Enhancing juice yield and bioactive compounds in red dragon fruit juice through pulsed electric field and ultrasonic pre-treatments: process optimization and comparative evaluation

This study optimized pulsed electric field (PEF) and ultrasonic (US) pretreatments for enhancing juice extraction from red dragon fruit (Hylocereus polyrhizus). PEF parameters were varied using a Box-Behnken design, while US conditions were optimized using a 3-level factorial design. The impact of pretreatments on juice yield, betacyanin content, total phenolics, and antioxidant activity was evaluated. Optimal PEF conditions were 10 kV/cm, 20 μs pulse width, and 50 pulses (40 kJ/kg), while the best US treatment used 40 % amplitude (300 W output power) for 10 min. US pretreatment significantly improved juice yield (72.83 %), betacyanin content (10.08 %), total phenolic content (19.13 %), and DPPH radical scavenging activity (12.33 %) compared to untreated control juice. When directly comparing the two treatments, US pretreatment resulted in a 21.73 % higher juice yield, 6.67 % higher betacyanin content, 12.35 % higher TPC, and 3.08 % higher DPPH activity than PEF treatment, indicating its superior effectiveness in enhancing both quality and nutritional attributes of the juice. SEM analysis confirmed structural modifications, indicating enhanced cell disruption. The study demonstrates that US pretreatment is more effective than PEF in improving juice yield and bioactive retention, offering a promising non-thermal approach for juice processing industries.