This study aims to determine the stability improving effects of size-reduced dietary fibers in food emulsions. Orange zest fiber and corn fiber were microfluidized under high pressure (up to 15,000psi). Model emulsions were prepared by adding 1, 2 and 3% of the fibers into the mixture of 3% whey protein isolate and 20 and 50% oil. These mixtures were homogenized through both colloid mill and microfluidizer to form model emulsions. Rheological properties such as flow and oscillation were measured with frequency scanning rheometer, and emulsion stabilities were measured with dispersion analyzer. Increase in oil amount increased emulsion stabilities independent from fiber content. Likewise, ascending fiber amount also improved stabilities. At constant oil level, 3% fiber containing emulsions had higher elastic and viscous moduli (G' and G'') and viscosity values than those of other groups in same material. In general, addition of dietary fiber into model food emulsions improved stability properties. © 2014 Wiley Periodicals, Inc.