Fraud-proof methylcellulose-based fish freshness indicator: Reversibility in halochromic sensing of basic volatiles...

Area of Science:

• Food Science
• Materials Science
• Analytical Chemistry

Background:

• Animal-source foods, like fish, are common sources of foodborne illnesses.
• Intelligent packaging offers real-time monitoring of food freshness to prevent contamination.
• Colorimetric sensors utilizing natural compounds can indicate fish spoilage by detecting volatile compounds.

Purpose of the Study:

• To investigate the effect of ionic strength (IS) on colorimetric sensors for Lambari fish freshness.
• To optimize the chromatic response of anthocyanin-methylcellulose sensors using CaCl2.
• To develop a reliable method for real-time fish freshness assessment.

Main Methods:

• Incorporation of açai anthocyanin extracts into methylcellulose (MC) hydrocolloid matrices.
• Modulation of sensor color response by varying ionic strength (IS) with salts like CaCl2.
• Exposure of sensors to ammonia (NH3) and/or total volatile basic nitrogen (TVB-N) to simulate fish spoilage.
• Chromatic analysis and Principal Component Analysis (PCA) for sensor validation.

Main Results:

• Increasing IS enhanced the sensor's color sensitivity to NH3 and TVB-N, improving detection time.
• Specific ionic strengths and salts (LiCl, CaCl2, MgCl2) induced distinct, irreversible color changes (gray-green, blue, moss-green).
• The sensor accurately classified Lambari fish freshness according to Brazilian and European standards, maintaining functionality for 60 days.

Conclusions:

• Ionic strength is a critical factor in controlling the chromatic properties of anthocyanin-based colorimetric sensors.
• The developed sensor offers a promising, cost-effective method for monitoring fish quality, safety, and shelf-life.
• This research highlights the potential of natural compounds in intelligent food packaging solutions.