TEMPERATURE OF LIQUID CONTENTS IN RVA CANS DURING OPERATION

The Rapid Visco-Analyser (RVA) normally does not indicate the actual t emperature inside the sample can during operation, but rather that of the heated block. Sample cans were modified by incorporating a thermoc ouple that was immersed in the contents, and its temperature could the n be monitored during operation. Three different starch types and four temperature profiles of differing ramping rates were used. It was fou nd that the actual paste temperature lagged behind the block temperatu re, and the lag was a function of the heating/cooling rate and the app arent peak viscosity of the starch sample. A second-order multiple-reg ression equation (r = 0.94) was developed to predict that lag. The res ults can be used to predict the actual liquid temperature for any give n point on the pasting curve.