اصلاح روش اندازه گيري قوام رب گوجه فرنگي به روش بوستويك

Modification of Bostwich method to determine tomato concentrate consistency

Tomato concentrated products were dilluted up to 12 percent solids to measure their consistency by Bostwick consistometer. The evaluation of the consistency of tomato concentrated with different Brixes showed that the error in consistency measurement of tomato concentrated by Bostwich method increased as the Brix increased. The studies indicated that the drying rate of insoluble solids and the lacking of reconstituting properties of them were caused error in the measurement of paste consistancy (especially at high Brixes). In this research. the effect of variety, tomato concentrated Brix and the temperature of consistancy measurement were evaluated to determine the error changes in Bostwich consistometer and to modify it. The results showed that the variety had no effect on the accuracy of consistency measurement by Bostwich method, but Brix and temperature had a very significant effect on the accuracy of this assay and thus the error of Bostwick consistometer increased, especially at high Brixes. It was concludedthat heating of dilluted tomato concentrated (up to 45 C°) and then cooling it can decrease the error of consistency measurement considerably. Also, the consistancy can be estimated accurately by using the regration between Brix, temperature and Bostwick consistency (R^2= 0.94).