Modelling the wetting and cooking of a single cereal grain

Three models are presented for the wetting of whole grains of cereal. Two are for temperatures below gelatinization temperatures, one of which incorporates the effects of swelling of the grain. A third model is presented for wetting of a grain at temperatures above gelatinization, and hence cooking the grain. The models are developed as partial differential equations, and solved in a variety of ways. A model that ignores swelling at temperatures below gelatinization is solved for wetting times by using the concept of mean action time, which reduces the problem to an exactly solvable linear Poisson equation. The other two models, which include swelling and cooking respectively, are solved approximately, taking advantage of the steep nonlinear diffusion fronts that develop. The aim of the modelling is to improve understanding of the cooking of whole-grain cereals prior to processing into breakfast cereals. Moisture penetration curves are obtained and compared. Regions where the penetration rate is approximately linear are noted, suggesting that nonlinear diffusion equations are a promising way to model grain wetting and cooking.