Fish Freshness Indicator for Sensing Fish Quality during Storage

Area of Science:

• Food Science
• Analytical Chemistry
• Material Science

Background:

• Fish spoilage involves the generation of volatile base compounds (TVB-N), including ammonia.
• Accurate and rapid assessment of fish freshness is crucial for food safety and quality control.
• Current methods for assessing fish spoilage can be time-consuming or destructive.

Purpose of the Study:

• To develop a novel, colorimetric freshness indicator for fish products.
• To utilize ammonia detection for real-time monitoring of fish spoilage.
• To incorporate environmentally friendly and economically viable materials into the indicator design.

Main Methods:

• Optimization of indicator mixture using cresol red and bromocresol purple based on ammonia concentration.
• Application of eco-DEHCH and Breathron film for indicator fabrication.
• Storage experiments with Chub mackerel, Spanish mackerel, and Largehead hairtail at 4, 10, and 20 °C for seven days.
• Monitoring of pH, TVB-N, total bacterial count, and ammonia content at 24-hour intervals.
• Colorimetric analysis of the indicator using the chromatic parameter ∆E.

Main Results:

• The indicator mixture effectively changed color in response to ammonia concentration.
• The chromatic parameter ∆E significantly increased with extended storage periods.
• The indicator demonstrated a distinct color transition from yellow to black and then purple, correlating with fish spoilage levels.
• Ammonia levels and bacterial counts increased, while pH decreased during storage, consistent with spoilage progression.

Conclusions:

• The developed freshness indicator accurately reflects the spoilage status of fish products.
• The color change mechanism is linked to ammonia release during fish decomposition.
• This indicator provides a rapid, non-destructive method for assessing fish quality and ensuring food safety.