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Abstract
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We investigated the simultaneous effects of temperature, ultrasound, and vacuum pressure in the tomato juice concentration process. To this end, a novel ultrasound-thermal concentrator under vacuum conditions was fabricated. The process was performed at three levels of ultrasound power (48, 84, and 120 W), three vacuum pressures (10, 20, and 30 kPa), and three temperatures (50, 60, and 70 ◦C). Also, ultrasound effects were investigated using other experimental setups without ultrasound. We obtained the optimal conditions for the tomato juice concentration process through the ultrasound-thermal method with ultrasound power of 120 W, the vacuum pressure of 10 kPa, and at 64 ◦C also by the thermal method were obtained at 65.5 ◦C and a vacuum pressure of 10 kPa. Overall, applying ultrasound in tomato juice concentrating had positive effects such as reducing the concentration time (28.42%) and total energy consumption (4.94%), as well as increasing the lycopene (49.20%) and vitamin C contents (22.10%).
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