Among all time–temperature integrator (TTI) types, microbial-based TTIs prevail since their response is
directly related to food spoilage. For the development of lactic acid bacteria-based TTIs, optimum pHindicators
were chosen as follows. Five kinds of potential pH-indicators and four species of lactic acid
bacteria were used to create microbial-based TTIs. The qualifying standards for pH-indicator selection
were defined as (1) the effect of microorganism inhibition, (2) the simplicity of mechanistic interpretation
of the color development reaction, and (3) intensity of color development. In particular, the reaction
of TTI color development could be enhanced from non zero-order to zero-order. Overall, the optimum
pH-indicator for the microbial TTIs was bromocresol green, followed by bromocresol purple, bromophenol
blue, chlorophenol red, and congo red, in descending rank order. In conclusion, the choice of pH-indicators
was found to be selective to assure effective color development of TTI.