Evaluation of processing condition on physicochemical properties and flow behavior of sour orange juice concentrate

In this research, sour orange juice concentrate was produced using a vacuum evaporator at pressure of 55 mm Hg and evaporation temperatures of 50- 80 °C. Rheological properties of the sour orange concentrates were evaluated under different conditions of total soluble solid (30-50 °B) and temperature (5-55 °C) at shear rate range of 0-160 s-1. Viscosity of sour orange concentrates decreased with shear rate and a non-Newtonian behavior was observed. Consistency index decreased with temperature and increased with total soluble solid. Moreover, vitamin C content of the samples before and after evaporation at 50 or 80 C was determined using HPLC. The results indicated that with increasing evaporation temperature the vitamin C loss increased (P<0.05). The lightness of the concentrates was evaluated as a function of evaporation temperature and final concentration. The results showed that the lightness of sour orange concentrate was affected by temperature and time of concentration (P<0.05). However, the sour orange drink prepared from the samples concentrate at 70°C and fresh sour orange was evaluated to be better in the case of flavor and taste, sensory evaluation of the sour orange drinks prepared from the concentrate or fresh sour orange juice did not show any significant differences.