The main purpose for application of the color indicators to kimchi packaging is to evaluate easily and reliably the degree of fermentation of commercially packaged kimchi products in a non-destructive way during distribution and retail sale. The TA values of kimchi were hence compared with the TCD values of the indicators as illustrated in Fig. 6.
TCD of each indicator closely correlated with TA, as little influenced by temperature. The TA values give a nearly straight line against the TCD values of the BP type indicator,whereas they formed a concave curve over those of the MR type. Correlation between the TCD of the indicators and the TA of kimchi was obviously proved by a regression analysis.
The determination coefficients (r2),determined by the least-squares method (P < 0:05), for TCD of the indicators with respect to TA of kimchi were 0.930 for the BP type and 0.804 for the MR type. Present result suggests that the BP type indicator can be used successfully as a full time-fermentation indicator for kimchi products.
However, the MR type may be applied only as a ripeness/unripeness indicator to packaged kimchi because its color change rate nearly reaches to zero at the TA values more than 0.7 mg/dl.
Kimchi when fermented at pH 4.2±4.4 and TA of 0.6±0.8 mg/dl is generally regarded as a well ripened state
In conclusion, the color changes of the developed indicators represented properly the degree of fermentation of kimchi. Such color indicators could be employed as an effective active packaging technology for evaluating the ripeness of kimchi products non-destructively.Further studies on such color indicators for packaged foods other than kimchi are needed in order to increase
their potential value.