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

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 T₀ (0.209 %) whereas the lowest values were found in the pasteurized juice T₁ (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 (T₄) and chemically preserved and pasteurized (T₃) juices compared to sonicated (T₅) and untreated (T₁ and T₂) 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 T₄ (432.11±21.60 µg GAE/mL) and T₅ (450.32±36.03 µg GAE/mL) of Shamber juice. Regarding TF contents, the highest values were found in T₄ (420.58±29.44 mg CE/100 mL) and T₅ (435.32±17.41 mg CE/100 mL) of Red Blush juice. The maximum DPPH radical scavenging activity was observed in T₄ (752.11±60.16 μg AAE (ascorbic acid equivalent)/mL) and T₅ (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 (T₄) showed higher DPPH radical scavenging activity as compared to ultrasonic treatment (T₅). It may be concluded that thermosonication had positive influence on the antioxidant potential and negative impact on increase in microbial load.