Rheological behavior of concentrated tucupi

Tucupi, which is widely enjoyed in the North region of Brazil, is a fermented liquid derived from cassava (Manihot esculenta Crantz) and has been taken abroad for its exotic characteristics. This study aimed to assess the theological behavior of tucupi with 30, 35, and 40% solids and concentrated at 50, 70, and 90 degrees C. The theological data were obtained at 25, 40, 60, and 80 degrees C with increasing and decreasing shear rates. Rheology at 25 degrees C indicated that the partial gelification of starch during concentration causes a decrease in the product's viscosity and, if the concentration is carried out at a temperature that favors total starch gelification, the product's viscosity increases. Concentrated tucupi behaved as a pseudoplastic fluid, but at 60 and 80 degrees C with increasing shear rates, the product behaved as a dilatant fluid. Hysteresis were observed in flow curves starting at 40 degrees C, which characterizes concentrated tucupi as a rheopectic fluid. The Ostwald-de Waele model predicted the product's flow curves and an Arrhenius-like equation described the dependence of temperature on apparent viscosity for the rheological data obtained with increasing shear rates. The product's activation energy (E-a) values ranged from 16.86 to 25.23 kJ/mol as a function of concentration.