Polyaniline-Based Smart Films as Colorimetric Indicators for Food Spoilage Detection

Abstract

Food safety remains a global concern, and the development of low-cost, real-time freshness indicators has attracted growing attention. In this study, polyaniline (PANI)-based films were synthesized and evaluated as colorimetric sensors for monitoring the freshness of perishable food products. The films were prepared via in-situ oxidative polymerization and doped with camphorsulfonic acid to enhance sensitivity. UV–Vis spectroscopy and scanning electron microscopy confirmed the successful formation of uniform, conductive films with porous morphologies. The colorimetric response was assessed by exposing films to volatile amines released during fish and meat spoilage. Results demonstrated a clear color transition from dark green to blue with increasing ammonia concentration, providing a simple visual indicator of spoilage. Response times were rapid, with color changes observable within 5–10 minutes of exposure to spoiled food vapors. Reversibility tests showed partial recovery under vacuum conditions, indicating reusability. The films exhibited strong stability over storage periods of up to six months, without significant loss of sensitivity. These findings suggest that PANI-based smart films could serve as practical freshness indicators for intelligent packaging applications, offering consumers an immediate and reliable means of assessing food quality.