Design of colorimetric indicator based on curcumin for detection of trout spoilage

In this study, natural dye curcumin wasused to monitor the quality of packaged fish meat through color changing indicators and the color changes of the indicators were evaluated visually and with colorimeter during storage of fish samples at room temperature (for 60 hours) and in the refrigerator (for 12 days). In order to evaluate performance of paper indicators for monitoring the quality of fish, the quality characteristics of fish such as total viable count, pH, and TVB-N were evaluated. This indicator had very good characteristics such as less moisture absorption than the control, excellent stability during storage for 30 days, and high selectivity to pH changes. The FTIR results showed that the curcumin was well stabilized on cellulose filter paper. The results of color changes of the indicator during fish storage indicated that with increasing the storage time, the brightness (L *) of the indicator based on curcumin significantly decreased and red-green (a *) and yellow - Blue (b *) parameters increased. Colorimetric indicator based on curcumin indicated significant color changes from yellow to orange due to sensitivity to pH and detection of TVB-N and hydrogen sulfide compounds. According to the results obtained from the qualitative characteristics of fish in relation to performance and function of colorimetric indicator during fish spoilage, it can be concluded that curcumin provides a promising approach in intelligent packaging systems for meat products to monitor fish meat freshness.