Antioxidant Activity of the Combination of Morinda citrifolia and Alpinia galanga in Juice and Instant Beverage Powder Using the ABTS Method

A combination of Morinda citrifolia and Alpinia galanga is available as a traditional herbal product in two dosage forms, namely juice and instant beverage powder, known as kudu-laos jamu, which potentially exhibits an antioxidant effect. The research novelty of this study lies in the comparison of the antioxidant activity between two dosage forms using the ABTS method. Six formulations were evaluated, including single-plant and combined formulations in both juice (F1–F3) and powder (F4–F6) forms. The antioxidant activity was determined quantitatively by the IC₅₀ value. The results showed that all formulations exhibited antioxidant activity; however, their IC₅₀ values were higher than that of ascorbic acid (< 50 µg/mL), indicating very weak activity (> 200 µg/mL). Statistical analysis showed a significant difference between dosage forms; the IC₅₀ value in instant beverage powder formulations was higher compared with juice formulations. This condition is attributed to dilution by sucrose as the matrix in the powder formulations and to the thermal degradation of bioactive compounds during the processing stage. Therefore, further formulation optimization is required to preserve antioxidant potential in future studies.