The objective of this research was to determine the effect of ultrasound treatment on bioactive compounds (including total phenolic, total flavonoids, total carotenoids, ascorbic acid) of carrot juice in comparison with conventional thermal process. Carrot juice samples
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The objective of this research was to determine the effect of ultrasound treatment on bioactive compounds (including total phenolic, total flavonoids, total carotenoids, ascorbic acid) of carrot juice in comparison with conventional thermal process. Carrot juice samples were sonicated according to D-optimal response surface design with processing variables of temperature (25, 37.5 and 50°C), time (10, 20 and 30 min) and power (350 and 400 w) at a constant frequency of 24 kHz. Results showed that ultrasound temperature (P<0.01), time (P<0.01) and power (P<0.05) significantly decreased the ascorbic acid content of carrot juice samples. Ascorbic acid contents in heat-treated and sonicated samples reveled that sonication process had more protective effect of ascorbic acid. Ultrasound temperature significantly (P<0.05) increased the total carotenoid contents of the sonicated samples. On the other hand, ultrasound duration significantly (P<0.01) decreased the total phenolic contents of the sonicated samples; nevertheless, no significant difference was observed between sonicated and heat-treated as well as control groups. Total flavonoids content of the sonicated samples was significantly (P<0.01) decreased in comparison with the heat-treated and control samples. It was concluded that ultrasound treatment as a non-thermal preservation technique, leads to better retention of bioactive compounds (especially ascorbic acid, total carotenoids and total phenolic contents) compared to thermal process.
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