Modification of Bostwick method to determine tomato concentrate consistency

Evaluation of the consistency of tomato concentrate with different °Bx showed that the error in consistency measurement of tomato concentrate by Bostwick method was aroused especially at high °Bx. The studies indicated that the drying rate of insoluble solids and the lacking of reconstituting properties of them caused error. In this research the effect of variety, concentration and the temperature of consistency measurement were evaluated to determine variation of error in Bostwick consistometer and to modify it. The results showed that variety had no effect on the accuracy of consistency measurement by Bostwick method, but concentration and temperature had a highly significant effect on the accuracy of this assay and thus the error of Bostwick consistometer increased, especially at high °Bx. Also heating of diluted tomato concentrate (up to 45 °C) and then cooling it could decrease the error of consistency measurement considerably. Consistency can also be estimated accurately by using the Correlation between °Bx, temperature and Bostwick consistency (R2 = 0.94).