The colour change (yellowing or reddening) that occurs during parboiling affects the consumer acceptance of parboiled rice. In order to understand the factors controlling colour change in rice during hydration, trials were performed that examined the effect of variety (four commercial varieties: Kyeema, Langi, Reiziq(P) and Sherpa(P)), milling properties (Sherpa(P) High Head Rice Yield and Sherpa(P) Low Head Rice Yield), degree of processing before hydration (paddy, brown rice, milled rice) and hydration temperature (below and above gelatinisation temperature: 60 degrees C and 90 degrees C respectively). The total colour difference (Delta E-00) was calculated and four different models (zero order, first order, fractional and Page) were evaluated in order to predict the Delta E-00. The Page model was found to be the best model for predicting Delta E-00. There was no difference in Delta E-00 between the breakage resistant and breakage prone grains however the varietal effect was observed. The degree of processing of rice before hydration affected the total colour change where the brown rice had the highest Delta E-00 followed by paddy and milled rice. (C) 2015 Elsevier Ltd. All rights reserved.