Shear disruption of soya protein precipitate particles and the effect of aging in a stirred tank

Abstract

An improvement in the resistance of isoelectric soya protein precipitate to capillary shear disruption was achieved by aging in a stirred tank. The aggregate strength was found to depend on the extent and duration of agitation prior to exposure to shear. An optimum value of an aging parameter Gt ∼ 10⁵ was determined, where G is the rms velocity gradient in the aging vessel and tis the time of aging. The disruption of precipitate aggregates by exposure to high rates of shear for short times was dependent on the rate of shear and time of exposure. The dominant mechanism of aggregate breakup was fragmentation, with erosion occurring to a lesser extent. The size of the fragments produced by shear disruption was weakly dependent on the rate of shear, with higher rates of shear producing smaller fragments.