Comparison of thermo-sonication and conventional pasteurization on the quality attributes of some selected citrus fruit juices

• Thermo-sonication of juice from different indigenous citrus varieties. • Physico-chemical, microbial counts and antioxidant activity evaluations of treated juices during storage. • Antioxidant activity also significantly increased in thermo-sonicated and sonicated juices. • Among all treatments, the highest decrease in total plate counts was observed in thermo-sonicated (T 4 ) treated samples. • citrus juices might be processed more safely with improved quality by using thermo-sonication approach. The current study focused the comparison of thermo-sonication and conventional pasteurization on the quality characteristics of different citrus fruit juices during storage. Among citrus fruit varieties, Red Blush is considered superior in terms of its average fruit diameter, weight, and segment counts. The highest values of acidity were observed in untreated Shamber juice T 0 (0.209 %) whereas the lowest values were found in the pasteurized juice T 1 (0.114 %). Pasteurization resulted in decreased acidity levels. Regarding microbiological quality of treated juices, it was found that total plate counts significantly decreased in thermo-sonicated (T 4 ) and chemically preserved and pasteurized (T 3 ) juices compared to sonicated (T 5 ) and untreated (T 1 and T 2 ) juices. The least reduction in total plate counts was observed in Shamber juice, while the maximum reduction occurred in Blood Red juice during storage. The highest TP contents were observed in T 4 (432.11±21.60 µg GAE/mL) and T 5 (450.32±36.03 µg GAE/mL) of Shamber juice. Regarding TF contents, the highest values were found in T 4 (420.58±29.44 mg CE/100 mL) and T 5 (435.32±17.41 mg CE/100 mL) of Red Blush juice. The maximum DPPH radical scavenging activity was observed in T 4 (752.11±60.16 μg AAE (ascorbic acid equivalent)/mL) and T 5 (696.90±34.84 μg AAE/mL) of Blood Red juice. Similar trend in DPPH free radical scavenging activity was observed in the juices of other citrus varieties. It was observed that thermosonication treatment (T 4 ) showed higher DPPH radical scavenging activity as compared to ultrasonic treatment (T 5 ). It may be concluded that thermosonication had positive influence on the antioxidant potential and negative impact on increase in microbial load.