Chemical properties and sensory profile of kombucha prepared from different post-harvest processed arabica coffee

Abstract

Kombucha, a fermented beverage traditionally produced using a symbiotic culture of bacteria and yeast (SCOBY), has gained considerable attention as a functional drink due to its potential health benefits. The growing demand for kombucha variants has stimulated the exploration of coffee as a substrate, with processing methods potentially influencing the biochemical and sensory characteristics of the final product. This study evaluated the chemical and sensory characteristics of kombucha produced from coffee beans processed using three methods (natural, washed, and honey processing) obtained from farmers in Magelang, Indonesia. Chemical analyses included antioxidant activity (AA), determined using the DPPH radical-scavenging method; total phenolic content (TPC), determined using a colorimetric method; total titratable acidity (TTA), determined by acid-base titration; caffeine content (CC), determined gravimetrically; and total soluble solids (TSS), measured using a refractometer. The results indicated no significant differences among the three coffee processing methods for any of the chemical parameters (AA, 45-49%; TPC, 1.51-1.67 mg GAE/g; TTA, 0.45-0.54%; and CC, 0.29-0.49%), except for TSS (11.0-12.6°Brix), suggesting that SCOBY fermentation may have reduced differences in chemical composition regardless of the initial coffee processing method. Sensory evaluation was conducted using a hedonic test assessing aroma, taste, color, and overall acceptability, combined with the Check-All-That-Apply (CATA) method. The results revealed that kombucha produced from honey-processed coffee was associated with positive attributes such as citrus, floral, honey, and sparkling aromas, whereas the naturaland washed-processed variants were associated with woody, bitter, alcoholic, and refreshing attributes. Principal Coordinate Analysis of the CATA data indicated that consumer liking was positively correlated with refreshing, sparkling, and herbal descriptors. These findings suggest that, although the chemical profile did not differ significantly among the samples, the coffee processing method influenced the sensory profile of the resulting kombucha.