Response Surface Methodology for Optimizing Fermentation Conditions in Determining The Antioxidant Activity of Parijoto (Medinella speciosa Blume) Fruit-Based Kombucha

Parijoto fruit (Medinilla speciose Blume) kombucha has been made by fermenting a brew of parijoto fruit tea using a symbiotic culture of bacteria and yeast (SCOBY). Optimizing these fermentation conditions had been taken with the fermentation time, sucrose concentration and SCOBY concentration as treatments. This research aims to identify the optimal outcomes for antioxidant activity by employing the response surface methodology through the Box-Behnken design (design expert 10), with 3 factors, namely factor A (fermentation time: 3, 6, 9, 12, 15 days), factor B (sucrose concentration: 5, 10, 15, 20, 25%) and factor C (SCOBY concentration 4, 5, 6, 7, 8%). The results indicaed that the optimal fermentation conditions for parijoto fruit-based kombucha were a fermentation time of 12.65 days, a sucrose concentration of 20.70%, and a SCOBY concentration of 7.52% which resulted in total phenolics of 10.31 mg GAE/mL, flavanoids 7.17mg CE/ mL and antioxidant activity (RSA-DPPH) 82.33%. The quadratic equation model that describes the antioxidant activity of parijoto fruit kombucha is Antioxidant activity = 82.87 – 0.01A + 0.19B + 0.462 + 0.01AC + 0.01BC – 1.99A2 – 1.99B2 - 2.44C2. In conclusion, optimization of parijoto fruit kombucha fermentation conditions can be determined based on time, sucrose concentration and SCOBY concentration using response surface methodology-box behnken design.