Revista Brasileira de Fruticultura
On-line version ISSN 1806-9967
FERREIRA, Gilvanete Maria; GUIMARAES, Maria José de Oliveira Cavalcanti and MAIA, Maria Cristina Antun. Effect of temperature and shear rate in the properties of whole flow Cupuassu pulp (Theobroma grandiflorum). Rev. Bras. Frutic. [online]. 2008, vol.30, n.2, pp. 385-389. ISSN 1806-9967. http://dx.doi.org/10.1590/S0100-29452008000200020.
The rheological behavior of the entire cupuassu pulp was determined in the temperature range 10 - 60ºC. The effects of temperature and deformation rate were evaluated by means of shear flow tests. Rheometry analyses were conducted with a Thermo Haake RheoStress 1 system. Rheograms were described by models by Ostwald-of-Waelle and Herschel-Bulkley. The Ostwald-of-Waelle model successfully represented pulp flow behavior. The product presented shear-thinning behavior and the flow behavior index (n) decreased with the increase of temperature. The effect of temperature on the apparent viscosity in cupuassu pulp was described by an Arrhenius equation and discussed in terms of activation energy. The increase in shear rate caused an energy increase, and values were obtained in the range of a line from 1 to 2 kcal/gmol.
Keywords : cupuassu; rheology; shear flow; Arrhenius.