Comparative evaluation of pulsed electric field and assisted technology alkalization on the quality characteristics of cocoa powder

This study investigates the use of thermal (T), pulsed electric field (PEF), combined PEF & T (PEF + T) and combined PEF and ultrasound (US) treatments (PEF + US) as alternatives to conventional thermal alkalization of cocoa powder. The study aimed to evaluate the effects of T, PEF, PEF + T, and PEF + US on the physicochemical, functional, and antioxidant characteristics of cocoa powder at different PEF voltages (10–40 kV/cm) and in combination with fixed US conditions (40 kHz, 10 min). The alkalization of cocoa powder was performed using a 0.5 % potassium carbonate solution, followed by various treatment combinations. Among these, samples subjected to PEF treatment at 10 kV/cm demonstrated superior retention of total phenolic content (TPC) (32.54 mg GAE/g) and total flavonoid content (TFC) (2.79 mg QE/g) compared to other techniques, but exhibited poor solubility. The PEF 40 kV/cm + US treatment enhanced the retention of bioactive components (97.9 % theobromine and 81.09 % caffeine), a significantly higher concentration compared to other treatments. It also resulted in the highest solubility of 26.9 %, nearly 10 % greater than that of thermal alkalization. This improvement can be attributed to the elevated free amino acid content (3.5 mg/g) observed in the PEF 40 kV/cm + US treatment, as these low-molecular-weight, hydrophilic compounds facilitate solubility enhancement. Overall, PEF 40 kV/cm + US treatments emerged as a promising non-thermal alternative to conventional thermal alkalization, effectively improving the functional properties and retaining the bioactive components of cocoa powder.