This study evaluates the effects of high pressure microfluidization of ketchup mixes on the physical properties and lycopene content. During the processing the pressure level ranged between 200 and 2000 bar, while the number of passes was kept constant. When the treatment pressure was increased from 200 to 1200 bar, the yield stress, elastic modulus, storage modulus. and Bostwick consistency values of the ketchup samples improved. However, over-processing was observed for the samples treated at 1600 and 2000 bar. Light and scanning electron microscope images were used as visual means to observe microfluidization induced structural changes. Colloidal stability measurement showed that increasing microfluidization pressure improved physical stability of the samples. Reducing the size and changing the nature of tomato solids through high pressure microfluidization also increased the detectable lycopene levels of the ketchup samples. (C) 2011 Elsevier Ltd. All rights reserved.