Evaluation of methods used to measure tomato serum juice and paste consistency

The viscosity or consistency of tomato juice and paste is a major quality factor of these products. Yet the measurement methods have largely been empirical. For paste samples, the common method used is the Bostwick method, which works best for samples, which are adjusted to 12 degrees brix. This method does not work well for juice samples, which have brix readings below 12 degrees. For juices a common method is to separate the serum from pulp and measure serum viscosity with a capillary viscometer. The first objective of this study was to evaluate the used of a rotational rheometer for the viscosity measurement of tomato serums. The second objective was the evaluation of the helical screw rheometer for paste consistency measurements as an alternative to Bostwick method.