A feasibility study of application of laccase-based time-temperature indicator to kimchi quality control on fermentation process

Kimchi, in factories or during transportation, is usually stacked on shelves at different heights, which affects temperature and thus kimchi quality. In this study, a time-temperature indicator (TTI) was used to control such quality variations. A case study was conducted to evaluate the validity of using the TTI; one group of small packages of young kimchi had the TTI attached whereas the other group did not. They were stored on shelves of different heights (i.e., top, middle, and bottom) in a laboratory fermentor. The samples with TTIs were individually fermented until the color of the TTIs reached a threshold level, whereas the samples without TTIs were collectively fermented for a predetermined time at a given temperature. The qualities of fermented samples including pH, acidity, microbial counts, and reducing sugars were analyzed. The samples with TTIs had more uniform qualities that were closer to the targets than those without TTIs. These results suggest that TTIs are practical tools to control kimchi quality in terms of temperature variation.