NEW VISCOGRAPH FOR RHEOLOGICAL ANALYSIS OF A SMALL QUANTITY OF WHEAT-FLOUR

A cone-plate viscometer was developed to analyze viscosity changes dur ing heating of a small quantity of wheat flour suspension. The instrum ent consists of a cone, a plate, a temperature-control heater, and a w ater trap to prevent water evaporation from a sample. With this appara tus it its possible to record a viscogram using a only approximate to 100 mg of wheat flour. Although the flour concentration was low, the t emperature at which the viscosity began to rise in this cone-plate vis cometer was closer to the gelatinization temperature determined by dif ferential scanning calorimetry than that determined with other viscogr aphs. It suggests that the new apparatus was more sensitive to initial swelling of gelatinized starch. The maximum viscosity in viscograms o f wheat starch measured by the new instrument decreased with the alpha -amylase activity. Depending on the heating rate, viscogram parameters obtained with this instrument were well correlated with those obtaine d with other viscometers.