<p>This study aims to determine the rate of shrinkage of peas that occurs during the drying process. The pea samples were dried in a fluidized bed dryer. The shrinking rate is estimated via a nonlinear estimator constructed based on a numerical solution to the diffusion equation. The drying kinetics is the information fed to the algorithm. After comparing the estimated and experimental shrinking rates, it can be concluded that the implemented algorithm gives acceptable predictions of the shrinking rate. The experimental and estimated shrinking curves are compared with those that should be obtained if the shrinking process were ideal. From this comparison, it is concluded that the shrinking of peas is non-ideal. In addition, the volume shrinkage is modelled by the logistic equation.</p>