Improvement of cocoa powder properties through ultrasonic- and microwave-assisted alkalization

Improving the process efficiency is still a challenge in the alkalization process of cocoa powder. This research aims to study the effect of ultrasonic- and microwave-assisted alkalization on the quality attributes of cocoa powder. Three levels of process duration were used (5, 10, and 15 min), and then the physical and antioxidant properties of the cocoa powder were evaluated. The results show that ultrasonic- and microwave-assisted alkalization is more effective in improving cocoa powder's darkness and red intensity than the conventional alkalization process. The cocoa powder produced using ultrasonic- and microwave-assisted alkalization significantly improved the pH to 7.59, solubility from 20 to 28% and wetting time to almost twice, depending on the type and duration of the process. However, both advanced methods caused a significant decrease in total phenols, flavonoids, and antioxidant activity by about 35, 22, and 38%, respectively, compared to the conventional method. This research provides further information on the potential use of ultrasonication and microwave techniques, particularly in cocoa powder processing that has not been explored previously.