Effects of combined treatment with ultraviolet-C irradiation and grape seed extract followed by supercooled storage on microbial inactivation and quality of dongchimi

- UV-C and GSE reduced initial total aerobic bacteria, LAB, and fungi in dongchimi.
- Dongchimi juice was supercooled to −3 °C without ice crystal formation.
- Dongchimi shelf life was extended by UV-C, GSE, and supercooled storage.

Dongchimi is a watery variety of kimchi prepared using firm radish and condiments. Over-ripening is the most undesirable outcome of dongchimi fermentation, resulting in softening of texture and an undesirable taste. Herein, the effects of combined treatment with ultraviolet-C (UV-C) irradiation and grape seed extract (GSE) supplementation, followed by supercooled storage, on the quality of dongchimi were investigated. Microbial inactivation tests showed that 6 kJ/m2 UV-C irradiation and 0.1% GSE supplementation before storage significantly reduced the populations of total aerobic bacteria, fungi, and lactic acid bacteria in dongchimi. Supercooled storage (−3 °C) delayed microbial growth in dongchimi compared to refrigeration (4 °C and 10 °C). Supercooled storage also suppressed changes in pH and titratable acidity in dongchimi. The hardness and colour of the radish slices did not vary with the treatments. Sensory evaluation results indicated that the qualities of dongchimi treated with the combination of UV-C and GSE followed by storage at −3 °C were better than those with other treatments. Thus, UV-C irradiation and GSE supplementation improved the final quality and extended dongchimi shelf life under supercooled storage at −3 °C without ice crystal nucleation and formation.