Abstract: The distribution of water in different states and the characteristics of the water states are crucial for food materials. As the result of interactions between water and the solid matrices, isothermal water adsorption inevitably reflects the energy state of adsorbed water. The Caurie and Henderson models, which are often used in food research, together with four composite isothermal adsorption models were applied to model the water desorption of glutinous rice flour. The results were used to elaborate the practicability and limitation of characterizing the states of adsorbed water based on isothermal adsorption models. Composite isothermal adsorption models made it possible to understand the distribution of water in different states and its evolution with water activity from the water adsorption data. Fitting performance evaluation was not enough to identify the most suitable composite model. Additional confirmation by other techniques were necessary in some cases. Judging whether the unique assumption of a model was satisfied or not was a feasible strategy for identifying the most suitable model for food materials.

Key words: water state, isothermal adsorption, interaction, feasibility, glutinous rice flour