Detection of fish spoilage during the storage using a simple colorimetric paper sensor

In this study, a simple and sensitive colorimetric sensor towards pH changes for the detection of fish spoilage during storage at room and refrigeration temperature is presented. Colorimetric sensor was developed using Whatman filter paper No. 1 and water soluble anthocyanin pigments extracted from red cabbage. Fish spoilage was monitored based on anthocyanin color change in various pH. Microbial growth during storage and production of proteolytic enzymes resulted in protein degradation, accumulation of volatile amine compounds, increase in the pH and finally color change of anthocyanin-impregnated filter paper. Color change was measured using the CIELab method. The colorimetric sensor was validated by measuring total volatile basic nitrogen (TVB-N) levels, peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and microbial populations in fish samples. Results indicated that the values of TVBN, pH, PV and TBARS increased with time of storage which was evidence of fish spoilage development. Also, the results were in accordance with color change of colorimetric sensor during storage and showed that proposed system enjoys a high sensitivity to pH variations. Therefore, the simple colorimetric sensor is capable to use in intelligent packaging.