Rheological and thermophysical properties of blackberry juice

Food Science and Technology (Campinas)

Renato Alexandre Ferreira Cabral²  Carlos Eduardo Orrego-alzate¹  Ana Lúcia Gabas¹  Javier Telis-romero² 

[1] ,Universidade Estadual Paulista Departamento de Engenharia e Tecnologia de Alimentos São José do Rio Preto SP ,Brasil

关键词: fruit juice;    rheology;    thermal conductivity;    thermal properties;    condutividade térmica;    propriedades térmicas;    reologia;    suco de fruta;   

DOI  :  10.1590/S0101-20612007000300025

来源: SciELO

【 摘 要 】

Rheological and thermophysical properties were determined for blackberry juice, which was produced from blackberry fruit at 9.1 ± 0.5 °Brix and density of 1.0334 ± 0.0043 g cm-3. The concentration process was performed using a roto evaporator, under vacuum, to obtain concentrated juice at about 60 °Brix. In order to obtain different concentrations, concentrated juice was diluted with distilled water. Rheological measurements were carried out using a Rheotest 2.1 Searle type rheometer. In the tested ranges, the samples behaved as pseudoplastic fluids, and the Power-Law model was satisfactorily fitted to the experimental data. The friction factor was measured for blackberry juice in laminar flow conditions of pseudoplastic behavior. Thermal conductivity, thermal diffusivity and density of blackberry juice at 9.4 to 58.4 °Brix were determined, in triplicate, at 0.5 to 80.8 °C. Polynomial regression was performed to fit experimental data obtaining a good fit. Both temperature and concentration showed a strong influence on thermophysical properties of blackberry juice. Calculated apparent specific heat values varied from 2.416 to 4.300 kJ.kg-1 °C in the studied interval.

【 授权许可】

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