Reologia de polpas de caju (Anacardium occidentale L.) e goiaba (Psidium guajava L.).

Abstract

In this experimental work the behavior rheological of the guava pulps, separated cashew was determined and combined in the proportions of 80%goiaba20%caju, 20%goiaba80%caju, 60%goiaba40%caju, 40%goiaba60%caju, 50%goiaba50%caju being elaborated starting from three types of pulps: integral, sifted and centrifuged. All the samples were analyzed in the temperatures of 10°C, 20°C, 30°C, 40°C, 50°C and 60°C with use of the redmetro Haake Rolovisco, system of plates parallel pQ 45. The experimental data were adjusted through the models rheological o f Ostwaf-of-Waelle (Law of the Potency), Casson, 1 lerschel-Bulkley and Mizrahi-Berk. The model of Mizrahi-Berk described all the samples appropriately, except for 50%goiaba50%caju centrifuged, where the best model was of I lerschel-Bulkley. The suspended solids and the temperature influenced the apparent viscosities and the pattern of behavior rheological o f the samples. The samples presented behavior no-newtoniano with characteristic pseudoplasticas, with exceptions for some cases o f the combinations 50%goiaba50%caju, where behavior dilatante was observed. The dependence of the apparent viscosity, to a rate of fixed deformation, with the temperature, it was described by an equation of the type Arrhenius (n = n0*exp(Ea/RT). it was observed that the values of activation energy were larger for the centrifuged samples, with values between 1,38 Kcal/gmol and 2,36 Kcal/gmol.