Relationship between the thermal conductivity and rheological behavior of acerola pulp: Effect of concentration and temperature

Abstract

This study aimed to evaluate the thermal conductivity and rheological behavior of acerola pulp at concentrations of 5.5, 7.5, 9.5, 11.5 and 13.5 °Brix and temperatures of 20, 30, 40, 50 and 60 °C. Among the models used to determine conductivity, Maxwell-Eucken was used for data acquisition. Linear equations were fitted to evaluate the influences of concentration and temperature on the thermal conductivity of the pulp. The pulp structure, particle sizes and relation between insoluble and soluble solids were also discussed. The rheological behavior, specifically apparent viscosity versus shear rate, was influenced by both the soluble solids content and the temperature. Among the mathematical models used to test the fit of the experimental data, the Herschel–Bulkley model provided the best statistical adjustments and was then used to determine the rheological parameters. Apparent viscosity was correlated with temperature by the Arrhenius equation. Acerola pulps were shear thinning and thermal conductivity increases with viscosity decreasing with increasing temperature. The structures and concentrations had an impact upon the effective thermal conductivity. The temperature and concentration values have been fixed and equation expressing conductivity as a function of apparent viscosity was proposed, which enable the evaluation of an existing relationship between the two properties.