Cynthia Andriani: CONNECTING CASEIN MICELLE STRUCTURE WITH RHEOLOGY OF SKIM MILK CONCENTRATE (SMC)

<p dir="ltr">This study links skim milk concentrate (SMC) viscosity to the micro- and nanostructure of casein micelles, acknowledging their soft, deformable nature. Viscosity data for SMC prepared from vacuum-evaporated reconstituted skim milk powder were collected across temperatures (5-55 °C), casein concentrations (25–250 g/L), and shear rates (0.1–1000 1/s). Structural analyses employed multiple techniques—dynamic light scattering (DLS), Environmental SEM (E-SEM), cryo-SEM, TEM, cryo-TEM, and rheo-SAXS—to capture complementary information with inherent trade-offs. High concentration, high temperature, and low shear rate induced thickening, evidenced by hysteresis in conventional shear-rate sweeps; a modified viscosity method was developed to mitigate time-dependent effects. Results show viscosity varies with shear rate, concentration, temperature, and time. Applying the Maron-Pierce-Quemada model indicates a decrease in voluminosity with increasing temperature, protein concentration, and shear rate, consistent with micelle deformation and reduced hydration. Rheo-SAXS reveals anisotropy and prolate ellipsoid-like micelles, supported by cryo-SEM in concentrated suspensions.</p>