Effects of sugar concentration, storage temperature on biologically active and physicochemical properties of kombucha from Perilla frutescens

Kombucha from Perilla frutescens is a novel fermented beverage rich in bioactive compounds. This study investigated the effects of sucrose concentration (0–20% w/v) on fermentation kinetics and the impact of storage temperature (4–6°C and 28–30°C) on bioactive retention, physicochemical properties, and microbiological stability over 28 days. Optimal fermentation was achieved at 10% sucrose, yielding the highest organic acid production (acetic acid 8.00 g/L, lactic acid 12.00 g/L) and stable antioxidant capacity (DPPH 2.41 mg AAE/mL). During storage, refrigeration at 4–6°C markedly improved retention of thermolabile compounds compared to 28–30°C: total anthocyanin content retained 5–6% higher, total polyphenols decreased only 22.9%, and DPPH radical-scavenging activity declined 24.4% (29.1% at 28–30°C). pH dropped by 12.3% under refrigeration (final 3.19). Microbial growth was strongly suppressed at 4–6°C (300-fold increase in TAMC) compared to 5,700-fold at 28–30°C. These findings demonstrate that 10% sucrose combined with cold storage (4–6°C) optimally preserves bioactive compounds, physicochemical stability, and microbiological safety, providing a scientific basis for commercial production of functional perilla kombucha.