The aim of this work was to study and to model the effects of time-temperature conditions for sterilization on the overall quality of tomato puree. Tomato puree was produced from raw tomatoes in a pilot plant. Three sterilization tests were carried out at 90, 95 and 100 degreesC to obtain kinetic constants of quality properties. Heat and oxidative damage was observed in samples throughout sterilization. The furosine content increased, both the ascorbic acid content and the antioxidant activity of the hydrophilic fraction decreased, and a variation in colour (DeltaE) occurred. No significant variations were found in the lycopene content, antioxidant activity of lipophilic fraction and sensory descriptors. Data were processed to obtain the relevant reaction kinetic constants, and a mathematical model was set up, which was able to predict quality variations in tomato puree during sterilization both under isothermal and non-isothermal conditions. The model was applied as a chart for optimization of sterilization. (C) 2002 Elsevier Science Ltd. All rights reserved.