Changes in Total Phenolic Concentration and Antioxidant Capacity of Fermented Guava (Psidium guajava) Juice Extract by SCOBY

The physiological effect of the bioactive compound as a natural antioxidant can inhibit the pathogenesis of various diseases involving oxidative reactions. Increase public awareness of healthy living, encourage greater demand for healthy foods that provide health advantages to the body. As a useful beverage, guava juice extract (Psidium guajava) fermented by SCOBY as a candidate source of potential in enhancing body immunity. The goal of this research was to assess changes in total polyphenol concentration and free radical inhibitors based on the duration of fermentation of guava juice extract fermented by SCOBY. The research design of fermented guava extract formulation using Completely Randomized Design (CRD), with the treatment being studied was a variation of fermentation time 0 to 12 days, with SCOBY culture at 10% w/v and sucrose 10% w/v as carbon sources. According to the results, differing fermentation periods had a substantial effect on total phenolic concentration. (TPC) and free radical inhibitory activity, as well as other characteristics. The longer the fermentation can increase the total phenolic concentration, total acid, free radical inhibitory activity, and reduce flavonoids and pH. The optimum conditions were obtained based on the 2.2-Diphenyl-1-picrylhydrazyl radical scavenging (DPPH) assay, the inhibition of 2(2-Azino-bis(3 ethylbenzothiazoline-6-sulfonic acid (ABTS) activity and the greatest overall phenolic concentration (TPC) was obtained at 10 days fermentation with DPPH scavenging activity 94.49%, highest ABTS scavenging activity 55.25%, TPC of 1,35 mg GAE/mL, Total flavonoid 254 ppm.