Monitoring Meat Freshness with Intelligent Colorimetric Labels Containing Red Cabbage Anthocyanins Copigmented with...

Area of Science:

• Food Science
• Materials Science
• Analytical Chemistry

Background:

• Developing reliable and stable pH-responsive color indicators is crucial for food freshness monitoring.
• Red cabbage anthocyanins (Anth) offer potential as natural pH indicators but often lack stability.
• Polyvinyl alcohol (PVA) provides a versatile matrix for developing functional indicator systems.

Purpose of the Study:

• To develop a stable, pH-responsive color indicator using red cabbage anthocyanin (Anth) copigmented with gelatin and gallic acid (GA) in a polyvinyl alcohol (PVA) matrix.
• To evaluate the indicator's performance in terms of color change, stability (light, humidity), and sensitivity to volatile basic amines.
• To assess the potential application of the developed indicator for monitoring raw beef freshness.

Main Methods:

• Synthesized a polyvinyl alcohol (PVA)-based indicator incorporating red cabbage anthocyanin (Anth), gelatin, and gallic acid (GA).
• Tested the indicator's color response across a pH range of 2-11 and its stability under 97% relative humidity at pH 2 and 7.
• Assessed sensitivity to volatile basic amines (dimethylamine, ammonia, trimethylamine) and evaluated its performance in detecting spoilage in raw beef.

Main Results:

• The GA/gelatin/Anth/PVA indicator demonstrated high light resistance and distinct color changes across pH 2-11.
• The indicator maintained stable color indication in solid systems (pH 2 and 7) at 97% relative humidity.
• GA/gelatin/Anth/PVA showed highest sensitivity to dimethylamine, followed by ammonia and trimethylamine, and signaled spoilage in beef (21.0 mg/100 g TVBN) with a purple to blue color change.

Conclusions:

• The GA/gelatin/Anth/PVA indicator exhibits excellent stability and pH responsiveness, making it suitable for various applications.
• The indicator's sensitivity to volatile basic amines and its ability to detect spoilage in raw beef highlight its potential as a food freshness sensor.
• The incorporation of gelatin and gallic acid enhances the indicator's properties, including thermal stability and water solubility.