A colorimetric mixed pH dye-based indicator with potential for the development of intelligent packaging,
as a “chemical barcode” for real-time monitoring of intermediate-moisture dessert spoilage, is described.
This on-package indicator contains mixed pH-sensitive dyes, bromothymol blue and methyl red, that
respond through visible color change to carbon dioxide (CO2) as a spoilage metabolite. Both indicator solution
and indicator label characteristics were studied, as well as their response to CO2. A kinetic approach
was used to correlate the response of the indicator label to the changes in intermediate-moisture dessert
spoilage. Color changes, in terms of total color difference of a mixed pH dye-based indicator, correlated
well with CO2 levels of intermediate-moisture dessert. Trials on golden drop have verified that the indicator
response correlates with microbial growth patterns in dessert samples, thus enabling the real-time
monitoring of spoilage either at various constant temperatures or with temperature fluctuation.