Propriedades reológicas do suco de buriti (Mauritia flexuosa)

Abstract

Knowing the rheological behavior of tropical fruit juices is very important for both consumers and food industry. This study investigated the rheological behavior of buriti (Mauritia flexuosa) juice. The rheological data were obtained through a rotational viscometer with concentric cylinder geometry (Brookfield, model DV II+). The assays were carried out at six different temperatures (10, 20, 30, 40, 50, and 60 °C) and the experimental results were adjusted through the Power Law and Mizrahi-Berk models. The buriti juice showed non-Newtonian behavior at the six temperatures. When quantifying apparent viscosity (hap), therheological parameters (K and n) were obtained by adjusting the Power Law, which was shown to be quite appropriate in predicting the juice’s rheological behavior, with determination coefficients r² > 0.99 for five out of the six temperatures investigated. The product showed pseudoplastic (n < 1) behavior and the flow behavior index decreased as temperature increased. The effect of temperature on apparent viscosity was described through an Arrhenius equation and discussed in terms of energy of activation (Ea) and the values of Ea ranged from 2.84 to 3.0 kcal/gmol for the strain rate used.