In this study, for the first time, the function of acid-activated sepiolite clay was evaluated for clarification of pomegranate juice. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. After that, under optimal condition, efficiency of sepiolite, bentonite and combination of these fining agents with gelatin and kieselgel was compared for clarifying pomegranate juice. The results showed that the best conditions for juice clarification were 0.05% (w/v) clay concentration, temperature of 50 °C and time of 2 h. The results revealed that treatments of bentonite–gelatin–kieselgel and sepiolite–gelatin–kieselgel were the most active fining agents that their use led to a reduction of 99.7% in turbidity of pomegranate juice. Kinetic study for different features was performed, and the results indicated that rate of changes in turbidity, viscosity, total phenolic contents and colour with time followed first-, first-, zero- and zero-order kinetic models, respectively.
Sepiolite was firstly activated using a strong acid. The optimum conditions of clarification process were achieved using response surface methodology based on juice turbidity as a response. The function of acid-activated sepiolite clay was evaluated and compared with commercial clarifying agents for clarification of pomegranate juice in respect to the values of TPC, color, viscosity and turbidity.