both the floc volume fraction and the spatial homogeneity of the network. The storage modulus G ′ showed a clear non-monotonic dependence on specific energy input, with moderate inputs strengthening the network and higher inputs reducing its elasticity. Across all concentrations, G ′ scaled with bulk fibre concentration according to a power law, while the scaling of the floc elasticity with the microfibril concentration inside the flocs remained constant. Using the invariant intra-floc exponent to scale G ′ by the bulk fibre concentration collapsed all measurements onto a single master curve governed by specific energy input, revealing two regimes separated by a threshold, establish a quantitative processing–structure–property framework for microfluidized citrus-fibre networks. • Specific energy input governs microstructure of citrus fibre derived CMF dispersion • Storage modulus shows a non-monotonic response to increasing specific energy input • Bulk elasticity scales with concentration, while floc-level mechanics stay constant • A single master curve emerges when normalizing by the intra-floc exponent