Wet grinding and microfluidization of wheat bran preparations: Improvement of dispersion stability by structural disintegration

The enrichment of liquid food matrix with wheat bran has not yet been explored. This study investigated the impact of disintegrating wheat bran preparations on their stability at high moisture content. Three wheat bran preparations - standard bran, peeled bran and aleurone rich fraction - were modified by dry grinding, enzymatic degradation, wet grinding and microfluidization. The sedimentation of processed preparations was evaluated in water solution and related to their physical structure, solubilized compounds and suspension viscosity. In dry ground preparations mixed in water (5% w/w), most of the particles sedimented already in 5 min. Wet grinding disintegrated the physical structure of bran preparations (d50 = 10-16 µm), causing improvement of particle stability due to reduction of gravitational sedimentation. Enzymatic treatment with xylanase efficiently increased the total solubility of the bran preparations (from 18-24% to 40-50%), but the higher solubility was not related to the better stability of particles. Microfluidization of peeled bran and aleurone increased the viscosity and stability of dispersions. The higher viscosity of the microfluidized dispersions was likely correlated with the better homogenisation of the particles, and also with the modified microstructure of treated bran preparations. Disintegrated wheat bran preparations showed high potential for beverage applications.