Kinetic model of freeze concentration of orange juice

In order to decrease the juice loss during freeze concentration progress of ice crystals and improve the concentration speed, it’s essential to obtain the growth law of ice crystals. Orange juice was concentrated from originally 13 to 34 Bx by two-stage freeze concentration which was based on the solid-liquid phase equilibrium. The relationship between orange juice concentration and its freezing temperature was investigated. Experimental results showed there was linear correlation between freezing temperature and concentration. And the freezing point decreased with concentration increasing. It was also researched the connection between soluble solids and concentration of orange juice. The obtained distribution coefficient K indicated that soluble solids in crystals increased with juice concentration raise. According to Fick diffusion equation, The kinetic model of ice crystals growth was developed, which showed that the growth rate of ice was proportional to the mass of ice and was inhibited by the maximal mass of ice. Powell method was adopted to search the parameters of the model and it’s solution was obtained with numerical integrition using Runge-Kutta method. The results obtained from the kinetic model were coincident with that of experiments. The established model can provide theoretical basis and reference on equilibrium of heat transfer and ice crystals growth and be helpful to understand the mechanism of freeze concentration of orange juice.