Effects of UV-C in a Teflon-Coil and High Hydrostatic Pressure Combined Treatment for Maintenance of the Characteristic Quality of Dongchimi (Watery Radish Kimchi) during Room Temperature Storage

The effect of nonthermal ultraviolet-C light in a Teflon-coil (UV-C, fixed at 2.5 J/mL) and subsequent high hydrostatic pressure (HHP at 400–500 MPa at 25C for 1 min) combined treatment was evaluated in dongchimi juice during 5-day storage at room temperature. A helically wound Teflon-coil reactor was used for UV-C radiation to create a secondary eddy flow. Results showed that lactic acid bacteria (LAB) in dongchimi juice were more resistant to UV-C and HHP alone treatments. On the other hand, UV-HHP combined treatment resulted in greater reduction of LAB viable counts and also inhibited bacterial growth during room temperature storage and maintained the chemical quality of dongchimi juice via synergistic effect. Sensory analysis showed that nonthermal treatments effectively maintained the taste and flavor of dongchimi juice during room temperature storage than untreated and heat pasteurized samples. In conclusion, UV-HHP combined treatment offers an opportunity for marketing of dongchimi juice product at room temperature with characteristic quality. Practical Applications: Over-ripening of dongchimi (Korean watery radish kimchi) resulting from spontaneous LAB fermentation leads to development of an undesirable taste in the final product, and restricts marketing. This study attempted to overcome the issues of over-ripening in dongchimi juice by controlling LAB fermentation during storage using a combined application of nonthermal treatments such as UV-C light in a Teflon-coil and HHP via synergistic effect, without affecting characteristics of quality and freshness of this product. Available data from this study will benefit the food processing industry to introduce dongchimi juice product of characteristic quality with an extended palatable shelf life at room temperature.