Enhancement of Antioxidant Activity and Fermentation Kinetics of Kombucha using Graviola Cheong: A Comparative Study

Aims: This study focused on the fermentation of kombucha using graviola (Annona muricata) fruit infusion/Cheong and aimed to develop a layered fermentation approach for kombucha production through secondary fermentation using an ancient Korean fermentation syrup known as Cheong, with comparative evaluation of its antioxidant properties and bioactivity against standard kombucha. Study Design: This study employed an experimental design to evaluate the effects of incorporating graviola (Annona muricata) Cheong during secondary fermentation. Primary fermentation was carried out using a symbiotic culture of bacteria and yeast in tea infusions containing sugar for 7 days. Comparative studies were performed between standard kombucha and graviola Cheong-infused kombucha, which were subjected to quantitative and qualitative analyses, including pH, specific gravity, Brix, titratable acidity, total phenolic content, antioxidant properties, microbial analysis, and sensory evaluation of the layered kombucha. Place and Duration of Study: Department of Food, Padmashree Institute of Management and Sciences, between January 2025 and February 2026. Methodology: Primary fermentation was carried out using a symbiotic culture of bacteria and yeast for 7 days at room temperature. On Day 7, graviola (Annona muricata) Cheong, prepared using a 50:50 ratio of graviola concentrate and sugar, was incorporated, followed by secondary fermentation for an additional 7 days, resulting in a total fermentation period of 14 days. Results: The layered fermentation demonstrated significant improvements in antioxidant activity and enhanced sensory complexity compared with standard kombucha formulations. The incorporation of Cheong was associated with increased bioactive compound retention and the development of a unique flavour profile while maintaining a long shelf life and microbial stability of the fermented product. Conclusion: This study demonstrates the potential of layered fermentation as an innovative approach for developing value-added kombucha beverages with improved functional properties and potential commercial applications in the fermented beverage industry.