Effect of thermo-sonication on the physicochemical properties, bioactive compounds, micronutrients, and antioxidant activity of cranberry juice

Fruits such as cranberry (Vaccinium macrocarpon Aiton), that contain several phenolic substances, are processed commercially as juices, requiring treatments to extend shelf-life. Thermo-sonication, the synergistic application of mild heat and ultrasound, is a promising non-thermal liquid foods processing technology. This study examined the kinetics of change of physicochemical properties, micronutrients, key bioactive compounds, and color attributes of thermo-sonicated cranberry juice at three varying temperatures 35 °C, 45 °C, and 55 °C, over varying treatment times of 1, 3, 5, and 7 min in comparison to ultrasonication treatment alone at same time durations. The total carotenoids, total soluble solids (TSS), pH, CIE (Commission Internationale de l’Éclairage) L*a*b* color coordinates, ascorbic acids, procyanidin A1 and B2 concentrations, total anthocyanin content (TAC), total flavonoid content (TFC), total phenolic content (TPC), FRAP (ferric reducing antioxidant power) antioxidant capacity, and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity were measured. The ultrasonication treatments preserved TPC better than the thermo-sonication treatment, resulting in values of 12.85 ± 0.38 mg GAE/100 mL for the ultrasound-only treatment at 3 min (US-3), while progressively decreased TPC values were recorded for thermo-sonication. Enhanced FRAP values of 0.64 to 1.78 mmol at 7 min (TS35-7), were recorded for thermo-sonication at 35 °C, indicating reducing compounds bioaccessibility. Procyanidin A1 and B2 concentrations which ranged from 10.46 to 12.27 and 14.63–15.90 mg/100 mL, respectively, were statistically stable in all thermo-sonication treatment conditions (p > 0.05), an essential finding from the study, knowing the significance of A-type procyanidins in cranberry bioactivity. Decreased total anthocyanin content (TAC) was observed with all treatments, with the thermo-sonicated samples retaining more anthocyanin than ultrasound alone at 7 min (up to 130.70 mg CGE/L for TS-35 °C); similarly, TS-45 °C treated samples had the most redness a* value up to 17.56, while retaining pH stability across all the treatment conditions. These findings suggest that thermo-sonication treatment conditions significantly impact cranberry juice quality characteristics, with temperature and treatment duration equally governing the level of bioactive compound alteration.