Effects of thermosonication on ascorbic acid, polyphenols and antioxidant activity in blackberry juice

Limited research studies exist that assess the impact of thermosonication (TS) processing on antioxidant compounds in blackberry juice. Different combinations of TS parameters (temperature, amplitude power and time) were applied to blackberry juice using a pilot-scale ultrasonic transducer (UIP500hdT). In low-temperature treatment, the juice was treated at 10 degrees C and 50% amplitude power for 5 min (10-50-5) showed the best retention of ascorbic acid (0.95 mg), total phenolic content (TPC) (459.55 mg GAE), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) (261.34 mg TE) and ferric reducing antioxidant power (FRAP) (604.09 mg TE). Similarly, in high-temperature treatment, the juices were treated at 70 degrees C and 100% amplitude power for 5 min (70-100-5) showed ascorbic acid (1.05 mg), TPC (166.17 mg GAE), DPPH (304.95 mg TE) and FRAP (686.93 mg TE). Both low- and high-temperature treatments showed higher retentions in these attributes than untreated and pasteurised juices. The results were further supported by high retention of predominant polyphenols, namely cyanidin-3-O-glucoside (400.58 and 336.94 mg/100 mL, for 10-50-5 and 70-100-5, respectively). A similar trend was observed in the contents of cyanidin-3-O-rutinoside, procyanidin dimer B-2, 5-chlorogenic acid, epicatechin and rutin. TS treatment in overall could be a considerable alternative option to be used for antioxidant-rich blackberry juice production as it has effects on phytochemicals similar to that of pasteurisation.

Automated summary

Limited research studies indicate that thermosonication (TS) processing has an impact on antioxidant compounds in blackberry juice. By adjusting the parameters of TS, such as temperature, amplitude power, and time, the retention of vitamin C, total phenolic content, DPPH, and FRAP in the juice can be improved. Both low-temperature and high-temperature treatments show higher retentions in these attributes compared to untreated and pasteurized juices. The retention of major polyphenols is also higher. Overall, TS treatment can be a viable alternative for producing antioxidant-rich blackberry juice, with effects on phytochemicals similar to pasteurization.