Nashi Pear (Pyrus pyrifolia) Pomace as a Source of Sucrose and Functional Ingredients for Kombucha Fermentation

Kombucha, a fermented tea beverage celebrated for its unique flavor and health-promoting properties, is traditionally produced from sugared tea and a symbiotic culture of bacteria and yeast (SCOBY). In this study, Nashi pear (Pyrus pyrifolia) pomace, a nutrient-rich by-product of juice processing, was explored as a novel substrate for kombucha production, combining sustainability with functional innovation. Beverages were prepared using black tea or pear pomace with varying sugar concentrations (3%, 5%, 7% w/v) and fermented for six days at 22 °C. Physicochemical parameters, bioactive compounds, antioxidant activity, color, and microbial populations were systematically analyzed. Pomace-based kombucha exhibited higher initial pH (4.3–4.7) and higher initial titratable acidity compared to tea-based variants (pH 3.4–3.6). These values stabilized at 3.6–3.8 by the end of fermentation, ensuring safety while preserving bioactive stability. While tea kombucha had higher polyphenol content (943.81–967.74 mg GAE/100 mL) and antioxidant activity (52.22–99.87% DPPH scavenging), pear pomace kombucha offered moderate bioactivity (up to 435.13 mg GAE/100 mL and 33.52% DPPH scavenging) and distinctive color (significantly higher b* value reaching 42.7), along with robust microbial growth. The results demonstrate that Nashi pear pomace can serve as a functional, eco-friendly alternative substrate, transforming fruit processing waste into a value-added beverage with enhanced health-promoting properties. This approach highlights a sustainable pathway for circular economy practices in food production and introduces a promising direction for innovative kombucha formulations.