Colorimetric Paper-Based Dual Indicator Label for Real-Time Monitoring of Fish Freshness.

Area of Science:

• Food Science
• Analytical Chemistry
• Materials Science

Background:

• Monitoring fish freshness is crucial for consumers, retailers, and the fishing industry.
• Developing simple, fast, non-destructive, and inexpensive real-time fish freshness monitoring methods is highly valuable.
• Intelligent or smart packaging offers a promising alternative for monitoring packaged fish conditions.

Purpose of the Study:

• To develop a novel on-package dual indicator label for real-time monitoring of milkfish (Chanos chanos) freshness.
• To create a simple, low-cost, and visually readable sensor for detecting fish spoilage.
• To correlate visual color changes with key fish freshness parameters.

Main Methods:

• Prepared paper-based pH sensors by dip-coating filter paper with bromocresol purple (BCP) and bromothymol blue (BTB).
• Immobilized BCP and BTB onto filter paper to create a dual indicator label.
• Visually monitored color changes of the label in response to milkfish degradation under room temperature and chiller conditions.

Main Results:

• The dual indicator label visually signaled milkfish freshness, with BCP changing from yellow to purple and BTB from orange to green-blue.
• Color changes correlated with pH shifts due to fish degradation, as well as changes in total volatile basic nitrogen (TVBN), total viable count (TVC), texture, and odor.
• Spoilage thresholds were identified at 8 hours under room temperature and 7 days under chiller conditions, indicated by distinct color changes.

Conclusions:

• The developed dual indicator label is a simple, low-cost, and effective on-package solution for real-time fish freshness monitoring.
• The colorimetric pH sensor provides an easy and accurate method for detecting fish spoilage visually.
• This technology can enhance food safety and quality assurance for milkfish and potentially other seafood products.