Weight loss of unpackaged foods during freezing and later storage is an important quality and economic issue. It is originated on surface ice sublimation due to differences in water activity between food surface and the refrigerating air. Weight loss rate is determined by refrigerating conditions and product characteristics. The modelling of this phenomenon has merited very little attention; at present there are no simplified methods to predict weight losses during the freezing and the storage of unpackaged foods. In previous studies we developed a detailed model for. the simultaneous heat and mass transfer during food freezing and storage with ice sublimation. Based on the information of this numerical model, simplified analytical methods for the prediction of weight loss during the freezing and the storage of unpackaged frozen foods were developed. The methods account for product characteristics and storage conditions. The prediction equations are very simple and results of their use-simulating usual freezing and storage conditions for different products-give very good accuracy when tested against the previously cited numerical model and experimental data. (C) 2004 Published by Elsevier Ltd.