Effects of Ultraviolet Processing on the Quality, Microbial Inactivation, and Shelf Life of Licorice Drink

Abstract

Licorice drink is a phenolic-rich traditional beverage with high sensory appeal but limited shelf life due to microbial spoilage. This study evaluated ultraviolet-C (UV-C) processing as a non-thermal preservation method using a continuous-flow system (0.022-1.192 J/cm & sup2;) with varying lamp numbers, treatment cycles, and temperatures based on a Box-Behnken design. The physicochemical properties, color, bioactive compounds, microbial load, sensory attributes, and storage stability were assessed. UV-C significantly reduced the indigenous microflora, achieving undetectable bacterial levels under high-dose conditions while largely preserving quality. Response surface methodology identified optimal conditions (29 degrees C, two cycles, four lamps) that balanced microbial reduction and quality retention. The shelf life was extended to 40 days at 4 degrees C and 30 days at 22 degrees C. UV-C shows strong potential for improving the microbial stability of plant-based beverages, although the results indicate microbial load reduction rather than validated microbial safety.