Normalized Weibull distribution for modeling rehydration of food particulates

Dehydrated food particulates have a rapidly growing market, and their reconstitution is essential in meeting consumers' expectations. Optimal reconstitution properties can be achieved by controlling the drying process and the rehydration conditions. Fundamentals of transport phenomena, particularly diffusion, external resistance and relaxation are some of the mechanisms governing water uptake during rehydration. The Weibull distribution is applied in many biological systems, and was found valuable in the modeling of the rehydration process. Simulation and experimental data showed that the traditional Weibull distribution should be normalized to account for product geometry, thickness and final water content. The Weibull β-shape parameter varied with geometry and the mechanism of water uptake. The derived values for spheres, cylinders and slabs were for diffusion: 0.67, 0.72 and 0.81 respectively; for internal resistance: 1.00, 0.98 and 0.97 respectively; and for relaxation: 1.21, 1.32 and 1.60 respectively. The Weibull distribution provides an insight into the rehydration phenomena that govern water uptake by foods containing particulates during rehydration, and could be used for differentiating between diffusion, external resistance and relaxation processes.