Effects of temperature fluctuations and phase transitions on quality attributes of frozen Korean white kimchi.

With global demand for kimchi rising, effective preservation methods that maintain quality and extend shelf life are increasingly important. This study evaluated the effects of temperature fluctuations and phase transitions on the microstructure and physicochemical properties of Korean white kimchi during 4 weeks of frozen storage under four conditions: glassy state at -45 °C without fluctuations, and glassy, rubbery, and partially thawed states with fluctuations. Although pH, titratable acidity, and reducing sugars remained stable, ice crystal formation, microstructure, drip loss, hardness, colour, and antioxidant activity were significantly affected. Principal component analysis revealed that storage time and phase transitions influenced the distribution of quality variables, resulting in clearer sample separation. Phase transition conditions thus affected quality changes during frozen storage. Storage in the glassy state without fluctuations suppressed large ice crystal formation and preserved structure and function. These findings support glassy-state storage as a practical strategy for long-term kimchi preservation.