Enhancing kombucha composition: Effects of sugarcane juice and cocoa honey on antioxidant properties, physicochemical, and chemical profile

Abstract This study aimed to evaluate the effect of different fermentation substrates on the physicochemical, chemical, and antioxidant characteristics of kombucha (T1: sugarcane juice at 15 ºBrix and cocoa honey; T2: sugarcane juice at 5 ºBrix and cocoa honey; T3: sucrose and cocoa honey; T4: sucrose control). The analyses included pH, soluble solids, titratable acidity, color, phenolic content, antioxidant activity, organic acids, ethanol, and volatile compounds, assessed during fermentation (0, 168, and 240 h). Reductions in soluble solids and pH were observed during fermentation. T1 showed higher production of acetic acid (7.99 g/L) and lactic acid (4.99 g/L) in 240 h. T1 and T2 showed higher alcohol content (1.99% and 1.08% ABV, respectively), classifying them as alcoholic kombuchas, whereas T3 and T4 remained non-alcoholic (< 0.5% ABV). T3 and T4 showed greater antioxidant stability, with T4 showing a higher concentration of total phenolics (913.26 mg GAE/100 mL) and T3 showing a greater ABTS+ radical scavenging (94.91%) in 240 h, while T1 exhibited a decline in free radical scavenging. 91 volatile compounds were identified. Acetic acid 2-phenylethyl ester was abundant in T2 and T4, while ethyl decanoate was abundant in T1 and T3 in 240 h. Sugarcane juice promoted efficient fermentation, thereby increasing organic acid production, while sucrose-based kombuchas showed greater antioxidant stability. T1 increased the levels of organic acids and volatiles, whereas T3 enhanced antioxidant activity with low alcohol. T3 and T4 are non-alcoholic beverages with high antioxidant potential, whereas T1 and T2 are alcoholic kombuchas that reach different market niches.