Optimized Continuous Thermosonication for Sustainable Pasteurization of Orange and Dried Black Lime Juices:...

In pursuit of sustainable and efficient food processing solutions, a batch thermosonication system was successfully upgraded into a continuous thermosonication system (CTS) to improve pasteurization performance for orange juice (OJ) and dried black lime juice (DBLJ). The newly developed CTS integrates five core components: thermal heating, pumping, heat exchange, pasteurization, and electrical control units. Using response surface methodology, the effects of power (1.676-1.764 kW), mass flow rate (0.0142-0.0016 kg/s), and processing temperature (30°C-50°C) on the techno-functional, physicochemical, and microbiological attributes of the juices were optimized. At optimal conditions, the CTS reduced specific energy consumption by 29.71% in OJ and 30.51% in DBLJ, relative to traditional pasteurization (TP: 90°C for 60 s), while improving energy efficiency and process productivity. No significant differences (p > 0.05) were observed in pH, titratable acidity, or sensory characteristics compared to untreated fresh juice. Moreover, the residual activity of pectin methylesterase was effectively reduced to 7.48% ± 0.11% (OJ) and 6.42% ± 0.074% (DBLJ). Microbiological analysis revealed complete inactivation of total bacterial count, psychrotrophic bacteria, coliforms, and yeasts and molds. Additionally, RP-HPLC analysis confirmed enhancement in the bioactive compound content in CTS-treated juices compared to both fresh and TP samples. These findings demonstrate that the CTS approach offers a sustainable, energy-efficient, and quality-preserving alternative for juice pasteurization, highlighting its potential application in modern food processing industries.