Ultrasonics, which has been regarded as a rapid and non-destructive tool, has been used to investigate the rheological properties of syrups. In the present work, the effect of gelatin, sugar and citric acid levels on the rheological properties of gel and syrups was studied. Gels and syrups containing various concentrations of gelatin (4, 6, 8 g), sugar (5, 10, 15 g) and citric acid (0.25, 0.50, 0.75 g) were prepared and evaluated. Gel properties such as gel strength and relaxation force were measured using an Instron Universal Testing Machine. Syrup properties such as ultrasonic velocity and compressibility were determined using a multifrequency ultrasonic interferometer. The regression models were also computed for gel and syrup properties as a function of gelatin, sugar and citric acid levels. Gel strength was observed to be significantly affected by gelatin and citric acid. Ultrasonic velocity was observed to be mainly dependent on sugar and gelatin concentrations while compressibility was mainly dependent upon sugar level. The regression models developed could be used as a tool to manipulate rheological properties as a function of gelatin, sugar and citric acid level. (c) 2004 Elsevier Ltd. All rights reserved.