Características químicas, reológicas e termofísicas de polpas de bacuri.

Abstract

The present work had as objective to determine some chemical characteristics (insoluble solids, humidity, ashes, total solids, vitamin C, pH, total, acidity), Theological behavior and termophysical properties (specific heat, specific mass, diffusivity and thermal conductivity) of the pulp of the bacuri (Platonia insignis Mart.) in concentrations of 5,7,5, 10, 12,5, 15, 17,5, 20°B. For the determination reological, in triplicata were used the temperatures of 10, 20, 30 40 50 and 60°C, with the use of the viscosimeter Brookfield, model RVT, with geometry of concentric cylinder. The experimental values were used to adjusted to the models of the Potency Law or Ostwald-of-Waele, Herschel-Bulkley and Mizrahi Berk, where the best adjusted model of Herschel-Bulkley was described. All samples presented behavior non - newtoniano. For the termophysical properties the specific heat, was obtained using the mixture calorimeter, with a value between the smallest and larger concentration from 3.616 to 2.986 kJ/kg°C, observing with this, a decrease in the increase of the concentration; with relationship to the values of the specific mass, was certain through the pycnometers of 25 ml, for temperatures of 25 and 30°C, in sextuplicate, varying 1009.948 respectively to 1048.358 kg/m3 and 1008.399 and 1044.438 Kg/m3, observing an increase according to the temperature increment, for the obtaining of the diffusivity, the methodology of was used DICKERSON (1965), and observed values reduce with the increase of the concentration, accordingly, 5°B, 1.787 x 10 "7 to 20°B 1.637 x 10"7; the thermal conductivity was calculated above through the determinations termophysical above-mentioned and it also reduced accordingly the increase of concentration 5°B 0.643 to 20°B 0.500 (W/m°C).