Alkalisasi Menggunakan Microwave dengan Variasi Konsentrasi Na2CO3 pada Bubuk Kakao Fermentasi dan Non-fermentasi

Abstract

Indonesia is one of the world’s largest cocoa producers, which opens up opportunities for the development of downstream products such as cocoa powder. Cocoa powder is categorized into fermented types with high acidity (pH around 5) and non-fermented types with a dominant bitter taste (pH around 6.6) and higher polyphenol content. Alkalization is used to improve the physical and sensory characteristics of cocoa powder; however, conventional methods are timeconsuming, so this study employs microwave technology. The study aims to determine the characteristics of fermented and non-fermented cocoa powder produced through microwave alkalization using varying concentrations of sodium carbonate (Na₂CO₃). A two-factor completely randomized design was used, varying Na₂CO₃ concentration (1.5%; 2%; and 2.5% w/v) and cocoa powder type (fermented and non-fermented). Alkalization was performed using a microwave for 12 minutes, followed by drying at 65°C for 16 hours, grinding, and sieving through an 80-mesh screen. Physical and chemical parameters were statistically analyzed using two-way ANOVA; where significant, they were further tested using Duncan’s Multiple Range Test, while hedonic evaluation was analyzed using the chi-square test. The results showed that variations in Na₂CO₃ concentration and cocoa powder type had a significant effect on all physical and chemical parameters tested. Increased alkali concentration reduced lightness (L*), accelerated wetting time among the alkalized samples, increased solubility, reduced the sedimentation index, increased pH (from 5.43–5.76 to 8.28–9.85), and reduced total polyphenols. Fermented powder yielded higher solubility and polyphenol content, while nonfermented powder exhibited stable wetting time and sedimentation index, due to differences in cell structure and chemical composition resulting from the processing methods of each powder type. Hedonic test results showed that alkali concentration and powder type had a significant effect on the likability of color, taste, and overall impression, but did not significantly affect aroma likability. Increasing the alkali concentration from 2% to 2.5% tended to produce an alkaline taste that masked the characteristic flavor of chocolate, thereby reducing the panelists’ acceptance levels. In conclusion, the concentration of Na₂CO₃ and the type of cocoa powder significantly influence the physical, chemical, and sensory characteristics of cocoa powder produced by microwave alkalization.