Physicochemical, Bioactive, and Clinical Evaluation of Blueberry-Enriched Kombucha as a Functional Beverage

This study aimed to develop a blueberry-flavored kombucha and evaluate its functional properties and effects on human intestinal health. The beverage was produced from green tea and sucrose, fermented with a symbiotic culture of bacteria and yeasts (SCOBY), followed by the addition of blueberry syrup and a second fermentation stage. Active formulations (with viable microbiota) and sterilized control formulations were prepared. Physicochemical, microbiological, and bioactive analyses were performed, along with a controlled clinical trial involving 39 adults who consumed 100 mL of the beverage daily for 28 days. The active kombucha exhibited high microbial viability, with appropriate levels of yeasts, lactic acid bacteria, and acetic acid bacteria, as well as a low pH and safe alcohol content (0.20%). It also presented higher antioxidant activity (IC₅₀ = 10.66 µL/mL) and elevated levels of phenolic compounds, flavonoids, and anthocyanins compared to the control. Clinically, participants consuming the active kombucha were associated with improvements in intestinal function, including normalization of stool consistency (Bristol scale type 4) and reductions in self-reported abdominal symptoms such as bloating and pain. Approximately 90% of participants reported a perceived improvement in bowel function. The results suggest that blueberry kombucha is a promising functional beverage with favorable bioactive characteristics and the potential to support gastrointestinal health. However, these findings should be interpreted with caution due to the exploratory nature of the clinical evaluation and warrant confirmation in larger clinical studies involving clinically characterized populations. PRACTICAL APPLICATIONS: This research can be applied by the food industry to create a ready-to-drink kombucha enriched with blueberry, combining good taste with ingredients that have the potential to support digestive health. It offers consumers a natural beverage option with antioxidant compounds and live cultures that may help maintain regular intestinal function. This product could be positioned as a functional drink for everyday consumption as part of a balanced diet.