Pressure gradients application for accelerating corn hydration

Abstract

Three varieties of corn kernels were hydrated under pressure gradients in the range of 1540 to 1580 cm Hg, and at atmospheric pressure for comparison. Hydration at atmospheric pressure was modeled by the first order kinetics model and by the Fick’s second law of diffusion. Rate constants of 0.192, 0.184 and 0.141 h-1, and water effective diffusivity of 5.4 ×10-11, 3.6 ×10-11, and 1.9 ×10-11 m2 s-1 were obtained for blue, yellow and white corn kernel, respectively. Significant polynomial equations described the corn kernels hydration under pressure gradients, as a function of vacuum pressure, vacuum time and hydration time. Hydration rates of the studied grains were significantly enhanced using the pressure gradients, compared to the conventional method. Pressure gradient soaking required 60% less time than the conventional soaking, to reach a water content of 45% in corn kernels. The hydration extent of corn kernels determined the levels of solutes leaching, in both soaking treatments. Minimum hydration levels for initiating leaching of soluble solids were observed.