Effect of purple sweet potato enzymatic hydrolysate on the physicochemical properties and sensory quality of kombucha beverages

Abstract

Kombucha is a beverage traditionally made from sweetened black tea fermented by the Symbiotic Colony of Bacteria and Yeasts (SCOBY). This study incorporated purple sweet potato enzymatic hydrolysate (PSPEH) into black tea kombucha as a partial sucrose substitute to evaluate its effects on fermentation characteristics and product quality. PSPEH supplementation promoted acid production, increased total acidity and acetic acid levels, and reduced the final pH to 2.8-3.0. Total phenolic content increased progressively with supplementation level, peaking at 338.4 mg GAE/L, concomitant with significantly enhanced DPPH and ABTS + scavenging capacities. Volatile flavor profiling revealed substantial flavor restructuring. Total esters surged approximately 5.5-fold (to 5.45%), terpene alcohols including linalool and α-terpineol accumulated markedly, whereas total aldehydes declined by 29.8%. Chromatic analysis confirmed a dramatic red-purple shift (ΔE*>45) attributable to acylated anthocyanins. Sensory evaluation identified the KB40 formulation as optimal, achieving the highest overall acceptability score (8.8/10). PSPEH improved the antioxidant capacity, flavor, color, and sensory properties of kombucha. This approach offers a viable route to anthocyanin-enriched fermented beverages.