A computer vision method was developed to determine the colour change of cheese during heating. The browning properties of both Cheddar and Mozzarella cheeses were analysed and compared. The influence of baking temperature (70-200 degreesC) and time (0-20 min) on the browning property of cheese was significant for both cheeses. However, the time and temperature dependencies of a specially defined browning factor (BF) were different for Cheddar and Mozzarella cheeses. Cooking for 2-4 min, the BF of Mozzarella cheese increased almost linearly with baking temperature. As for the Cheddar cheese, after heating for 8-12 min, a linear relationship between the BF and baking temperature was observed from 70 to 130 degreesC. Further browning hardly occurred when cooking temperature increased from 130 to 160 degreesC, probably because of depletion of reducing sugars and amino groups in cheese that are necessary for the browning reaction. When heating at temperatures above 160 degreesC, the colour of Cheddar cheese darkened dramatically due to scorching. The results also show that the computer vision method developed provides an objective and efficient approach for assessing the browning of cheese. (C) 2002 Elsevier Science Ltd. All rights reserved.