Effect of Thermal Concentration on the Physico-chemical Properties and Color Characteristics of Sour Orange Extract

Citrus-based drinks are one of the most popular fruit drinks. Juice and paste are high consumption products of sour orange. In the present study, viscosity, specific heat capacity, heat transfer coefficient, density, dry mass matter, pH, electrical conductivity, total dissolved solids, and color characteristics of sour orange extract were investigated during different steps of thermal concentration. Arrhenius and Modified Arrhenius models were also investigated to describe the relationship between viscosity and temperature. By decreasing the ratio of secondary volume of extract to primary volume of juice from 100% to 15%, the values of density, dry mass matter, and pH increased from 1035 to 1340 kg.m^-3, increasing from 6.89% to 47.45% and decreased from 2.09 to 1.38, respectively. Also, specific heat capacity and heat transfer coefficient decreased from 4146 to 2984 J.kg^-1.K^-1 and decreased from 0.584 to 0.402 W.m^-2.K^-1, respectively.

Keywords: viscosity, specific heat, heat transfer coefficient, electrical conductivity, image processing