Physicochemical Property Analyses of Deep-Frozen Kimchi Cabbage during Long-Term Storage

Temperature control is critical to prevent overfermentation during the storage, distribution, and export of kimchi. Studies to optimize the freezing conditions for kimchi are lacking. Thus, the present study aimed to evaluate the optimum freezing and storage temperature for kimchi during long-term storage. Kimchi was frozen at −18°C, −40°C, and −80°C for 4 months, followed by thawing at 2°C until the core temperature reached 0°C. Thawing loss was maximum for samples frozen at −18°C, with increased cell membrane disruption, thus considerably decreasing the hardness. Compared to kimchi stored at −18°C, those frozen at −40°C and −80°C resisted the changes in pH, titratable acidity, reducing sugar content, antioxidant activity, and total phenol content. However, the total aerobic count and total lactic acid bacteria values of samples frozen at −18°C sharply decreased among treatments. Therefore, freezing at freezer temperature, particularly −80°C is ideal to maintain the kimchi quality for long-term storage.